Dr Simon McDonald has purchased Camillo’s extensive files and map collection, including a comprehensive data set for Madagascar. E-MAIL LINK Mobile Phone: +61 423 921 780
Very little is known about the potential gold deposits in Madagascar, but the country’s estimated gold production is far from negligible. It runs to approximately 3-4 t/y and “could easily be doubled” (Mining Annual Review – 1995, p 149).
This is a large amount considering that all of it presently comes from “artisan” mining – or very small syndicates – and mining is largely alluvial. Estimates of Madagascar’s total gold production since it began late last century is a highly respectable 70 tonnes.
Madagascar’s primary gold deposits are thought to be of mesothermal “lode” quartz-hosted type, and they are hosted in Proterozoic or, more frequently, Archean terrains. Lode gold deposits of this type account for nearly 20% of world deposits, and are largely responsible for the vigorous gold development of Australia, Canada, Brazil and Ghana.
There is no evidence in Madagascar of sediment-hosted gold deposits, pebble-conglomerate deposits, gold-rich porphyry copper deposits or epithermal gold deposits. Although their presence cannot be excluded given the current level of knowledge, their occurrence seems unlikely.
Madagascar’s geological records are far more difficult to access than is usual with African countries. This is particularly galling as, until 30 years ago, Madagascar was one of the best geologically studied countries in Africa, with several thousand first-class records.
Unfortunately, virtually all these records are in French and it is very difficult to gain access to them (Ph.D theses, obscure records buried in the archives of poorly organised institutions, etc.). There is no evidence to suggest that this situation will change in the near future.
Like many other countries in Africa, Madagascar flirted for almost two decades with socialist-inspired, centrally planned economic policies and this ended only very recently with the demise of Soviet communism.
The country’s economy suffered grievously from these policies. A more sober political line was re-established in 1993 with a return to a form of liberal democracy.
French influence in all Francophone Africa, and Madagascar in particular, continued long after the country’s formal decolonisation in the early ’60s. Indeed, it has only been in recent years that France made clear that her interest in French-speaking Africa was decreasing. This process started even before the devaluation and floating of currencies in ex-French African countries (including the Malagasy Franc) in May 1994.
This long-overdue decision greatly boosted indigenous production, particularly agriculture, and discouraged imports, particularly from France, which were directed essentially to an African urban elite.
Until 1995, African politicians gave financial support to various French political parties. The courtesy was reciprocated by very flexible bilateral co-operation agreements, which involved Madagascar.
The three factors mentioned above – stagnant economies, renunciation of socialism, and a lessened French influence – have created new opportunities in Francophone Africa, particularly in mining. This point has not been lost on the international community in west Africa, and IMR suggests that this perception could be extended to Madagascar.
A significant gold producer now and in the past, Madagascar is about the size of Spain (or 41% of South Africa), and contains prime Archean-Proterozoic terrains beneath its surface. The country remains one of the best gold exploration targets in Africa.
However, French cultural heritage is well rooted in Madagascar, and perhaps rightly so. Most Frenchmen had a special affinity with and liking of Madagascar, a fully independent and functional country long before colonisation.
The grotesque “technicians” from North Korea that arrived in the ’70s were received with mild incredulity by a sophisticated Malagasy society. Although very poor, Madagascar never seriously knew the cultural soul-searching of, say, Zaire or Ethiopia. The country remains to this day a unique Malagasy (not African) state, with an overlay of French language, French background and French culture. Any bullying will be resented. Overseas investors should take warning.
The present report aims to consolidate all available “open file” information on gold in Madagascar. The information is presented in a modern and, wherever necessary, interpretative way, and it is directed to major investors. For easy consultation, part of the material has been presented in computer-generated databases that can easily be down-loaded in the reader’s computer system and edited or increased at will.
Several factors have radically affected Madagascar in the past few years. Among these have been:
– The collapse of Soviet-type economies in the period 1989-1992.
– South African renunciation of Apartheid politics, and its opening up to democracy and trade, particularly with southern African countries.
– Madagascar’s adoption, on August 19, 1992, of a new constitution with a bicameral legislature, a National Assembly elected by universal suffrage, and a president as constitutional Head of State elected for a term of five years. The first elected president, Professor A. Zafy, was inaugurated in 1993.
– The renunciation by France in May 1994 of its policy to keep the Malagasy currency artificially pegged to the French franc.
All these circumstances, coupled by a sustained gold price, has created a situation in which gold exploration in a newly democratic country of great geological potential – such as Madagascar – suddenly makes sense.
The present Database is intended to fill a void of relevant information about Madagascar. Its objective is to present in a modern way what is known about gold in Madagascar from open-file sources. Regrettably, some of these sources are no long available in Madagascar itself.
As the great majority of the potential mining investors are English speaking this is the language which has been chosen for the Database.
The report is based on modern compilation methods. We have sought to use French reporting customs in a way that Anglo-Saxon readers will understand. We liberally used computer techniques such a tabulations, cross-indexing etc to provide the reader with immediately accessible information; actually we feel that this has been the most valuable side of our work: to present in a state-of-the-art framework information that can only be laboriously gathered in dusty files in Europe or Antananarivo.
3. SCOPE OF THE DATABASE
No-one has seriously explored for gold in Madagascar for nearly 50 years. Although gold has been mined in the country for more than a century, comparatively little is known about its objective potential. For this reason, Madagascar’s gold resources fall – by western standards – into the “hypothetical” or “speculative” categories, not “proved” or “possible” reserves.
Gold exploration in Madagascar, particularly in the initial stage, would be quite risky, and the crucial early phase of collating all the existing data would be very time-consuming, particularly for non-French investors. But these are precisely the investors presently sought after by the Malagasy authorities, understandably keen to enlarge their base of trading partners.
Madagascar’s authorities are well aware of their island’s gold potential, which is presently the country’s largest mineral export – albeit still clandestine and poorly regulated. The authorities are keen to attract major gold explorers, within a legal and fair framework.
4. METHODS USED
The information on Madagascar’s gold potential is rather dispersed. The main sources of information for the present Database have been:
1) A computerised search on Madagascar’s geology and metallogeny, utilising any CD-ROM geological database available in 1995;
2) Previous reports by IMR staff who had worked in Madagascar;
3) A detailed field visit to Madagascar in 1995;
4) Verbal communication in Madagascar or France with personnel personally involved in gold exploration in Madagascar;
5) Rapid examination of some satellite images of the country;
6) Study of various geological maps of Madagascar. The six sheets at 1:500,000 (1971) and the three sheets at 1:1,000,000 (1964) have been particularly useful as most major gold occurrences are recorded;
7) Articles and papers from professional journals and publications, not only on Madagascar but on its geological neighbours, including Tanzania, Mozambique, India, Sri Lanka and Antarctica.
As the senior author of the present report spent two years in Madagascar in the 1970s, and has made numerous visits since that time, the material above has been supplemented with personal information and opinions.
In presenting the information care has been taken to distinguish factual information from IMR’s personal opinions and considerations. A clear distinction between “matter of fact” and “matter of opinion” has been maintained throughout the Database.
The name of 216 recorded Malagasy gold prospects is given in three different databases ordered by name, gold district and genetic type (Tables 5,6 and 7). The geographic position of at least 130 gold prospects and gold districts is given in illustrative sketches (sketches 7/2 through 7/12).
Madagascar’s old French geographical names have now been changed to Malagasy ones (Fort Dauphin = Tƒlanaro, etc.). This can be slightly confusing, particularly when old documents or maps are consulted. The new “Malagasy” spelling of localities has been maintained throughout the Database.
In addition, until very recently the geographic co-ordinates in Madagascar were given using the “Laborde” co-ordinates system (see sketch 5.2.1). “Laborde” co-ordinates can be converted through a conveniently programmed Geographical Information System in any other modern co-ordinate system.
As technical French (or French/Malagasy) terms used in gold mining are not generally given in normal English-French dictionaries, a brief glossary of these terms has been included in the Database (Table 8a-8b). Its purpose is to allow people with even a very rudimentary knowledge of French, or those using non-specialist interpreters, to be able to communicate on the subjects of this Database.
5. GEOGRAPHICAL AND SOCIAL FRAMEWORK
5.1 Physical and social geography – General
The Democratic Republic of Madagascar (Madagascar throughout this report) comprises the Island of Madagascar, the world’s fourth largest island, and several much smaller off-shore islands.
Madagascar lies about 400 km from the African mainland across the Mozambique channel. In reality Madagascar is not part of Africa proper but a micro-continent of its own, stranded between Africa and Southern Asia. This is apparent not only by its population but also by its unique fauna and flora.
Madagascar extends 1,600 km from north to south and it is about 500 km wide. It covers an area of 587,000 km2, or slightly more than France and Belgium combined. Geologically, Madagascar is composed essentially of crystalline rock, which forms the central highlands that rise abruptly from the wide plains of the west coast. Once again, Madagascar’s mineral provinces present several similarities with S.E. Asian ones, particularly India and Sri Lanka.
It has been said that large islands (U.K., Japan, Cuba, etc) have a tendency to have “different” behaviour. If that is true, Madagascar is no exception.
Madagascar was the only African country – with the dubious exception of Ethiopia – that was independent long before colonial times. By the end of last century Madagascar had developed a truly unified government, supported by a regular standing army, a crude but effective judicial system, education, public works, administration and the like. The stone palace of the last Madagascan queen (Ranavalona III) still proudly overlooks Antananarivo.
In a way, Madagascar was more Asian than a typical African country; a distinction that survives to this day. During the “scramble for Africa”, France, excluded from East Africa after the famous “Fashoda” incident in Sudan, thought Madagascar an attractive prize. Its strategic position in the Indian Ocean, its perceived richness in mineral resources (and particularly coal – then a vital commodity for any major fleet) played an important part in this decision.
Madagascar was invaded by France in 1895 and become a French colony one year after. The country was entirely subdued only 10 years later.
Colonisation followed a typical pattern: appropriation of land by French settlers and companies, the exploitation of the peasantry through forced labour (although this practice predates French arrival), the imposition of an import-export economy – essentially based on coffee and vanilla – with the construction of roads and railroads to serve it. Gold exploitation at the beginning of the French colonisation had a profound effect on what was up to then a near cashless society, based on subsistence farming and barter.
Autocratic and alien as any colonial regime invariably is, there were positive aspects of French rule on the island: hospitals were built, a very effective administration was put in place and a Malagasy elite was trained to French intellectual standards. It is also fair to say that the French colonial administration was better than those of Portugal, Germany or Italy on the other side of the Mozambique channels, and more enlightened than the Belgians in the Congo.
Many Frenchmen took a sincere liking to Madagascar and some never returned to France (among them H. Besairie, the father of Malagasy geology). Mixed marriages were common. France always referred to its overseas African colonies as “Territoires d’Afrique et du Madagascar”, stressing the individuality of the latter. A nice and appreciated touch.
Malagasy units fighted with distinction in World War I.
It was during World War II that Madagascan history took a bizarre, and little known, turn. After France was overrun by Germany in 1940, Hitler toyed with the idea of shipping the several million undesirable European Jews to Madagascar (Gilbert, 1989 p.323) – a blander sort of “final solution”. A strongly anti-Semitic Vichy government showed an immediate and keen interest in the project, but neither the French nor the Germans had adequate ships or enough control of the sea to implement this odd scheme.
Throughout World War II, Madagascar – the “pearl” of the French colonial empire – was staunchly pro-Axis and pro-Vichy.
After the fall of Singapore, a slightly paranoid British high command saw Madagascar as being the next stepping-stone of Japan’s expanding empire. On May 9, 1942, a British contingent landed in the port of Diego Suarez (now Antiranana) under heavy French fire. On May 31, Japanese midget submarines on a suicide mission sank a British merchant ship and damaged a battleship in Diego Garcia (Gilbert, 1989, p.330).
It took weeks for the British forces – with many casualties – to fight every inch of the way to reach Antananarivo and put Madagascar under the “Free France” of De Gaulle’s rule.
At the end of WW2 a strong pro-independence movement took root in Madagascar. Open hostilities erupted in 1947. But most of Madagascar’s topography is unsuitable for guerrilla warfare and, contrary to Vietnam or Algeria, Madagascar had no sympathetic bordering countries. The rising was quashed with much bloodshed – more than 80,000 Malagasy casualties.
In 1956 the French “loi cadre” instituted universal suffrage and transferred a significant share of executive power to the Malagasy, essentially to the c”tier-dominated Parti Social D‚mocrate (PSD).
But in was not until the 1960s that De Gaulle’s France bowed to the inevitable and restored Madagascar to full independence, although on terms very favourable to France.
Under the Malagasy Republic’s first president, the “c”tier” Philibert Tsiranana, the French were allowed to retain their hold over trade and financial institutions and keep their military bases on the island. Tsiranana also maintained a dialogue with South Africa and refused contacts with communist countries.
The increasingly unpopular Tsiranana was overthrown by a military coup in 1972 and this initiated a fundamental change in Malagasy policy. Aid agreements with France were renegotiated, the French military bases were closed down and so was an important NASA tracking station.
The economy saw a return to the collective work system that had been practised in the rural areas before colonisation. The new government also severed diplomatic relations with South Africa, Taiwan and Israel and formed new links with China, the USSR and especially with North Korea.
Several military men succeeded each other in rapid succession and eventually the government stabilised under Lt-Commdr. Didier Ratsiraka, a “c”tier”, in 1975. Banks were nationalised, and a network of public corporations was set up to deal with the agricultural, marketing and even mining sectors. The petroleum refinery and most mineral resources were nationalised. By and large the new leftish tendencies of the Government resulted in costly failures exacerbated by the 1981-82 international debt crisis.
By 1990 the Ratsiraka’s regime, like most left-leaning regimes worldwide, was showing serious signs of exhaustion and a lack of capacity to solve Madagascar’s growing problems. An opposition party, “Force Vives”, took shape and a long political transition period started. Among other measures the new Mining Code of August 1990 improved the terms for foreign investment.
A new constitution – endorsed by national referendum in August 1992 – was adopted. Legislative elections in June 1993 produced a majority in the Assembly for the opposition party “Force Vives”, which promptly elected a prime minister from its own ranks. A President, Professor Albert Zafy, also from “Force Vives”, was elected in a ballot between eight candidates in February 1993. With two thirds of the vote he easily beat Ratsiraka, who gained only 33%.
Although the problems affecting the Malagasy economy remain very serious, Madagascar’s peaceful transition from a military dictatorship to a parliamentary democracy bodes well for its future.
5.1.2 Population and Culture
History and geography account for the diversity of Madagascar’s population which was estimated at 13,100,000 in mid-1995. The population is increasing at a annual rate of 3.1%, fast outstripping Madagascar’s capacity to feed and employ them.
The majority of Madagascar’s population descends from Malay and Indonesian migrants. They began arriving in the 6th century when the powerful Hindu-Sumatran empire of Srivijaya controlled much of the maritime trade in the Indian Ocean.
These people brought with them the food crops of South-East Asia, so that even today Madagascar’s agriculture resembles Asia more than Africa. These earlier colonists brought with them a strong dislike and suspicion of India which persist to this day.
There are 18 principal ethnic groups on the island. Here below is their distribution (1974 figures):
The dominant ethnic groups, the Merina and the Betsileo, who inhabit the most densely populated central provinces of Antananarivo and Fianarantsoa, are of Asian origin. In the coastal areas live the tribes collectively called “c”tiers” of which the most numerous are the Betsimisaraka on the east coast. These tribes are of African and Arab origin. There is a lingering mistrust between “c”tiers” and Merina-Betsileo people, the old ruling class in pre-French Madagascar.
Population density ranges from more than 30 inhabitants per km2 on the fertile central highlands (where all Madagascar’s gold occurrences are) down to two per km2 on the largely sterile west coast.
French nationals, many married to Malagasy, numbered less than 15,000 in 1986 and their number is decreasing. A minor, but persistent, point of friction between Madagascar and France are some minor islands in the Mozambique channel that are claimed by both France and, reasonably enough, Madagascar.
A Chinese community, numbering about 10,000, is dispersed throughout the east-cost region, where they are principally employed as grocers, small-scale bankers and traders. Also inhabiting the coastal areas are 10,000 or so Indian nationals.
Indians are rather unpopular with the Malagasys because of their clannishness and their wealth, acquired through control of the textile and jewellery trade and urban real estate. Both Indians and Chinese are major players in the vigorous gold smuggling trade out of Madagascar (often through Mauritius), which the Government is all but incapable of controlling.
More than 82% of the Malagasy still live in rural areas, but the towns are inevitably attracting an ever-larger percentage of the fast-growing, under-employed rural population, thus seriously aggravating socio-economic problems. Antananarivo the capital, far from being the gracious, pleasant little city of the ’70s, is now a sprawling city of more than 1,000,000 people, mostly living in very poor conditions. The other six provincial capitals also continue to expand.
The universal languages of Madagascar are Malagasy and French (apart from the vernacular dialect of any particular tribe), which are currently spoken by anybody who has attended primary school. English is understood a little by the most educated levels of the population in the major cities, but not at all in the countryside.
5.1.3 Currency and Banking
The national currency is the Malagasy Franc (MG Fr). In December 1995 the exchange rate was as follows:
1 $US = 4,499.80 MG Fr
1 œStg = 6,967.80 MG Fr
1 DM = 3,038.66 MG Fr
Since 1994 the Malagasy Franc has not been pegged to the French Franc.
Liberalisation of the banking sector has attracted foreign private banks to Madagascar. Banque Nationale de Paris is the main shareholder, owning 55% of Banque Malgache de l’OcŠan Indien (BMOI), which was officially opened in January 1990. Belgian and German banks own 20% of BMOI, and 25% belongs to about 300 Malagasy shareholders.
In 1991 a public investment program (1991-1993), financed by the World Bank, IMF and other international donors, was initiated. The program, which cost an estimated $US 1,000M, again placed emphasis on the liberalisation of trade and domestic sector, the encouragement of foreign and domestic investment, a reduction in the role of parastatal bodies, and increased producer prices.
Following a prolonged general strike in the second half of 1991, however, the program was deferred, pending the fulfillment of certain conditions, which included the transfer of a number of parastatal organisations to the private sector and a reduction of public expenditure.
The general strike of 1991 resulted in severe deterioration of the financial sector, with a major fall in tax revenue and a rise in the budgetary deficit. That is now around 5% of GDP.
As matter of priority the new democratically elected president, Prof A. Zafy, established an economic and financial co-operation committee in 1993 to conduct negotiations with international donors, and resumed an economic program in conjunction with the IMF. The adoption of a number of development projects, which included plans to rehabilitate infrastructure (with the assistance of the World Bank) was also envisaged.
Madagascar’s climate is temperate and rather pleasant; temperatures in Antananarivo are generally between 8§ and 27§ C, with cooler, dryer weather between May and October. The coastal region is tropical with an average daily temperature of 32§ C. The rainy season extends from November to April in the highlands – average annual rainfall is 1,000 – 1,500mm – but is more prolonged on the coast, where annual rainfall can reach 3,500mm.
Geological exploration can be carried out continuously throughout the year.
5.2. AVAILABLE DOCUMENTATION
Madagascar has fascinated a number of authors and researchers (and still does). This has created a wealth of easily accessible backgound information; some of the most interesting works are given in the bibliography of this Database.
Far less accessible is Madagascar’s geological information. Mr H Besairie’s classic, the two-volume “Gites MinŠraux de Madagascar”, is unfortunately out of print. The extensive gold bibliography on Madagascar by French authors (appendix 1 to this Database) is very difficult to access and some items have apparently been lost.
However the modern gold explorer in Madagascar still has (as of 1996) some reliable basic information to guide exploration. Apart from the various works mentioned in the bibliograhy (Chapter 9 of this Database) three sets of maps are strongly recommended for any exploration work in Madagascar.
MADAGASCAR GEOLOGICAL MAPS AT 1 : 1,000,000
By H. Besairie
Projection: Conforme Laborde. The point X = 800km and Y = 400km has for geographical co-ord Lat 21§ & Long. 49§E, Paris.
See Sketch 5/2 in this Database for sheet coverage.
A = North Sheet (Feuille du Nord)
= Central Sheet (Feuille du Centre)
C = South Sheet (Feuille du Sud)
N.B. Only 2,500 printed in 1965 at Antananarivo.
These maps may be purchased from: Service Geologique BP 280 Antananarivo 101 Madagascar
MADAGASCAR GEOLOGICAL MAPS AT 1 : 500,000
Author: H Besairie
Projection: Conforme Laborde. The point X = 800km and Y = 400km has for geographical co-ord Lat 21§ & Long. 49§E, Paris.
See Sketch 5/2 in this Database for sheet coverage.
1 = Diego Suarez (now Antsiranana)
2 = Antalaha
3 = Majunga (now Mahajanga)
4 = Tamatave (now Toamasina)
5 = Tananarive (now Antananarivo)
6 = Morondava
7 = Fianarantsoa
8 = Ampanihy
N.B. Only 1,000 copies printed in 1972, Antananarivo.
These maps may be purchased from: Service Geologique BP 280 Antananarivo 101 Madagascar
MADAGASCAR TOPOGRAPHICAL MAP (AERONAUTICAL) AT 1 : 1,000,000
Projection: Conformal Conical Projection, Standard Parallels 1§20′ and 6§40′ Convergence Factor . 06979
See Sketch 5/2/1 in this Database for sheet coverage.
N6 = North of 15th Parallel
P6 = Between 23rd and 15th Parallels
O6 = South of 23rd Parallel
N.B. Each map is subdivided into four individual maps at 1:500,000 scale.
Civilian users may purchase these maps from the following address:
DMA Combat Support Center ATTN: DDCP Washington DC 20315-0020 USA
These three products are of excellent and still unsurpassed quality. The first two can be purchased in Antananarivo (although the supply will inevitably run out); the third can be ordered in the USA.
The two sets of maps at 1:1,000,000 (geological and topographical) can be overlayed on each other only locally due to a different projection system (the French-generated maps use the now obsolete Laborde co-ordinates system.
If a Geographical Information system is used to generate one’s own maps, IMR strongly recommends using the Conforme Conical Projection used by the US Air Force.
These three documents alone (see sketch 5/2 and 5/2/1) are adequate for reconnaissance work. More detailed geological maps at 1:200,000 are also available at Antananarivo but their coverage of Madagascar is incomplete and several maps are now out of print.
Madagascar’s “Institut GŠographique et Hydrographique National (Foiben-Taosarintanin’i Madagasikara = FTM) publishes a series of maps of Madagascar at the 1:500,000 scale and an excellent, informative, and up to date road map at the 1:2,000,000 scale.
Air photos are available but they are old, subject to restrictions and to tiring beaurocratic haggles. On the other hand, excellent satellite images (particularly the French SPOT coverage) are readily available outside Madagascar and can be conveniently blown up, up to the 1:50,000 scale. IMR strongly recommends their use: the morphology of Madagascar’s highlands, where most of its gold districts are, is ideally suited to satellite-image interpretation. Modern Global Positioning System instrumentation can now assure a level of accuracy not previously available in any published map of Madagascar.
5.3 INSTITUTIONAL AND ECONOMIC FRAMEWORK
5.3.1. The Government
Sketch 5/3 outlines the present political structure of Madagascar. The uncommonly large number of ministries (21) reflects its French political heritage. Historically, the number of these ministries is periodically pruned in times of political reform, then start to regrow immediately afterwards to accommodate the need of political patronage, regardless of the political party in power.
The unusual combination of combining the offices of Prime Minister with the Ministry of Defence is an insurance policy against military coups. So is the fact that the national police reports to the Ministry of Defence (Prime Minister, really) rather than the Ministry of Interior.
This unusual constitutional arrangement has now been tested for only two and half years, but it seems to work. The main area of friction remains between the respective powers of the popularly-elected President and Head of State, and the National Assembly-elected Prime Minister.
The town of Antananarivo is chronically plagued with rumours of coups. This goes back for at least 30 years. The inexperienced visitor is well advised to dismiss them and under no circumstance demonstrate the least interest in the subject.
The Government is now seriously committed to regional decentralisation, with new regional authorities known as Collectivit‚s Territoriales D‚centralise‚s (CTDs) elected by their own special elections. It is impossible to say at this stage if the CTDs will have some control on local mining operations. It is possible, particularly in environmental matters.
Mining and exploration activities remain controlled by the Ministry of Energy and Mining through its two main Departments of Mines and Geology.
Unfortunately, a dualism of function remains in the mining sector with the presence of OMNIS, which operates in the mining field, particularly in oil exploration and chromite production.
OMNIS was created directly by president Ratisraka in 1975 in the heyday of military government. OMNIS originally meant “Office for Military National Strategic Industry”, now renamed to “Office for National Mining and Strategic Industry” and reportd directly to the President.
The status of OMNIS is somewhat anomalous in a civilian government, and Kronsten in 1994 mentioned “reforms urged by the World Bank, which exercises considerable influence on the current coalition government, include the privatisation of the parastatal OMNIS”. To this date (the last quarter of1995) this privatisation has yet to take place.
Other ministries likely to affect any important mining operations are the Ministry of Finance and Budget (export permits, taxation regime etc) and the Ministry of Civil Service (labour contracts and relations).
5.3.2. The Economy
Madagascar was classified by the World Bank in 1992 as one of the world’s poorest countries. In that year, according to estimates by the World Bank, Madagascar’s gross national product (GNP) – measured at average 1990-92 prices – was $US 2,809M, equivalent to about $230 per head.
In 1985-92, it was estimated that GNP per head declined, in real terms, by an annual average of 1.7%, while the population increased by an annual average of 3.1%. Madagascar’s gross domestic product (GDP) increased, in real terms, by an average of 1.1% per year in 1980-92. The growing gap between population and economic growth is obvious.
The rural economy accounts for 80% of Madagascar’s export revenues and supplies most of the raw materials for industry. In 1992 the agricultural sector (including forestry and fishing) accounted for 33% of GDP and engaged an estimated 76% of the country’s labour force.
The production of both food and export crops, except cotton, either stagnated or declined after President Ratsiraka took power in 1975, mainly as a result of the imposition of a doctrinaire form of socialism. The presence of North Korean “advisers” obviously did not help. The imposition of co-operative state farms on a reluctant peasantry also contributed to the agricultural sector’s poor performance.
Between 1980 and 1992 agricultural GDP increased by an annual average of 2.4%, still considerably below the population growth rate.
The forestry sector has been badly neglected, and 81% of domestic fuel needs are supplied by wood and charcoal. In 1991, according to a FAO estimates, about 26% of the land area was covered by forests. A $66M aid arrangement was agreed to at a donors’ meeting in Paris in February to support the first stage of a long-term environmental action plan.
In August 1989 a “debt-for-nature” exchange, the first in Africa, was arranged: the USA gave the Worldwide Fund for Nature $US 1M to buy $ 2.1M of government commercial debts at a 55% discount from a consortium of international banks, and to use the money for environmental projects. This imaginative scheme proved successful and further debt-conversion agreements, involving international organisations, were subsequently negotiated.
Paddy rice is the main Malagasy crop. It is grown by 70% of the population whose basic food is rice (the average annual consumption is about 135 kg per head, the highest in the world).
Paddy rice output in Madagascar averages about two tonnes per hectare. Madagascar, once a rice exporter, has become a net importer since 1982, although improved economic policies can correct this imbalance in the future. Other important staple crops are maize, cassava, bananas and sweet potatoes.
Madagascar’s main cash crops are coffee, vanilla and cloves. The most important is coffee (97% of it robusta, although arabica production is encouraged) which in the 1980s accounted for about 24% of total export earning and engaged 25% of the working population. In some Madagascan goldfields coffee vies with artisanal gold mining in land use, with changes from one activity to the other according to gold and coffee prices.
Madagascar’s coffee production for the 1980s was generally about 82,000 t/y – almost the double the export quota allocated by the International Coffee Organisation (ICO). Madagascar thus had considerable quantities for disposal in the non-quota market.
Madagascar is the world’s largest exporter of vanilla, which accounted for 19% of its total export revenues in 1992, with about 1,000 t/y production. Madagascar operates a highly effective price control system on vanilla with Reunion and Comoros. Production of cloves in the early 1980s was around 10,000-12,000 t/y and accounted for about a quarter of export earnings.
Other significant Malagasy crops are cotton, sisal, sugar, groundnuts, pineapples, coconuts and tobacco.
Industry accounted for 14% of Madagascar’s GDP in 1992; the sector employs only about 3% of the working population – not an uncommon figure for central Africa.
The island’s major industrial centres, other than mines, are located in the High Plateau or near Toamasina port. Food processing accounts for 49% of all industrial value added. Textiles was formerly the second largest sector but it has been now superseded by brewing, paper and soap.
There are cement plants at Mahajanga and Toamasina, supplied with good quality local limestone. However, in the late 1980s average annual production of cement was only about 40,000 t necessitating imports of about 250,000 t/y.; by 1990 production had declined to a paltry 20,000 t.
A fertiliser plant at Toamasina, which began operation in 1985, produces 90,000 t/y of urea and ammonia-based fertilisers. Other industries include the manufacturing of wood products. Most industrial plants in Madagascar have been operating recently at less than one-third of their installed capacity.
In 1986 the government introduced a new investment code, which provided incentives for domestic and foreign private investment in activities outside the public sector, particularly in manufacturing for the export market.
The country’s fifth investment code, enacted in 1990, introduced incentives to attract foreign private investors. This code was strongly opposed by many politicians and local business people.
Rules regarding foreign exchange and the number of expatriates which can be employed have been relaxed and tax incentives were introduced, including a five-year holiday from corporation tax.
A number of export processing zones (EPZ) have been established and have attracted foreign investors from South East Asia, France and Mauritius. Labour is cheaper and corporation laws are lower in Madagascar than in France or Mauritius but the risks are higher for companies producing for export. One common complaint by Asian investors has been the still modest education of Malagasy labourers, as in the rest of Africa.
In the early 1990s the IDA approved a credit of $48M to finance the development of private enterprise through training of personnel, the restructuring Madagascar’s Chamber of Commerce, and the establishment of an investment promotion agency. These initiatives, although unquestionably praiseworthy, had practically no effect on the mining sector.
5.3.3. The Mining Sector
The high French expectation of Madagascar’s minerals at the time of its colonisation (1895) never materialised.
The then vigourous gold production has ceased for decades to be an organised (taxable) activity and does not now contribute to government revenue. The promising coal deposits of Sakoa (a major preoccupation for the French steam fleet of the time) never really took off, the enthusiasm for Madagascar’s uranium was short lived and doomed.
Bulk commodities such as iron ore, bauxite and oil shales were condemned from the start by lack of local industry or export infrastructure. Oil exploration has been particularly disappointing with company after company drilling a few desultory holes in Madagascar’s Karroo formations and then withdrawing. In the ’90s only chromite, graphite and mica survived as organised mining activities and none was particularly wealthy. Madagascar is essentially an agricultural economy.
IMR’s own impression is that Madagascar suffers “exploration fatigue” out of proportion with its objective, and still largely untested, mineral potential. Foreign explorers eschew Madagascar. Original geological work is minimal and no new ideas seem to be generated by an anaemic mining sector. A country that only 30 years ago was one of the most advanced in central and east Africa now languishes behind mosts in ideas, investments and energy; at least in the mineral sector.
The Malagasy Mining Code
In Appendix 2 to this Database is given the (barely readable) official version of Madagascar’s latest Mining Code (Law No. 88-06) of August 26, 1988. This bulky document consists of 121 articles. It has been drafted for the stated objectives of:
1) Creating a favourable climate, from the juridic, fiscal, technical and social perspectives, to attract new investment in the [mining] sector and therefore to complete similar measures taken in the whole national economy;
2) Decentralising the [mining] administration for better serving the general interests;
3) Increasing the professionalism of the [mining] sector, putting in places a set of clear and appropriate rules in a way to offer a framework for the rational and optimum development of national mineral resources.
This document unquestionably improves the terms for foreign investors but it still remains an untested document, as Madagascar has failed to attract large new mining investors. Since the nationalisation of the chromite industry in 1976 no major international mining firm has been operating in Madagascar.
In addition, some important new mineral projects (oil, coal and petroleum exploration) have been negotiated directly with the parastatal OMNIS organisation and not with the Ministry of Energy and Mining (see sketch 5/3); this has tended to create some confusion.
In IMR’s opinion the 1990 mining code is perfectly adequate and flexible enough to open serious negotiations on exploration for large gold projects in Madagascar. Madagascar’s Minerals
Chromite and graphite are the only minerals currently exploited in substantial volumes in Madagascar. Their contribution to the GDP is less than 1%.
Madagascar is the world’s tenth largest chromite producer with output at around 110,000 t in 1994, down from about 200,000 t/y in 1976 when OMNIS took over from Pechiney. This chromite production, negligible by South African standards, is however larger than the production of Australia, Japan, US and China combined.
With chromite prices (April 1995) about $ 70-80 per tonne Madagascar’s total chromite production is only worth about $9,000,000. This is equivalent to about 708 kg of gold or one fifth of Madagascar’s estimated “artisanal” gold production of 3-4 t Au/year.
Arguably then, even now gold is by far the most important mineral product in Madagascar, even if the benefits from it do not reach the population at large. Which is, of course, deplorable.
Graphite production, the second largest “official” mineral product in Madagascar, totalled 10,600 t in 1992, down from 18,500 t in 1990.
The graphite industry in Madagascar is a very old and tired one. Without new investments, Madagascar’s graphite industry will be seriously affected by the competition of its more aggressive neighbours. These neighbours – in a geological sense at least – are starting to exploit the Malagasy type of graphite in their own territory: the Ancuabe mine (5,000 t/y) in Mozambique, the Graphtan Merelani mine (15,000 t/y) in Tanzania, the Maranamadurai mine (15,000-20,000 t/y) in Southern India. All these mines were commissioned in the period 1994-5 and they are producing the same product (large flake graphite, >98% C) as Madagascar and therefore significantly eroding Madagascar’s world market share.
Along with Canada, Madagascar is one of the world’s few producers of phlogopite, with exports of 1,800 tonnes in 1990, mostly by semi-artisanal operations around Tolanaro-Amboasary in the extreme south-east of the island. A small percentage of the production is in the form of sheet mica.
Madagascar also produces marble, a variety of construction materials, soil conditioners, and semi-precious stones (amethysts, tourmaline, beryls, and garnets).
Bauxite deposits at Manantenina in the south east are estimated at 100 Mt and have been assessed for decades by French, Soviet and more recently Italian and EU experts. The bauxite quality is acceptable (barely: 38% Al2O3) but the total lack of infrastructure and Madagascar’s fragile environment work against its exploitation.
The coal deposits of Sakoa have been known for more than a century and the stated reserves are >100 Mt. A number of companies including the Australian BHP have carried out evaluation in the past but, once again, lack of infrastructure would make exploitation uneconomic.
The largest project under consideration is the extraction of ilmenite from an area of rainforest and sand dunes at Toalagnaro on Madagascar’s south-east coast.
Under a letter of intent signed in November 1994 by Quebec Iron and Titanium (QIT, a subsidiary of the RTZ group) and the state mining group OMNIS, extraction could take place for 30 years and it is estimated will earn up to $550 million.
The project will involve the construction of a new port and other infrastructure. The project has attracted considerable flak from international environmental groups, concerned – among other things – about the biodiversity of Madagascar’s rainforest.
In the case of Malagasy mineral sands the alarm seems premature.
Madagascar’s ilmenites present several extraction problems (Bartle, 1988). The deposit is low grade and the ilmenite is of sub-standard quality. Its unacceptably high Cr2O3 and manganese content and highly radioactive (Th/P) contaminants will require costly treatment processes before a commercial product can be obtained.
These deposits have been evaluated for decades by a number of companies and individuals (including the writer), with mixed reports. It would seem that Malagasy ilmenite is a rather atypical ore and apparently only suitable for the production of a chlorinatable slag – not QIT’s preferred route for its products. It is therefore doubtful that Madagscar’s ilmenite will be exploited any time soon (IMR’s opinion). The fact that Malagasy authorities should insist on a vigorous and conclusive evaluation of its mineral sands (as Mozambique is doing) is entirely a different matter.
5.3.4. The gold sector
In Madagascar’s socialistic climate of 1975, the country’s gold industry was nationalised (Anon 1994). This was largely a symbolic move as official gold production in the 1970s had dwindled to 2-4 kg/y.
In reality the government did not have the resources to implement any policing of Malagasy goldfields and as soon the gold prices picked up at the end of 1970s “artisanal” gold production started anew.
The distinction between illegal and “artisanal” gold production is a thorny one for any developing country, and particularly for Africa. The authorities are aware that “artisanal” gold mining is not either a sustainable or socially constructive activity but they are impotent to regulate it.
Lack of information and an inadequate mining environment has deterred most foreign companies from seriously committing themselves to gold exploration in Madagascar.
The Government’s half-hearted attempts to entice foreign capital towards organised (taxable) gold production in Madagascar came to little.
The public become seriously worried in 1993 when the government gave a little-known Swiss group exclusive nationwide gold and prospecting rights for 25 years, in return for the placing of up to $US2 billion in discounted promissory notes from the government (MJ Annual Review, 1995). The scheme – of very dubious legal validity in any case – was shelved. If anything, this episode proved the surprising degree of naivety of the Malagasy authorities on mining matters.
In late 1994 the government decided to form a gold trading agency through which the ministry of Energy and Mining would buy the output of private prospectors (see appendix 3). This agency will deposit sale proceeds with Malagasy central bank and it is designed to boost official revenue at the expense of smuggling, particularly to India and mainland Africa.
Similar schemes have been implemented in other parts of Africa (ie. Tanzania, Angola, Zaire, etc). The writer – who has participated in several UN or government-sponsored seminars on similar matters – is unconvinced of the wisdom of such a move. The native gold producer will sell gold to a government agency only if the price offered is superior to the market one (only China manages to buy most of the gold from its miners at a significant discount from the international price, thus creating a commercially viable agency).
In other words, to persuade individual miners to part with their gold a government has to subsidise gold mining. This could mean subsidising an illegal, undesirable and unsustainable practice with no return for the Government.
The problem is not new. It is occurring in dozens of African countries, in Latin America, in Papua New Guinea. Each country will react to this problem (because a problem it is) according to the possibilities and its own political and cultural framework. This is not the place to elaborate on this.
However, it would not seem that individual miners would represent a direct threat to a major gold explorer in Madagascar. Such an explorer is traditionally attracted by large – and therefore comparatively low-grade – gold deposits with a substantive vertical expression, often requiring sophisticated recovery plants. Superficial or alluvial gold deposits are not favourite targets with such investors. Of 16 major new gold projects under development worlwide in 1995 (Thomas, 1995), none was alluvial.
It is IMR’s firm opinion that large-scale gold deposits have simply not been sufficiently explored in Madagascar and, at this stage of knowledge, they constitute a very good potential target.
Madagascar’s mountainous topography has traditionally hindered communications. In 1991 there were 34,750 km of classified roads, of which 8,540 were main roads and 18,380 km secondary roads. Only 5,350 km were paved. The rest of the road network is occasionally unusable in the wet season (November-April) unless using 4WD vehicles.
In 1989 the European Development Fund (EDF) granted $10M for road rehabilitation in the north and west of the country. In mid-1994 a program to rehabilitate a further 500 km of main roads, at an estimated cost of $8 M, was under consideration by the EDF.
The excellent “Carte RoutiŠre” of Madagascar at the scale 1:2,000,000, issued in 1990 by the IGM (Insitut G‚ographique National) and available in any major bookshop, is all one needs for a reliable and complete guide to road transport in Madagascar.
It should be stressed that all the major Madagascan goldfields (with the possible exception of Andrarona) are easily accessible with standard 2×4 cars rented from commercial agencies in Antananarivo.
5.4.2. Air transport
Domestic air services have always been important in Madagascar, on account of its size, difficult terrain and often poor quality of other forms of transport. There are 211 government-approved airfields (see “Carte RoutiŠre de Madagascar” for their location), two-thirds of which are privately owned. The only international airport is at Antananarivo.
The national airline, Air Madagascar, is two-thirds owned by the government and one third by Air France. Under the government’s new liberalisation measures, Air Madagascar lost its monopoly on domestic services and in 1992 its heavily subsidised external services were substantially reduced.
Any goldfield in Madagascar is a convenient distance (30-80 km) from an official airport, and several air charter companies in Antananarivo offer reliable services. Air Madagascar links most of the major townships with a fleet of Boeing 737 and Twin Otters; the timetable is given in appendix 4. The service is totally reliable.
Charter plane and (slightly more difficult) helicopter hire are available in Antananarivo at prices comparable with international standards.
Adequate telephone and facsimile facilities are available in all major towns. Communications between Antananarivo and the rest of the world do not present any problem. Communications by telephone within different localities in Madagascar can at times be difficult.
The use of two-way radios is restricted and requires a special permit.
Practically every village in Madagascar is equipped with a small post office. The largest ones have telephone connections.
Railways and maritime transport play only a very subordinate role in gold mining and therefore will be dealt very briefly. Madagascar has 1,095 km of railways. Three lines in the north of the country primarily serve the capital, while the fourth, in the south, links Fianarantsoa to Mankanara port.
In 1986 the World Bank agreed to lend $12m to finance the rehabilitation of the northern railway and its extensions for a further 40 km.
Toamasina and Mahajanga, the principal seaport, suffer from a lack of storage space and equipment. Toamasina port handles about 70% of Madagascar’s foreign trade and was in the process of being enlarged and modernised, until 80% of the port was destroyed by a cyclone in March 1986.
Germany, France, the UK and the World Bank are financing a ongoing project to rehabilitate 10 Malagasy ports. Toamasina is independently managed but the other ports are operated by the Malagasy Ports Authority. The parastatal SocietŠ Malgache de Tranports Maritimes has four ocean-going ships, while coastal shipping is mostly handled by private firms. The country has a total of 18 ports handling a little less than 1 M tonnes of freight a year.
6.1. General information
Practically all geological work in Madagascar took place during the French colonial time (1895-1960) – the golden age of Madagascar’s geology. Many first-class geoscientists did their doctorate theses on various aspects of Madagascar’s geology or spent years in the then vigorous Madagascar Geological Survey (Service Geologique). This service was headed from 1930 to independence by the still legendary Henry Besairie.
Systematic geological mapping at various scales started in 1926. The geological map at 1:200,000 was completed in 1951 and in 1960 the geological maps at 1:100,000, covering almost two-thirds of the country. Some of these maps are unfortunately out of print.
Between the two World Wars intensive exploration took place, identifying deposits of coal, bitumen, graphite, mica, several precious stones, cement-quality limestone, glass-quality silica sand and many other commercial minerals.
Immediately after WW2, exploration for oil and uranium was actively undertaken, respectively by the S.P.M. (Societ‚ des P‚troles de Madagascar) and the C.E.A. (Commissariat … l’Energie Atomique). For a short time Madagascar was a uranium producer, exporting several hundred tonnes of urathorianites from the T”lan”ro (then Port Dauphin) region.
Since the end of colonial rule geological mapping and mineral exploration decreased dramatically as any computeried literature search can confirm: less has been published on Madagascar’s geology in the 35 years after independence than in the last five years before independence. As a consequence, and particularly in the non-French speaking world, the geological understanding of Madagascar has remained grossly inadequate. This is despite the growing interest in Madagascar because of its pivotal position in Gondwana (Katz and Premoli, 1978; de Wit, 1988; Kroner, 1991).
This information gap is actually widening. While more and more literature is generated on Madagascar’s geological neighbours (East Africa, south-west India, Sri Lanka, Antarctica), very little new information is coming from Madagascar.
Another reason for the relative obscurity of Madagascar’s geological and mineral endowment is that although a bibliography on this subject lists several thousand titles (Besairie, 1971), this literature is not generally available.
Mostly it consists of internal reports by Madagascar’s Service de Mines and Service Geologique, and they are difficult to obtain even in Antananarivo. Indeed, the principal sources of information for this Database are Besairie’s various maps and publications (some of them now unfortunately out of print), supplemented by modern publications on Madagascar’s regional geology and metallogeny.
6.2. Madagascar’s geomorphology
The geomorphology of Madagascar reflects its underlying geology and either one can be glanced at in sketches 5/1 and 6/1.
The mountainous backbone of the island consists of Precambrian rocks. To the east lies a narrow coastal plain defined by Cenozoic normal faults which strike NNE-SSW, and impart a striking linearity of coastline.
The western shore is less regular. The Morondava basin lies south of Tanjona Vilanandro (former Cap Saint Andr‚). To the north of this cape is the Majunga basin, and still farther north is the Antsiranana (formerly Diego Suarez) basin. These three sedimentary basins are largely in faulted contact with the Precambrian. The cuesta-forming beds dip gently seawards.
This area of Madagascar is sometimes called the “Karroo corridor” and, similarly to other Karroo regions of Africa, it hosts interesting hydrocarbons, coal and uranium deposits (Premoli, 1995).
There are unexplained lacunae in Madagascar’s geological records. After the Pan-African event, principally consisting of thermo-metamorphism around 550 MA, there is essentially no record of Phanerozoic rocks until the late Paleozoic (Karroo formations). This interval must include the plant-bearing rocks in which Devonian or Carboniferous flora has been identified but whose outcrops have not yet been found.
Late Paleozoic and younger rocks in the marginal basins show a succession of marine and non-marine events. But since sedimentary basins play no role (alluvial deposits excluded) in Madagascar’s gold metallogeny they will not be discussed here in any detail.
All the known primary gold mineralisations in Madagascar predate the breaking up of Gondwana, making regional tectonic models (India, Mozambique, Tanzania) particularly relevant. Equally so is a good understanding of Madagascar’s Basement complex.
6.3. Madagascar’s Basement complex
Precambrian rocks form about two-thirds of Madagascar. They are exposed continuously from Tolanaro in the south to Antsiranana in the north (see sketches 5/1 and 6/1). These Precambrian terrains are often referred to as the Basement or the crystalline Basement of Madagascar.
The metamorphic grade of this Basement is generally high, and for almost the whole island varies between the amphibolite and the granulite facies (Premoli, 1979). Greenschist facies are comparatively rare. The tectonic history and geology of Madagascar presents several similarities with both eastern Africa and peninsular India.
Madagascar’s Basement underwent three major tectonic periods which can be summarised as follows (from the youngest to the oldest):
After 300 MA Era of platform cover and great tectonic rift
Between 2,600 and 300 MA Era of intercratonic orogenesis and great magmatic reactivations
Before 2,600 MA Era of cratonisation
Madagascar’s Basement rocks have been divided into three major systems. From the youngest to the oldest these are:
The Vohibory System
The Graphite System
The Androyen System
Each of these systems has been subdivided into several groups. These groups usually have outcrops in different locations and consist of different lithologies. As a result the assignment of a group to a particular system and the age relationship between groups in one system is still to be determined with confidence in most cases. This problem is exacerbated by the general lack of modern geochronological data in Madagascar from the last 35 years.
Madagascar’s Basement rocks have been intruded by several igneous episodes. Some of them may have contributed to the remobilisation and concentration of gold (model a4, see chapter 6.5). The principal intrusive phases are indicated below (from younger to older):
90 MA: Cretaceous intrusive complex of Antampombato, consisting of gabbros, syenites, pyroxenites, pridotites and possibly the Itremo carbonatites
500 MA: pegmatites ) ) of the Pan-African event
550 MA: granites )
850 MA: granites (poorly known) associated with charnokites
1125 MA: granites and syenites of Ambatofinandrahana intrusive complex and associated nephelinitic and gabbroic complexes. It compares with the Kibarian orogeny in other parts of Africa
1400 MA:Andrianamena basic complex, including also ultrabasic rocks (gabbros, pyroxenites, peridotites) which have been metamorphosed to orthopyroxenites, orthoamphibolites, talc- schists and serpentinites
A systematic and detailed study beween granitic intrusions and gold mineralisations (which has proved highly successful in Australia) has never been attempted in Madagascar. Indeed only in the last eight years has improved analytical and computer techniques made such study meaningful. Any serious gold explorer in Madagascar should give early attention to gathering data in this field.
6.3.1. The Androyen System
This system is the oldest on the island and consists of highly metamorphosed, often granulitic, rocks. This system is sometimes referred to in French literature as “Migmatitic-leptynitic Lower Complex”. The Androyen system outcrops are principally in the southern part of the island where they occupy a roughly triangular area which extends northwards about 450 km (see Plate 1).
The Androyen System has been broken into three groups (Besairie, 1964), from the youngest to the oldest:
A3 : Ampandrandava Group – Gneisses, Pyroxenites, Charnokites, Marbles
A2 : Tranomaro Group – Pyroxenites, Gneissess (Ca – Mg), Leptinites, Marbles
A1 : Fort Dauphin (now T”lan”ro) Group – Leptynites with cordierite
Apparently, none of Madagascar’s gold districts occur within the Androyen system and therefore the interest of this system for gold exploration is rather limited.
6.3.2. The Graphite System
Rocks assigned to this system form the greatest part of Madagascar’s Basement – and they are also the most consistently mineralised in gold. The system is characterised by the presence of graphite in greater or lesser abundance. The intensity of metamorphism varies according to location; the different regional groups are still defined by their metamorphic grade rather than their stratigraphic relationship.
Besairie (1964) distinguishes four groups within the Graphite System, some of which are closely associated with gold districts. From the youngest to the oldest:
G1 B4 : Andriba Group – migmatites and gneisses without graphite
] B3 : Ambatolampy Group – micashists and gneisses ( with graphite ( G2 ( B3 : Manampotsy Group – gneisses and migmatites ( with graphite ( ( B1 : Vohibory Group – Leptinites, gneisses ( amphibolic, amphibolites, marbles.
A more simple distinction can be made between migmatites without graphites (G1) and those that are graphite-rich (G2). This easier differentation is particular relevant to gold exploration as all the presently kown mineralisations occur in the graphite-rich zones of the Graphite System, especially near Antanananrivo (see Plate 1, in this Database).
6.3.3. The Vohibory System
This system was first defined on Vohibory Mountain in the South-western part of Madagascar, hence the name. Characteristic of the Vohibory System is the abundance of amphibolites in the form of ortho-amphibolites, associated with basic to ultrabasic intrusions also metamorphosed to various degrees. It would seem, however, that what the French geologists call an amphibolite their Anglo-Saxon colleagues would call gneiss.
Besairie (1964) distinguished 10 groups within the graphite system, some of which are closely associated with specific Madagascar gold districts. From the youngest to the oldest:
C10 : Daraina Group – Amphibolites with epidotes, gneiss, granodiorites
C9 : Sambirano Group – Gneisses, quartzites, marbles
C8 : Antonigil Group – Epidote-rich migmatites
C7 : Ambodiriana Group – Feldsphatic micashists
C6 : Maentavanana Group – Greenschists, magnetiferous quartzites, amphibolites, gneiss
C5 : Beforona Group – Amphibolites, migmatites
C4 : Manajary Group – Micaschists, gneiss, greenschists, migmatites
C3 : Amborompotsy Group – Amphibolic gneiss, migmatites, marbles
C2 : Malakialina Group – micashists, marbles, quartzites
C1 : Vohibory Group – Leptynites, amphibolic gneiss, amphibolites, marbles.
A tentative correlation between this geological description, the Gondwana one and BRGM’s classification (edited and improved) is given in Table 2.
IMR would also like to bring to the attention of potential gold explorers two intriguing groups in the Vohibory System:
i) C6, or the Maentavana group, with its most unusual magnetite-gold quartzites (nine alluvial occurrences listed in Table 6). Their primary source could well be of economic interest in its own right for the modern explorer.
ii) C4, or the Manajary group, what the French geologists have called greenschists. It may very well be metamorphosed greenstone belts in the Vohilava-Ampasary gold district.
6.3.4. Concluding remarks
Of the three Archean “Systems” recognised by Besairie the Vohibory and the Graphite ones are auriferous, the Androyen is not. Within the Graphite System the gold districts occur exclusively within its graphite-rich parts and not in the much more extensive graphite-poor areas (see Plate 1). If a plausible rationale can be advanced for the lack of gold potential for the graphite-poor groups within the Graphite System, then the area prospective for gold in Madagascar could be almost halved.
Besairie considers the Betsiriry gold district as Archean (Vohybory System), but BRGM considers it as Proterozoic (see sketch 7/2). However, this argument has little relevance with the practical aspects of gold exploration in Madagascar at this stage.
In Madagascar there are obviously a lot of periods of tectonic-thermal overprints. Besairie sees three major periods of gold mineralisation (from the youngest to the oldest):
140 MA – equivalent to Upper Cretaceous 1,125 MA – equivalent to Precambrian B (de Wit, 1988) 2,140 MA – equivalent to Precambrian C (de Wit, 1988)
IMR is sceptical about the period of mineralisation connected to the Upper Cretaceous period. This time corresponds to tensile tectonics with associated alkaline intrusions, and particularly carbonatites, throughout all Gondwana. These alkaline intrusions have important, and occasionally economic, mineralisations (Cu, Fe, RE, Nb, F,) but so far no gold has been found in anything near economic grades.
The impression (IMR’s opinion) is that the 140 MA tectonic episode simply remobilised and reconcentrated pre-existing gold mineralisations in the Basement, but did not introduce any significant gold from mantle sources.
An attempt by IMR to conciliate the various different Precambrian stratigraphies of Madagascar (Besairie, 1964, 1969; Jourde, 1971; Hottin, 1972; de Wit 1988) has been totally unsuccessful.
Considering that practically no new mapping or geochronological work has been carried out for more than three decades and that Besairie’ geological maps (particularly the ones at the scale of 1:500,000, see sketch 5/2) are the most useful on the field, Basairie’s broad interpretation of Madagascar’s geology has been retained throughout this Database.
In the table below a comparison is given between the two main interpretations of the age of Madagascar’s known gold districts:
TSARANANA Archean, Fe-Ca-Mg series Vohybory System
MAENTAVANA Archean, Fe-Ca-Mg series Vohybory System
BETSIRIRI Proterozoic Vohybory System
ITASY Archean, sialic series Graphite System
AMBOSITRA Archean, sialic series Graphite System
VOHILAVA Archean, sialic series Vohybory System
BEFORONA Archean, Fe-Ca-Mg series Vohybory System
ANDRARONA Basement/sedimentary ? Vohybory System
VAVANTENINA Archean, sialic
series Marble Series
This table has been expanded and elaborated on in Table 3, given in appendix to this Database.
How to usefully translate typical French concepts such as the sialic series (Series “silico-alumineuses”) and the Fe-Ca-Mg Series (Series “ferro-calco-magnesiennes”) into the more familiar western terms – calc-alkalic sequences, komatite-tholeiite, felsic volcanics, etc – will no doubt keep many geologists busy in future.
6.4. Metallogeny of Madagascar’s gold.
From what is known, all the primary gold deposits of Madagascar belong to the “mesothermal lode-gold” deposits as defined by Hodgson (1993).
The reason why Madagascar’s gold deposits are seldom or ever mentioned in the numerous review papers on the world’s gold deposits is that very little is known about them. But even a cursory examination of now very obsolete literature shows that these deposits definitely do not conform to epithermal, volcanogenic massive sulphides, quartz-pebble conglomerate or porphyry-style gold deposit models.
Here below are the criteria that match conventional mesothermal lode-gold deposits with Madagascar’s own gold deposits:
1. The deposits are mostly quartz-vein related;
2. They occur in metamorphic terrains of all ages, not excluding high-grade metamorphic terrains;
3. Minerals commonly associated with gold are pyrite (less commonly pyrrhotite), base metals sulphides, arsenopyrite, tourmaline and molybdenite;
4. Mineralisation may occur within most rock types but typically in quartz veins, veinlet systems, or as disseminations in heavily tectonised zones;
5. Most mineralisations are hosted by, and always related to, steeply dipping reverse faults and shear zones;
6. At a regional scale, the mineralisations occur in association with major transcrustal fault zones and small felsic alkalic and trondhjemitic intrusions.
All these conditions, suggested by various workers in the field (Kirkham, 1993), have been verified for Madagascar’s gold mineralisations. But information is seriously lacking in the following areas:
A. Fluid inclusions (presumably CO2-bearing and with relatively low salinity). There is no data whatsoever on Madagascar’s deposits;
B. Stable isotope data – presumably in the range of +10 ë O per mil (Kerrich, 1989). There is no data whatsoever on Madagascar’s gold deposits;
C. Geotectonic environment – virtually all the papers on Madagascar’s gold metallogeny predate the acceptance of tectonic plates as a major ore-forming process. Particularly the association of mesothermal gold deposits with major trascrustal faults (Hoffman 1991). Here a considerable amount of field data exists but it needs a total reinterpretation, particularly utilising modern satellite imagery.
It is obvious that any serious gold exploration in Madagascar should be aimed at filling the above lacunae and putting their regional metallogeny into a modern prospective.
However, some general considerations can already be put forward.
Archean lode gold deposits similar to the ones found in Madagascar account for approximately 18% of the world’s gold production. Exploration for this type of deposit has increased dramatically during the last 10 years, particularly in the Archean shields of Canada and Australia and, to a lesser extent, in those of Southern and western Africa, Tanzania, Brazil and Venezuela. This current phase of exploration has produced numerous discoveries, including several major deposits. There is no reason, at the present level of knowledge, why this could not also be the case for Madagascar.
Until 1983, the great majority of the Archean lode gold discoveries in Canada and in Australia resulted from surface prospecting. Virtually all of the remainder were discovered by the drilling of mine extensions or geophysical anomalies.
Exploration success in the 1980s followed similar strategies, with considerable emphasis placed on old mines. The Hemlo deposit (80 Mt with an average grade of 7.7 g/t Au), among the outstanding lode gold discovery of the 1980s, had a history of exploration and minor development dating from 1869 (Hodgson, 1993).
The West Australian gold rush at the end of the last century was led by prospectors and culminated in the discovery of the Kalgoorlie deposits in 1893. The current gold rush (1978 to the present) has seen the re-evaluation of many old gold occurrences, in most cases leading to new discoveries. The economic viability of the new discoveries is strongly influenced by sustained gold prices and new bulk-mining and processing technology, particularly where ore occurs in the oxidised or lateritic profile as is unquestionably the case in Madagascar (see sketch 6/4).
A similar focus on old prospects and new technologies has formed the basis for recent gold mine developments in Zimbabwe, Brazil and Ghana: all major and well-established gold producers.
This emphasis on re-evaluating old prospects when exploring for lode gold deposits suggests that conceptual theories or genetic models have so far had little impact (Hodgson, 1993). This is going to be particularly true for Madagascar with the imperfect and obsolete knowledge of its geology.
Perhaps the most important empirical feature that has recently emerged in the exploration for lode gold deposits is the association with subvertical structures, particularly shear zones.
The style of structure varies from brittle to ductile and shows a good correlation with the metamorphic grade (the “front de migmatites” often quoted by Beasairie), the degree of penetrative deformation, the style of veins, and the silicate and sulphide minerals.
Colvine et al., (1988) has schematically represented these features in a diagram that seems very well suited to guide field exploration for lode gold deposits in Madagascar. It is given in sketch 6/4. Other sensible exploration clues on how to proceed with lode-gold deposits of the Madagascan type are given by Hodgson (1993) in both his paper and extensive bibliography.
6.5. Classification of Madagascar’s gold deposits
The latest published classifications of Madagascar’s gold occurrences and deposits has been given by BRGM (1985). For simplicity a very similar classification is maintained here, but with some adjustments to make it more readily understandable to Anglo-Saxon readers, and to accommodate IMR’s own opinions. Sketch 6/4 summarises schematically these gold deposits.
6.5.1 Primary deposits:
Madagascar’s primary gold deposits, with the exception of the baryte veins of the Betsiaka at the contact Basement and Permo-Triassic sediments in the extreme north-east of the island, all occur in the Precambrian metamorphic terrains (gneiss or migmatites) as veins of gold-bearing quartz, or finely disseminated in the various facies of the crystalline schists.
a) Archean primary deposits
These are the most interesting deposits. They occur mostly as quartz veins interstratified into high-grade metamorphic terrains. There are a total of 105 recorded primary deposits in Madagascar (Table 7).
a1 – Associated with amphibolitic series and basic metamorphic rock (some of them could actually be greenstones). Type examples: Alaotra, Ampasary, Andrianema, Maevantanana. There are at least 13 recorded deposits of this type, particularly in the Maevantanana, Vohilava-Ampasary and Beforona gold districts (Table 7, this Database);
a2 – Associated with magnetite-rich quartzites. Type examples: Maevatanana, Antananarivo region, possibly Andrianema and Beforona-Alatroa. This is a comparatively rare type of deposit (Table 7, this Database), but of obvious interest for large, low-grade resources utilising modern (wet magnet separation) techniques. Sometimes these deposits form their secondary equivalent: auriferous magnetite alluvions (Ankerika, Table 5);
a3 – Associated with the sialic series of the type Ambatolampy-Andriba (quartzites, gneiss, migmatites, Al-rich micaschists – often graphitic). Type examples: Ambatolampy, Andriba, Antananarivo-west, the series of Sahantana and Vavantenina, and possibly the series of the Vohilava-Ampasary gold district. There are at least 34 recorded deposits of this type, particularly in the Itasy, Ambositra-Antananarivo and Vavatenina gold districts (Table 7);
a4 – To the three types described above one can overlay another type, linked with later granitic intrusions which locally effect all the above styles of mineralisations. These deposits can take the form of peri-batholitic veins, stockworks and skarn-type mineralisations. It is thought (BRGM, 1985) that these intrusion-linked gold remobilisations can constitute the most favourable environment for gold deposits. There are at least 27 recorded deposits of this type, particularly in the Vohilava-Ampasary and Andrarona gold districts (Table 7).
b) Proterozoic primary deposits
These deposits are associated with micaschists or quartzite facies of the “schist-quartz-limestone” series (S‚rie shisto-quatzo-calcaire) and remobilised either by regional or contact metamorphism. They generally consist of auriferous sulphides. More than 27 such deposits have been recorded (Table 7). Two type examples are the best known:
b1 – Betsiriry (east of Miavindrazo) where gold occurrences are particularly frequent in the transition zone between the migmatitic gneiss and the epimetamorphic “schist-quartz-limestone” series (the “front of migmatites” of the French authors).
b2 – The region of Itea where gold occurs in Si-rich skarn around the granitic intrusion of Itea (see sketch 7/8).
c: Mesozoic gold deposits
c – Deposits associated with the Permo-Triassic tensional tectonics. These are “real” gold veins, existing in the quartz-baryte filling of the fractures, with free-milling gold and associated sulphides. This type of deposit has so far only been found in the Betsiaka gold district to the extreme north-west of the island. Eleven deposits have been described (Table 7).
6.5.2. Secondary deposits
These deposits form near the meteoric alteration of the primary deposits and the reconcentration of gold by surface waters, This alteration often tends to lateritise the primary gold-bearing formations which can reach economic grades.
Aa – Eluvial deposits. Here the secondary material has been transported along slopes, generally only short distances. Gravity concentration can form locally exploitable deposits even if the primary gold sources are very low grade. More than 50 such deposits have been recorded. These deposits often occurs in the same gold districts as deposits Ac and Ab.
Ab – Old alluvial deposits where the gold-bearing alluvions are more or less consolidated, are in fossil terraces along present valleys. Type example: Ampasary River (sketch 7/12). Several tens of such deposits have been recorded (Table 7);
Ac – Present day alluvial deposits. The auriferous sand and gravels are the actual river beds. These have been traditionally the easiest deposits to exploit. More than 80% of Madagascar’s total gold production has originated from these deposits (Besairie, personal communication 1976). Type example: Ambositra-Antananarivo and Vohilava-Ampasary gold districts. More than 80 such deposits have been recorded (Table 7). Table 2 list some of the largest Malagasy rivers with extensive alluvial gold.
L – “In situ” gold-bearing laterites. This type of deposit has been added to the above classifications by IMR given the increasing importance of these potentially large, low-grade gold deposits in lateritised Precambrian terrains (i.e. Boddington in W.A. = 428,000 t/y Au). This is still a speculative type of deposit in Madagascar but of considerable potential. Type example: Ranomandry, Tainangidina in the Maevatanana gold district.
7. GOLD IN MADAGASCAR: THE FACTS
7.1 History of gold mining
7.1.1 To 1895
Contrary to other east African countries, particularly Ethiopia and Eritrea, gold was not exploited in Madagascar until comparatively recent times.
The first recorded gold discovery in Madagascar was in 1845 by J.Laborde, more than 50 years before the French annexation of the island. Laborde, a French adventurer and adviser to the Malagasy royals, is a legendary figure in Madagascar’s history. The discovery took place during the annual royal hunt in Maevatanana.
Perhaps understandably, gold mining was immediately discouraged by the Malagasy government. The two Malagasy contemporary legal codes (of the years 1868 & 1881) under queen Ranavalona II punished any gold digger with 20 years’ imprisonment. It was only in 1883 under Queen Ranavalona III that gold exploitation was permitted, but by the government only.
The government’s gold exploitations were initially largely manned by the compulsory corv‚e system used for public works (noblemen were excepted). Thousands of people were employed. The first kilogram of gold was produced in 1884 in the Ambositra district, possibly from Itea mine. In 1885 Madagascar’s gold production had reached 75 kg (2,411 oz) in the Maevatan…na region alone.
The first non-government concession was given to the French entrepreneur Suberbie in 1886, once again in the Maevatan…na district.
In 1988 a Mr Rigaud operated, on behalf of the Malagasy government, a series of plants to the south of the capital Antananarivo: Behenjy, Ambatolampy and the rich alluvions of Androka, Andraikibo, Hatsara and many other rivers, which are still artisanally exploited today.
The same year Mr Savaron started the exploitation of the Ikopa (12 kg of Au in 34 days). In 1894 there were more than six legal European gold concessionaires in Madagascar, including a Mr Harrison Smith in the Antsianaka goldfield and Colonel Shervington in Ariovonimano. But the French annexetion of Madagascar in 1895 discouraged Anglo-Saxon concessionaires.
By 1900 gold production in Madagascar was taking place in at least eight major gold districts with a robust production of 1,114 kg (35,820 oz) of gold, mostly from the Mananjary district (see table 1).
With the exception of the Boer republics (Transvaal and the Orange Free State) this steady and rapidly increasing gold production was unprecedented in Africa at the time. The perceived mineral wealth of Madagascar played an unquestionable role (Grandidier G., 1987; Lacroix, 1900; Gallieni, 1901;) in the French government’s decision to grant Madagascar “protectorate” status in 1895. One year after that the protectorate became a colony.
7.1.2 From 1895 to 1960
The French government’s high expectations of Madagascar’s mineral potential (not only gold but coal, gems and other materials) seemed justified at first.
The gold production easily doubled to 2460 kg (79,100 oz) in 1904. In 1906 the discovery of the large and easily winnable deposits of Andavakoera in the extreme north of the island pushed Madagascar’s gold production to around 3 t/y, then on to an all-time high of 3.697 kg (118,874 oz ) in 1909.
By that time Madagascar was by far the largest gold producer in the enormous French colonial empire.
French interest in Malagasy gold is reflected in at least 44 technical publications, some by the most influential French geologists, on the subject in the period 1900-1910 alone (see Appendix 1).
Most of Madagascar’s gold production at the time was coming from rich but “unsustainable” alluvial and eluvial deposits.
The French colonial authorities were obviously proud of introducing modern and efficient mining methods in Madagascar, but disappointments quickly followed.
In 1904 a steam dredge was launched on the Tsiribihina river. This dredge never worked properly and was abandoned near Miandrivazo. Other dredges were tried, without success, on the Mananjary and Ikopa rivers. Only the plant of Andavakoera with five batteries of five hammers each and several amalgamation tables functioned for a few years, but with very high costs.
Essentially a Madagascan alluvial field had a life span of 15-20 years before the production dwindled to few kilograms/year produced by single operators or very small syndicates. Generally cash crops then took place on the old goldfields.
Like most of colonial Africa production dwindled during and after WW1. In Madagascar production decreased to less than 1 tonne in 1917 and did not pass that mark again until very recently – and then in a totally uncontrolled way (see table 1).
In the period between the two World Wars a number of medium or small mines in primary ore were developed in Madagascar, much as the Portuguese did in Mozambique or the Italians in Eritrea. But this sector in Madagascar never attained the vitality of, for instance, Northern Rhodesia (now Zimbabwe).
This could be due to fundamental geological reasons but other causes are also apparent. The miners seldom tried to extend exploitation below the oxidised, superficial zone. They were also poorly equipped with plants able to deal with sulphide ore with acceptable recovery. Their capacity to deal with water problems at depth was also limited. Actually, French underground mines of the past seldom went deeper than the water table, apparently regardless of the presence of further ore at depth.
Other causes, besides a constantly low gold price in the period, included the increasingly profitable graphite mines, the coffee plantations and a variety of new opportunities created by a very active French colonial administrations.
At independence in 1960 Madagascar’s gold production had trickled down to only few kilograms per year.
7.1.3 From 1960 to the present
In 1966 Mr H Besairie (1966,) ex-chief geologist of the Madagascar Geological Survey, reviewed and discussed the gold potential of Madagascar. This is the last organic study on the subject. Besairie estimated that between 1897 and 1959 the total production on the island had been around 51 t (or about 1,800,000 oz).
At the time gold prices were at an all-time low, and the Nixon administration’s decision to free up gold prices was still eight years away.
Madagascar’s official gold production (probably very close to the real one) languished to around 15-25 kg/year. It is difficult to say when the liberalisation of gold prices in 1971 seriously stimulated gold production in Madagascar anew, but this probably started in the early ’80s like the rest of the western world.
The U.S. Bureau of Mines (Antonides 1988) estimated that in the year 1987-1988 Malagasy gold production increased twenty fold. Probably by the year 1990 the Malagasy gold production, virtually all unofficial, had reached the present estimated levels of 3-4 t/y.
For its part, since 1972 the Madagascar Geological Survey began “Operation Or”, carrying out various surveys in the regions of Masokoamena (East Maevantanana), Tsinjoarivo (East Ambatolampy) and Dabolava (East Miandrizazo).
Region of Masokoamena: Prospecting of alluvial and eluvial occurrences of the lower valley of the Kamoro River. Installation and start-up of a plant exploiting the old alluvions of the Kamoro River. The exiguity of the reserves, the poor recovery and, presumably other inadequacies in planning, led to an early closure of the plant.
Region of Tsinjoarivo (Ambositra-Antanananrivo goldfield)
Prospecting of recent and old alluvions in the Onive River and its tributaries (sketch 7/8), about 50 km south of Antananarivo. Study done on the Onive River into a meander upstream of Tsinjorivo (sketch 7/8) in order to exploit the river bed in dry condition. This technique was used with some success at the beginning of the exploitation of the Itasy goldfield. However, the results obtained in the 1970s pointed to poor grades and reserves.
Some surface sampling of the primary deposits on the axis Sarobaratra-Andravoravo. This is an interesting theme and should be re-evaluated if the data is still available.
Region of Dabolava
Prospecting on the old alluvions of the Dabolava River (Betsiriri gold district) with negative results.
We note that all these activities were largely centred on old, well known goldfields and were targeting essentially alluvial deposits: hardly a priority target for foreign investors. Very little effort was devoted to original geological thinking and modern exploration aimed at the identification of large primary deposits.
Another period of official activity took place in the period 1980-1983 when a Soviet mission, assisted by personnel of the Geology and Mining Services (Service de la GŠologie, Service de Mines) carried out some prospecting work. The two targets selected were the alluvial deposits on the Maha River (West of Mananjary – see sketch 7/10) and on the primary deposit of Soavinarivo (East of Antisarabe on Ambositra-Antananarivo goldfield).
Primary occurrence of Soavinarino
By far the most interesting of the two targets, this exploration took place around the old working of Soavinarino. Prospecting was based essentially on geochemistry, panning concentrates and some geophysics.
These exploration activities were supplemented by a drilling program of six cored drill-holes down from the old working where spot values of 3-5 g/t Au had been found. However (by admission of the Malagasy authorities themselves) this drilling was very poorly carried out: four holes out of the six were vertical (on vertical formations!!!) and probably missed the target.
The core recovery was poor, particularly in the zones presumably mineralised. This seems consistent with Soviet exploration practices at the time. Also the idea of using surface geochemistry in an area contaminated by decades of working is highly questionable (IMR’s opinion).
This exploration program would therefore seem inconclusive.
Alluvions of the Maha River
The exploration took place essentially by geochemical means and panning concentrates over an area of 10 km2, followed by trenches and pits on the anomalous areas. Only a very modest potential of 330 kg Au has been suggested.
A more serious attempt to re-evaluate Madagascar’s gold potential was started by a program of French bilateral aid. The agreement signed in 1984 by a mixed French-Malagasy commission had as its objectives the “exploitation of the gold deposits of Madagascar”.
The field activities were carried out by the BRGM which has maintained for decades – and still does in 1996 – an office adjacent to the Geological Survey in Tananarive.
The objectives of this project were rather ambitious and intended to restudy, in a modern fashion, the gold potential of all Madagascar on a regional scale. By geological and metallogenetic means various priorities were selected for the 1984 field season:
Antsolobato (West of Antananrivo) Andravoravo (South West of Ambatolampy) Betsiaka (Andavakoera) Sketch 7/2, 7/4 Dabolava (East Miandrivazo) Itea (South West Ambositra) Sketch 7/8/1, 7/9
Further reconnaissances in a rubber dinghy took place on the rivers Ikopa (sketch 7/7), Onive (sketch 7/8) and Mahajilo to check the suitability of these rivers to a small type of suction dredge the BRGM was trying to market world wide (sketch 7/1/1).
There is no public record of the results of these works but we note that the BRGM activities sharply decreased after 1990, and there is not yet any organised or industrial gold exploitation in Madagascar in spite of the 3-4 t/y of gold produced by “artisanal” methods.
7.1.4 The “artisanal” sector
As in other countries of East Africa – notably Tanzania, Ethiopia and Eritrea – Madagascar has a thriving unofficial mining sector, locally called “orpillage” or “artisanal” mining. The workforce employed in this activity varies according to the seasons but it has been realistically estimated (Drean, 1994) at 150,000 to 200,000 individuals.
This rate of production of around 20 gr Au per man/year is consistent with other African countries with similar artisanal gold production. It is also consistent with logic. Madagascar’s GNP per individual is only $US230 per year, equal to about 18 gr of gold.
Also, Madagascar’s countryside is almost cashless, surviving largely by subsistence farming and barter. Most of the national income is generated and spent in the cities. The lure for a Malagasy farmer to earn a reasonable living panning what would be would be a negligible quantity of gold by western standards is simply irresistible.
Throughout history in the western world an ounce of gold was comparable to the wages of a skilled labourer over two weeks (Govett, 1982). In most of rural Madagascar an ounce of gold is equivalent to several months’ wages for a skilled worker – provided he can find work at all.
However, IMR disagree with some authors (such as Mutematsaka, 1995) about the sustainability of artisanal gold mining in Africa. The lesson learned from South America is that small-scale gold mining is inherently unsustainable. Brazilian gold production, where artisanal mining was the major source, has decreased from 101 t in 1989 to 75 t in 1994 and is still falling.
The idea of disciplining or controlling in any way this workforce is an illusion. It is impossible to put a policeman behind any gold miner. Beside the artisanal miners (“orpilleurs”), by virtue of their number, mobility and cash have traditionally enjoyed a political power way superior to their cashless peers in the countryside. Madagascar is no exception.
When, in the ’90s, gold was discovered at Rabeka, near Ambilobe -the birthplace of Madagascar’s president Prof. A. Zafy – the locality was immediately invaded by 15,000 unruly miners (Drean 1994).
The artisanal sector is important to Madagascar.
Several new areas are being worked (sketch 7/1) in regions well outside the historical goldfields, and this points to the “artisanal” gold sectors energetic, if primitive, prospecting activities. Some of these new gold prospects are in highly prospective geological settings.
Not all gold activities in Madagascar are uncontrolled. The Mines Service lists about 500 “Permissionaires” (Legal permit holders) and about 20 registered small gold mining companies (Personal communication by P.J. Rakotoarimanana Chief of the Service of Mining Inspection, Antananarivo, 1995).
The Malagasy government is trying very hard to control gold mining in Madagascar and several provisions of the new Mining Code of August 1990 (Law No 90-017) are aimed at Madagascar’s small gold miners.
Typical Malagasy gold mining practices
Some “artisanal” gold practices are unique to Madagascar and no ready English transalation is available. Here below are some common examples:
“Aloramo” (Malagasy word): the practice of skin diving in auriferous river to recover paydirt. This practice is particularly used in the Vohilava-Ampasary gold district.
“Lakantany” (Malagasy word): the practice of digging long derivation channels to collect gold from the hills (when auriferous) during the rainy season. This practice is particularly well suited to the denuded hilly morphology of Madagascar’s highlands. Several “lankantany” are clearly visible to this day from the highway between Antonanarivo and Antisarabe. At times the “lakantany” are supplemented with sluices (boites chinoises).
“Lavaka” (Malagasy word): Natural erosion gullies typical of Madagascar’s highlands. When cutting auriferous structures they are significantly enriched in gold.
Pillonage (French word): Crude crushing of ore by hand-held stamps, often truck half-axles. This method is rather effective in Madagascan conditions where labour is cheap and the primary gold mineralisation consists of free milling gold in quartz veins.
7.1.5. The Gold Trading Agency (Comptoir de l’Or)
In late 1994 the government decided to form a national Gold Trading Agency (Comptoir de l’Or) through which the Ministry of Energy and Mining would buy the output of private prospectors.
The Agency will deposit sale proceeds with the Central Bank. This is designed to boost official revenue at the expense of smuggling.
The full text of the project of Law on the Gold Trading Agency is given in Appendix 3 of this Database. The Decrete-Law is based on 48 articles and has been signed by the President of the Republic and six Ministers, including, significantly, the Minister of Police and the Minister of the Interior and Decentralisation.
It would be tedious and irrelevant to summarise the content of the 14 pages of this document. Suffice to say that the objectives of the Gold Trading Agency are (Article 1):
a) to buy the gold from licensed prospectors and authorised buyers on the field. Unlicensed prospectors or gold buyers become, by consequence, illegal;
b) to organise the sale, exportation or importation of all gold in Madagascar in case of necessity justified by the authorities.
On the field these measures will essentially be policed by newly-created Local Security Committees.
It is too early to see how these policies will work. IMR has been involved in similar schemes in Colombia, Zaire and Tanzania. Essentially the very small miner is persuaded to sell his gold production to a government agency only when the Government is prepared to pay a substantial premium on the prices paid by buyer-smugglers perpetually prowling about any artisanal goldfield (China is a notable exception).
This is tantamount to subsidising an unsustainable and environmentally unsound form of mining.
The Gold Trading Agency will be largely immaterial to any future large-scale miner as, obviously, the sale of any substantial gold production by a legitimate foreign investor could be negotiated directly with Madagascar’s central bank.
However, the Malagasy government would be well advised to use the inspectors of the Gold Trading Agency to restrict or prohibit two gold mining practices:
1) The use of hydraulic mining (prohibited in U.S. since 1884), a particularly dangerous practice in Madagascar’s predominantly agricultural society for the irreversible damage it cause to topsoil and,
2) The use of mercury for gold extraction. This mercury is almost never retorted and inevitably it accumulates in Madagascar’s delicate biosphere with deleterious and long-term effects. in 1989, gold-producing Ghana passed a “Mercury Law” (PNDCL217, see also Otto, 1995; p 445) in order to restrict or prohibit indiscriminate use of mercury.
7.2 MADAGASCAR’s GOLD DISTRICTS
To avoid arbitrary new groupings of Madagascar’s gold districts throughout the Database the classification proposed by the BRGM in 1985 has been maintained. This classification comprises 10 distinct goldfields which are described in sketch 7/2.
The relationship of these gold districts with geology and tectonics is given respectively in Plates 1 and 2 of this Database. Most of the descriptions of the individual deposits have, however, been taken from various works by Besairie (1964, 1966, 1969) and supplemented by a number of other publications.
7.2.1. Betsiaka District
Location and history
The district of Betsiaka (or Batsiaka-Andavakoera) is located in the extreme north of Madagascar about 80 km south of Antsiranana, (formerly Diego Suarez). See sketch 7/13 for location.
Access is easy: by plane to Antsiranana (daily flight by Air Madagascar, Boeing 737, see Appendix 4 for timetable) and then 131 km of surfaced road to Ambilobe. This town (comfortable hotel, telecommunications, airstrip) is central to the Andavakoera gold district.
The first gold occurrence in this district was discovered in 1906 by Mr Mortages near the village of Betsiaka (31 km east of Ambilobe by surfaced road). In 1909 production had already reached 1.223 t/y and was the most important for the island (see table 1a). Production decreased rapidly after the beginning of WWI and slipped below 100 kgs in 1917. The total recorded production of the Betsiaka gold district has been 1/4 million oz – undoubtedly much larger if we consider the “unofficial” production still taking place today.
The mineralisation consists of gold disseminated in veins of quartz and baryte (BRGM type c) near the contact between the Basement and the Paleo-Mesozoic sedimentary sequence of the Diego basin (see sketch 6/1).
The Basement consists of more or less migmatitic gneiss and micaschists in contact with a series of:
Permian clay-sandstones Triassic pelitic schists The Isalo continental sandstones.
This sedimentary series is cut by intrusions of microsyenites, essexites, labradorites and lamprophyres. The quartz-baryte veins occur into the Basement and the Permian formations but not the Triassic schists. Galena and sphalerite are common accessory minerals in the veins, probably representing a remobilisation of earlier mineralisations which Besairie (p 269a) estimated at 360 MA my.
The vein’s general strike is 50§ E. with several cross veins. The main vein system is generally parallel to the tectonic of the area, (sketch 7/4) and indeed of northern Madagascar. Hot springs (70§ C) are common in the area and their geochemical chracterisation would be unquestionably important (IMR’s opinion).
The gold veins have a thickness of some decimetres but occasionally can reach one or two metres and strike for several kilometres. The gold-bearing quartz-baryte veins occur over a length of about 130 km – from Anaborano to Ampisikinana – but they are heavily mineralised only in the region of Andavakoera over about a 20 km strike. Probably because the presence of galena, Andavakoera gold is always silver-bearing (electrum) with a finesse in the range of only 700-800.
Contrary to the majority of other Malagasy goldfields, Andavakoera’s gold production was essentially from primary sources. The mineralised quartz was extracted, crudely crushed and the gold recovered by panning.
Besairie (1966) indicates at least eight “important” underground mines in the Betsiaka gold district and they were (see sketch 7/4):
Only of five (*) have we some records: see sketches 7/5 and 7/6. From these it would seem that Betsiaka gold was mainly hosted in basement gneiss and extremely closed to contact with Permian sandstones. The underground works generally extended for only one of two levels 20-30 m apart, probably to the water table.
Andavakoera’s underground development was an impressive 17 km. From 1919 no rich gold zone was intersected and 1,440 m of underground development turned out to be totally unproductive. It was stopped in 1921 and the plant was closed in 1922 for lack of sufficient ore to be treated.
In 1934 an attempt to exploit (sluices) the Komakormalandy River alluvions was attempted but without success.
In 1950 the Malagasy Mining Department (French at the time) carried out a new study of the gold potential of the region but its results (probably thought to be negative) were not divulged. Immediately afterwards even the artisanal production ceased, not to be seriously restarted until the late 1970s.
No obvious attempt had been made to try to mine all the mineralised quartz, trying to exploit a lower ore grade with larger tonnage. This underlines an uncanny resemblance with what happened in the Western Australian goldfields at the beginning of the century, long before the gold boom of the ’80s showed that practically all the old “exhausted” mines could be worked economically at much lower grades than previously thought. It is suggested that the Betsiaka gold district should be re-evaluated with a similar approach (IMR’s opinion).
Table 6 lists 11 recorded deposits for the Betsiaka gold district, all of them hard-rock deposits.
The Ranomafana gold vein was exploited by a large trench and two main underground works to about 40 m in depth (sketch 7/5). The mine produced about 1/4 t of gold. The nearby vein of Ambilon produced about 400 kg of gold to a depth of 60 m.
In 1909 underground work began and a plant with a proper crusher was installed, but with disappointing results.
Apparently the mineralisation was very erratic and generally more consistent along strike rather than in depth. The exploitable zones are of rather limited dimensions but occasionally some can reach up to 200 m strike, with depth exceeding 60 m.
In the mineralised zones the gold grades are very irregular – from 0 to 300 g/t with an average of 20 g/t over a 1,000 t [recorded] production. In some smaller zones the grades have been extremely high: up to 150 kg for 10 t of quartz treated, or 500 oz/t.
The Ranomafana mine is the only one, for which records are available, that showed the depth of the mine seemed to been connected with the exhaustion of the high grade ore (and the contact gneiss/sandstones) rather than the meeting of the water table.
The Bereziky mine produced 800 kg of gold from a single pocket (pocket 1915, see sketch 7/6); this underlies the extremely erratic grades of thr Betsiaka gold district. Between these very rich pockets the grade varied between 0 and 3 g/t gold, at the time considered totally uneconomical.
The gold of Bereziky mine is entirely hosted in the Basement micaschists over a strike of approximately 500 m.
7.2.2 TSARATANANA DISTRICT
Location and history
The gold district of Tsaratan…na is one of the oldest known in Madagascar although its production statistics are often combined with the adjacent gold province on Maevatanana. The two provinces can be considered one.
Access can be by car to Antananarivo (a 6 hr drive) or more conveniently by plane to Mahajanga (direct flight from Antananarivo by Boeing 737, 7 days a week. See Appendix 4) and then by 153 km of surface road to Ambondronamany (modest accommodation, telecommunications, no licensed airstrip).
The Tsaratan…na gold district can be coveniently examined from here. A 4WD vehicle is recommended, particularly in the rainy season (November-April). Conversely a charter plane can be landed at Tsaratan…na township itself but no reliable vehicle hire or accommodation will be available there.
Gold in the Tsaratan…na district occurs essentially in quartz veinlets. Paragenesis is complex: tourmaline, barytine, pyrite, and silver, lead, bismuth, molybdenum, copper sulphides. These gold-bearing quartz veinlets occur within a variety of lithologies: migmatites, leptinites and above all gneiesses of the Archean Vohibory System, a Ca-Fe-Mg rich complex.
The Tsaratan…na goldfield seems to occur entirely within the Berofona Group (migmatites and anphibolites), with ages between 1750 and 1890 MA (Pb method). These formations have later been intruded by granite. Besairie (1964) indicates an age of 350 MA for these intrusions but this seems very debatable.
Other minerals occurring in the region are obviously pegmatitic ones such as beryl, columbite and quartz. Other mineralisations in the region are chromite, graphite and lead (economically exploited underground at Besaky, 16 55″ S -47 25″ E). A time correlation between the lead and gold mineralisation of the region is probable (IMR’s opinion).
According to the geological map N.4 of Madagascar (1:500,000 Service Geologique) more than 20 gold prospects occur within a 100 km radius from Tsaratan…na village. Some, surprisingly, are recorded over the sandstones of Isalo II sedimentary formations: these are, of course, alluvial deposits.
The gold-bearing veinlets of the primary occurrences strike N 45§ E and dip 35-60§ W. Their thickness varies between 15 and 90 cm, with grades between 2 and 11 g/t, but occasionally much higher: up to 10 oz/t at Ambatomisangana.
Table 6 lists 19 recorded deposits for the Tsaratanana gold district, most of them hard-rock deposits.
This is a small but very rich deposit located 4 km south of Tsaratan…na and 1 km east of Ambatomitsangana, on the right shore of the Mahajamba R. The mineralisation is in a very rich (several ounces/t of Au) of quartz and galena with gold. The vein was only 20 m long.
This deposit occurs 35 km south of Tsaratan…na. It has been prospected by the two small French companies “Syndacat Lyonnais” and “SociŠtŠ des Mines d’Ambatobe”. The mineralisation exists in a vein of quartz and baryte with pyrite, chalcopyrite, sphaelarite and occasionally bismuth and molybdenite. The presence of barytine is exceptional in a formation of Basement schists. The vein is concordant with the foliation of the intruded gneiss.
The main vein, interbedded with the gneiss and migmatites, strikes on 400 m with a width between 15 and 90 cm. The vein’s dip is between 35§ and 60§; no direction is given (Bes D, 271a) but it probably dips to the west.
There is a strong correlation between gold and sulphides. Grades vary between 2 and 11 g/t but it are much higher in the oxidation zone. This is, on average, 20 m deep. It is this zone that has been selectively exploited by French miners.
The mine was still active in 1939, particularly in its southern sector, with four levels developed on 90 m of galleries, adits and cross-cuts. These works met with a gold-bearing, quartz-sulphide lens developed over more than 300 m strike and plunging in several locations to 100 m below the outcrops. The vein’s thickness ranged between 20 and 60 cm.
Other works at 600 m to the north of the main mine, and particularly an adit of 112 m, have shown another vein with a thickness of about 60 cm. This and other mineralisations at 550 and 1950 m to the north graded 14.3 g/t Au with a total of 6,600 t of quartz crushed; but the recovery was probably poor.
In 1939 Mr Delaitre, a competent French engineer, advised works in order to establish the average grade. His calculations indicated that a production based on 15,000 t/y would be economic with gold grades of 7 g/t or above.
As was common for the period the working on Ambohipihaonana started on an abnormally rich oxidised zone. The mine had an independent hydroelectric power plant which operated crushers and mills (“bocards”). This plant was destroyed by a fire and the deposit was abandoned.
This deposit occur 40 km south of Tsaratan…na in a quartz-gold vein 0.25 to 0.40 m thick which has been followed to a depth of 40 m and along a strike of 250 m. Finely disseminated tourmaline and zircon are accessory minerals. The gold fineness is 858-900. Nearby a second quartz vein shows molybdenite and numerous inclusions of rutile and zircon.
The rich vein of Ambararatakely is located 30 km south-west of Tsaratan…na on a rolling slope below Mt Bejofo. The quartz-gold vein is rich in tourmaline and it has been exploited in the past, like other deposits of the region, by the Syndacat Lyonnais, mainly by monitoring away the gold-rich topsoil. The area is strongly lateritised, and some modern test work of these laterites would seem warranted (IMR’s opinion).
The deposits occurs 30 km south of Tsaratan…na in several quartz veins. The main orebody is a subvertical lens with thickness of 0.5 – 0.75 m. and striking at least 30 m. Among the accessory minerals there are actinolite-tremolite, chalcopyrite, azurite, pyrite, and native bismuth; the gold fineness ranges between 750-800, possibly indicating the presence of lead-silver sulphides (IMR’s opinion).
This prospect is in three quartz veins of which the most important, well interstratified in the schists, is about one metre thick. Chalcopyrite and baryte are accessory minerals. Apparently, only one vein has been exploited (Besairie, 1966, p272a).
This prospect occurs 30 km south-west of Tsaratan…na in close stockwork of small quartz veins only few centimetres thick. In some of them gold is directly visible to the naked eye. This mineralisation seems of the “dissemination” type.
7.2.3 MAEVATANANA GOLD DISTRICT
Location and history
The Maevatan…na gold district is immediately to the west of Tsaratanana. The town of Maevatan…na (comfortable hotel, telecommunications, no airport) is central to the goldfield and can be reached by 330 km of good, surfaced road from Antananarivo (sketch 7/14).
Maevatan…na was the goldfield where the first concession to foreigners was granted by the Malagasy government: to Mr Suberbie in 1886. The centre of these exploitations was at Suberbieville, which is now the town of Maevatan…na.
The first systematic exploration of Suberbie’s vast concession started in 1888 and was carried out by competent personnel including several mining engineers.
A dozen small mines were operative by 1891. The first hard rock mine started on a large concordant vein, with a thickness of 2.5 m with visible gold at Nandrojia, 1 km south of Maevatan…na. In 1891 a plant was installed with mill and amalgamation tables. Power was provided by two turbines of 80 CV on the Ikopa River (sketch 7/7).
In 1909 the Nandrojia vein was exploited by pits and cross-cuts but the operation was uneconomic and was abandoned. The alluvions and the eluvions were then providing the largest part of the production which reached 658 kgs (21,200 oz) in 1909. Gold production then decreased rapidly, particularly after the start of WWI.
Maevatan…na’s gold production was largely due to the efforts of Mr Suberbie and then by the “Compagnie Occidentale”, later to become the “Compagnie Franco-Malagache”. There is no record of the gold grades worked by these companies.
In 1914 attention was focused on the Ikopa black sands and the gold-bearing laterites. A small hydroelectric plant was built on the Antafofo waterfalls of the Ikopa (sketch 7/7) and a relative powerline. At least one work at Betaimby was equipped with monitors.
This large plant had only a limited life, and ended in total failure (Besairie, p 272b). Slightly later two dredges were brought on the Ikopa, one of them at Antafofo waterfalls (see sketch 7/7). Not surprisingly for the time, these dredges could not work properly as the Ikopa has very irregular bedrock. It would be interesting to see how modern small suction dredges, let’s say a Keene with between a 2″ and 6″ suction head, would preform today in the same region.
In 1921 rumours started about the extreme richness of the laterites of Tainangidina and of Ranomandry. A sober Mines Department Service downplayed expectations and carried out a survey, which although insufficient by modern standards, did not show serious resources (at the time; but in view of the successful lateritic gold deposit of Boddington in Western Australia a re-evaluation of Maevantanana laterites is well warranted – IMR’s opinion).
From 1929 the “Compagnie Franco-Malgache” devoted itself exclusively to the artisanal mining (orpaillage). Before WWII seasonal dams were built to dry various sections of the Ikopa over a length of 30 km which assured a good production. At least seven such barrages are recorded (sketch 7/7). These workings started anew in 1949 at Bekaprija but were again abandoned in 1951.
Maevatan…na goldfield is underlain by the systems of Graphite and Vohibory. The gold originates essentially from magnetiferous quartzites. The most productive district has been defined by the polygone between the Ikopa R. the Menavava R. and the Betsiboka R. (see sketch 7/7), or an area of about 7,500 km2, where at least 44 gold occurrences have been recorded (Besairie, 1966). In this area gold was exploited mainly in alluvions but also by crushing the exposed quartz veins at their contact with laterite.
Alluvial exploitations had been the most economic, but any attempt to mechanize them failed and only “artisanal” mining managed to survive.
In the case of the “black sands” the gold occurs as inclusions into the magnetite, showing the importance of magnetite-rich sandstones as the primary source of the alluvial deposits. As a consequence, the richest alluvial basins are the ones where the exposures on magnetite-rich sandstones are most abundant: the Ikopa Basin with its tributaries Nandrojia, Belambo, Mandraty, and Firingalava, and the basin of Kamoro with Tsiandrarafa, Aneriga and Bejofo.
The alluvial terraces, especially in the Ikopa basin, were never considered important as they had grades inadequate in relation with the thickness of the overburden. These terraces were seldom exploited, and then only by pits. A modern re-evaluation taking in account present economic ore grades and modern, low-cost stripping techniques coupled with efficient magnetic separation, seems warranted for the Maevatan…na gold district. (IMR’s opinion)
We note that Maevatanana is one of the districts where amalgamation was most extensivily used; most probably without any retorting and recovering of the mercury. A study of the present environmental conditions of the district would seem highly desirable.
Table 6 lists no less than 43 recorded deposits for the Maevatanana gold district, most of them alluvial.
Below are listed some of the more interesting gold occurrences of the district.
This prospect occurs 50 km south of Maevatan…na and 2 km east of the Ikopa River. It is a very old prospect, exploited since 1888, and which consists of numerous veinlets of gold-bearing quartz distributed in small pockets along the same plan (“en chapelet”) in the lateritised gneiss.
Starting in 1914 these laterites were worked by monitors and sluices. Gold was recovered by amalgamation. A hydroelectric plant was installed at Antafofo on the Ikopa River utilising a fall of 17 m and generating 200 CV and a 7 km powerline to join it to Betaimby. The failure of this venture has been total: 20,000 m3 of laterite produced only 1,146 gr Au, or a grade of 0.06 gr/m3. Available records do not mention which type of plant was used nor what gold recovery has been achieved.
Only 1 km south of Maevatan…na, this prospect was the first hard-rock exploitation by Mr Suberbie. A conformable quartz vein 2.5 metres thick was worked at the surface over 40 m and then exploited underground in pits and cross-cuts. The quartz was milled. These works became uneconomic in 1910 and were stopped the same year.
In the Ranomandry sector, 30 km south of Maevatan…na, several gold prospects occur between the villages of Bejofo and Betanimanga. It has been suggested that these prospects consist in a single, continuous vein; this is debatable.
There was a reconnaissance in 1928 over the old superficial works of Betanimanga. The 73 samples collected gave an average grade of 18.6 g/t Au. An amalgamation test over two tonnes of quartz has given a grade of 29.4 g/t Au. In 1928 the underground workings consisted of: an incline of 34 m, a cross-cut of 80 m and two galleries of 50 m. These workings have not been followed.
Much has been said about this deposit, situated 25 km south-east of Maevatan…na (sketch 7/7), both for its vein and laterite potential.
The first study was carried out in 1915; others in 1923 and 1927. The deposit occurs in gently rolling hills and consists of eight gold-bearing quartz veins concordant with the gneiss of the Vohibory system. The eight veins cover a width of 200 m. A ninth vein is about 100 m away from the main system. The average thickness of the veins is 30 cm and their length is between 50 and 150 m with the exception of one that strikes 650 m.
The average ore grade worked was around 18 g/t Au. All these veins, dipping 60§, are apparently exploitable to a depth 100-200 m and one of them to 300 m, but this figure seems implausible (IMR’s opinion). A cross-cut 320 m long intersects the vein swarm. On this basis a tonnage of 200,000 tonnes of quartz would be equivalent to almost 4 tonnes of gold (Besairie, 1966 p273b).
However, these calculations result from rather risky extrapolations without systematic sampling and no proof that the ore grades extend at depth. In other words, the prospect has been considered a proper single vein deposit rather than a system of veins with large variation in grades and continuity.
Resource estimates of the Tainangidina hill’s laterites appear to be limited, contrary to previous hopes. Also, the grades are rather low with the exception of the vicinity of the gold-bearing quartz veins. All organised work on Tainangidina stopped in 1928.
The Ikopa river bed is unquestionably gold-rich but its exploitation is difficult. The river is deep and the current strong. The river bed is irregular with boulders, channels and scours. An attempt with two dredges in 1917 ended up in failure. Particularly galling was the fact that the rainy season invariably destroyed the river dams and that work was possible only in the dry season.
Between 1930 and 1944 certain sectors of the Ikopa, Mandarti and Belambo rivers were dried by means of dams and derivation channels. This technique permitted the exploitation of the dried sectors for 2-3 months a year. The same barrages were built anew after one or two years and they provided about 50 kg/year of gold. Sketch 7/7 shows some of the largest dams built on the Ikopa.
The last effort on the Ikopa River was made at Bekapirijy where a small rocky island favoured the construction of a dam. This was followed by digging, on the western shore, a long derivation channel and the exposure of the river-bed for a significant distance. This project, possibly the largest ever established on the Ikopa River, worked intermittently between 1949 and 1951 with a meagre recorded production of 7.1 kg of gold. No further barrages have been built on the Ikopa although some other attempts have been made with suction dredges in recent times.
7.2.4 BETSIRIRY GOLD DISTRICT
Location and History
The Betsiriry gold district is located to the extreme west of Madagascar’s crystalline Basement (sketch 7/14) between 19§ and 20§ latitude south and 45§ to 30′ longitude.
The town of Miandrivazo (airport, telecommunications, small hotel) can be reached by 250 km of good, surfaced road from Antsirabe or directly by plane from Antananarivo (sketch 7/14).
This gold district produced 2.5 t (80,000 oz) of gold between 1901 and 1921. The greater production took place between 1903-1914 with a peak production of 205 kg of gold in 1910.
As usual, attempts to dredge the major rivers of the district ended in failure. In particular, an English company built a plant which collapsed before reaching the Mahajilo Falls where it was supposed to operate.
The BRGM indicates this goldfield as being Proterozoic in age and so as not to complicate the issue this has been maintained in sketch 7/2 of the present report.
In reality this assumption does not seem adequately supported. Besairie (1964, Feuille du Centre) put these gold mineralisations firmly in the Amborompotsy Group of the Vohibory system. Hottin (1972) proposes an age between 1,700 and 2,000 MA for these lithologies. On the basis of available information the Betsitiry gold district does not look significantly different to the great majority of the Madagascar’s other gold mineralisations which are considered of Archean age.
The only distinctive character of the Betsiriry gold district is that the known gold mineralisations appear to be located in the “migmatitic front” or in the passage zone between the gneiss and the epimetamorphic series “schist-quartz-limestone”.
In a radius of 50 km from Miandrivazo at least 14 gold occurrences are reported (Besairie, 1969, Feuille 5). These prospects occur in gneiss and migmatites and they appear unrelated to later intrusions.
The mineralisation is in free milling quartz often associated with magnetite and iron and copper sulphides. In some deposits (Ankaboka) part of the gold is syncrystallized with the magnetite. In others (Antasaily) gold is associated with mispickel.
The Betsiriry gold district may be considerably larger than indicated in past reports. We note several gold prospects: Ankofoka, Antsiroroka, Antsevakely, Miandrarivo, almost 100 km north-east of Miandrivazo district in what is essentially the same geological environment.
There is evidence that recent prospecting by “artisanal” miners has further extended the boundaries of the Betsiriry gold district (sketch 7/1).
Table 6 lists only eight recorded deposits for the area is still little known. Significantly, all of them are primary.
Individual gold deposits
Among the most important deposits of the Betsiriry goldfield is the Dabolova Group, 30 km southeast of Miandrizazo, which has been in continual exploitation from 1885 to at least 1966 (Besairie, 1966).
The quartz vein of Takodara I striking 2 km has been exploited over all its length. The recorded grade varied between 10 and 50 gr/t Au. At Ambohipisaka, there are there are four main veins, very irregular and in separate, lens-shaped gold-quartz occurrences (“en chapelet”).
An exploitation of Dabolova was attempted between 1937 and 1939 with crushers, mills and amalgamation tables. In 1938, 200 t of quartz yielded 2.8 kg of gold indicating a minimum grade of about 14 g/t Au. We note that the plant was not equipped for the treatment of auriferous pyrites. This may account for the low gold recovery (IMR’s opinion).
Other prospects of Betsiriry goldfield still artisanally worked in 1966 were Analabe, Ankarongana, Kiranomena, Antasaily and Andisiavo.
7.2.5. ITASY GOLD DISTRICT
Location and History
The gold district of Itasy-Tsiroanomandidy is located 50-150 km west of the capital, Antananarivo, and produced 1,260 kg of gold between 1901 and 1921. Numerous vein deposits were worked and rapidly abandoned. Its peak production was in 1904 with 174 kg produced, largely from the Vohinambo deposit.
The Itasy gold district is a rather diffuse one, without a distinct geographical expression. The village of Analavory (telecommunications, small hotel, emergency landing strip) can be reached from Antananarivo by 124 km of good surfaced road (sketch 7/13). From this village most of the gold prospects of the Itasy can be visited. The use of a 4WD vehicle is advisable.
There is relatively little geological information on the Itasy gold district and practically no deposits marked even on the 1:500,000 geological maps. The district can be seen as the western extension of the Ambositra-Antananarivo gold district.
The gold occurrences occur in the migmatites, gneiss (often garnet and sillimanite bearing), quartzites and micaschists. All the gold prospects occur in the graphite-rich zones of the Archean Graphite System. Granitic intrusions are frequent in the region but are unfortunately undated. Some gold deposits seem controlled by the strong N-S and E-W tectonics of the area (see Plate 2 in the present Database).
The quaternary basalts that form the Itasy massif itself are unrelated to the gold mineralisations.
Throughout the district there are several mentions of auriferous quartzites with magnetite: i.e. Ambohimanoa, Ambohitsivalana, Behana. These are potentially large if low-grade deposits very amenable to modern extraction techniques, particularly if the gold occurs (as has been indicated) as inclusions in the magnetite. IMR is of the opinion that this is well worth investigating.
Besairie (1966) lists 13 gold deposits occurring in a large arc between Ambatolampy and the Itasy (see also Table 6); all primary. These deposits are described below:
The prospect is located at only 9 km to the south of Tananarive. It is a very old prospect in several small veins of gold-bearing quartz in migmatites, gneiss and granites. The prospect has been worked by a large trench producing between 1-2 kg gold per year.
This deposit is located 10 km south-west of Arivonimamo. The deposit was discovered by Mr Talbot in 1904 who extracted 70 kg of gold in a few months. Once again the deposit consisted in series of gold-bearing quartz veinlets of modest thickness interstratified into the gneiss. The mineralisation is enriched at the contact with the overlying laterites. The occurrence has been exploited on a trench of 80 m strike and 25 m depth and then by underground works. These works, poorly executed, caved in and the deposit was abandoned.
20 km north-west of Tananarivo this deposit consists of a large quartzite lens in sillimanite-rich lithologies. No quartz-gold vein as such has been recognised. Basairie considers this mineralisation of a “disseminated” type; it certainly looks anomalous compared to the prevalent style of gold deposits in Madagascar.
A sampling program, presumably carried out in the 1960s on the old working and consisting of 60 m of channel sampling, produced five samples out of eight with grades between 1,5-2 g/t (by amalgamation). The crushing of the other samples to 100 mesh did not indicate gold. Along the hillsides quartzites have long been worked in the past by long hand-dug channels (“lakantany” in Malagasy) which drained auriferous eluvions during the rainy season. On the hillside there is an alluvial terrace which, in the past, has been exploited in its richest parts.
It is obvious that Ambohimanoa has been worked only with very crude artisanal methods; given the mentioned “disseminated” nature of gold deposits in sedimentary formations a modern quantification of the Ambohinamonoa prospect is well warranted (IMR’s opinion).
This prospect occurs 20 km south of Arivonimamo village. Its old working date is around 1912. A gully-dissected hill is the likely source of the gold in the Antosalobato creek. A bed of mica-gneiss about 15 m thick hosts abundant quartz-gold veinlets concordant with the gneiss foliation and dipping 60 degrees N. The largest vein, about 1.2 m thick, showed visible gold over 10-15 cm. Pyrite is also present. Underground works have failed to find extensions of this deposit.
This prospect occurs 50 km to the west of the Tsironomandidy village. Its placers were recognised at the start of the century. Two hills, Ankafotra and, above all, Betanimena, show a substratum of auriferous gneiss. Where these have been lateritised they formed local concentrations of very fine gold, with occasional outcrops of auriferous quartz veinlets. In the alluvions of the Ankafotra and Bekopaka rivers gold can occur as pepites (suggesting a goldfield where gold detectors could be usefully employed by individual miners). The forested areas of these alluvions have not been worked.
This prospect, located 40 km south-south-east of Tananarive, consists of altered and lateritised gneiss with veinlets of auriferous quartz. The occurrence has been prospected over a 2 km strike with trenches of various depth. These works are very old and probably date to the end of the last century. Underground works were carried out in 1910-12; there is no record of the results.
A prospect 35 km to the east of Tsiroanomandidy village. The placers were recognised at the beginning of this century. Some early exploitation produced about 50 kg Au before 1895. Two quartz veins 40-80 cm thick strike over 200 m and have been literally riddled with shafts of 12-15 m depth.
The quartz was artisanally crushed (“pillonn‚”) and washed. The auriferous veins seem to disappear immediately outside the worked zone. Underground works have not been successful. Nearby there is quartzite with weakly auriferous magnetite which has formed low-grade alluvial deposits. Gold recovery has been attempted with shaking tables. No mention of modern exploitation by wet magnetic separator (IMR’s observation).
A prospect 65 km east of Tsiroanomandidy. There is an old alluvial exploitation in a zone with magnetiferous quartzite and amphibolites.
This prospect lies 52 km to the north-west of Tsiroanomandidy village and was exploited even before 1895. Two placers of 1,800 x 800 m and 1,500 x 100 m produced 387 kg of gold between 1903 and 1909. Production then fell rapidly. The prospect occurs around the Betanimena hill which consists of amphibolites, gneiss, micaschist and, once again, magnetiferous quartzite.
The amphibolites, largely formed by the cummingtonite-grunerite series, enclose a layer of kyanite (disthene) with visible gold. The magnetiferous quartzites are auriferous and at times show visible gold. Both eluvions and alluvions have been long exploited. Some essays by sluice between 1909 and 1910 have been rather unsatisfactory with yields of about 1 kg Au a month. The exploitation mainly took place by the Malagasy method of “lakantay”.
7.2.6. AMBOSITRA-ANTANANARIVO GOLD DISTRICT
Location and history
The Ambositra-Antananarivo gold district is particularly developed in the province of Antsirabe and officially produced 1,489 kg (48,000 oz.) between 1901 and 1921. The largest part of this production came from the region south of the Onive River (sketch 7/8). Some deposits occurred around Ambatolampy and in the Faratsilho sector.
Gold production was particularly important from 1890, when the exploitation was carried out by administrative corve‚s. Around 1900 these corve‚s employed more than 2,000 workers in the Sarobaratra River alone. The inevitable exhaustion of the alluvial resources took place immediately afterwards and was a powerful incentive to the first exploitation of primary gold, particularly where their contacts with the overlying laterites formed zones of strong enrichment.
This gave the district a new lease of life with a high production between 1904 and 1911. At that time numerous exploitation of graphite were developed and attracted labour away from the less lucrative gold workings. Production has been totally artisanal ever since.
It would be futile to list all the deposits that occur in the Ambositra-Antananarivo goldfield. In any case records are very scarce, and they are mainly known by traces on ancient workings (Besairie, 1966, p 276).
The heart of this goldfield can easily be reached by 100-180 km of excellent surfaced road from Tananarive (sketch 7/15); most individual deposits can be reached only by 4WD vehicles, particularly during the rainy season. The town of Antsirabe offers very good and pleasant accommodation.
Once again the gold mineralisation of Ambositra-Antananarivo is hosted in migmatites, gneiss and micaschists of the Ambatolampy group, Graphite System (see Plate 1), containing quartz-gold veinlets with secondary alluvions and eluvions.
The largest part of these deposits is within the zones of micaschists or micaschist-gneiss but they appear little affected by the migmatisation. On a regional scale gold seems to be distributed on the migmatisation front.
Leucogranitic intrusions are common in the area but their relationship to the gold mineralisation, if any, is unknown.
The regional tectonic is essentially N-S and E-W and some deposits appear fault controlled.
Sketch 7/8 shows some of the most notable workings of the south Onive district over an area of approximately 700 km2. Besairie (1966) mentions at least five underground workings (Analasarotra, Andranofito I and II, Ankanona, Miakatso), but there have certainly been many more.
The primary deposits of Andranofito, Tongarivo and Soavinarivo consist of concordant quartz veins, locally rich and rapidly lost at depth where they reportedly had uneconomic grades (but at the time, grades below 10 g/t in hard rock were considered uneconomic). Below are given some details of the last deposits to be worked in the region.
Table 6 lists 39 recorded deposits for the Ambositra-Antananarivo gold district. About half of them are primary.
Individual deposits (Antisarabe region)
Gold was exploited on the Onive River in the dry season, in particular downstream of the Tsinjoarivo. Some projects, utilising sand-pumps, had been planned but were never carried out. An attempt to dredge downstream of Antanifotsy failed.
The mount Sarobatra (1,867 m a.s.l.) is the highest point of a topographic range 25 km long which terminates at the Onive River, north west of Tsinjoarivo village (Sketch 7/8). The gold workings, very old, were developed on the Sarobatra River and its tributaries: the creeks Analava and Anteritery. The alluvions were very well developed with thicknesses of between 2 and 4 metres.
The grade was initially rather high, reaching 4 – 5 gr/m3. These alluvions extended about 200 m. The entire length of the wide valley of Sarobatra has been worked. It was the best alluvial deposit in the region.
The latest alluvial exploitations were developed on Miakatso and Besorohitra creeks to the east of Antofimbato; Ambodiala, Laptsihazo, Antanetibe and Saovinandriana to the east of the range; the creeks Analalava and Anterivody to the south-west and Antasahondra to the south. The last works took place at Ambohimanga (1,500 m north-east of Sarobatra) and Antanetibe (3 km to the south-east). In 1969 there still was production from Antsofimbato, described below.
This prospect lies on the north-east extension of Sarobatra; the old workings of Antsofimbato in the 1950s attracted attention because the continuity of its production: more than 1 kg gold a year. Here is the synopsis by Besairie (1966, p 276b) of some investigation carried out in 1961:
“The formation worked consists of a bed of heavily lateritised micaschists, about 20m thick, resting with a dip of 45§ over the quartzite which is the backbone of the mountain range. These micaschists enclose several concordant quartz veinlets striking about 100 m and mineralised over a thickness of 50 cm.
These veinlets are not continuous but rather in separate little lens-like pockets (‘en chapelet’= rosary-like) over a width of about 10 m in the micaschists. Gold is sometime visible to the naked eye but more often is only visible after crushing and washing the quartz.
The micaschists contain traces of gold, very fine and very dispersed, with no [apparent] economic grades. The rich zone has been exploited by trenches and some minor underground working. A 1960s study by BRGM concluded that the grades were insufficient for mechanised exploitation of the deposit.”
This abandoned gold prospect is located 30 km south-east of Ambatolampy in a series of graphitic micashists. The prospect was examined in the 1960s by BRGM personnel (Besairie, 1966, p 277a).
The principal bed, exploited over 1 km, consists of a level of micaschists very rich in sillimanite (local name = vatodidy) with an average thickness of 50 cm, intercalated between quartzites on the footwall and a graphite-bearing layer on the hanging wall.
The deposit has been entirely exploited in its eluvial and alluvial parts and also in the sillimanite-rich part more readily accessible by trenches. Channel samples in the sillimanite-rich part of this prospect have indicated gold grades from 1 to 5 gr/t. We ignore the analytical techniques for these determinations: probably nothing more that hand-crushing the quartz followed by washing it with a gold-pan (IMR’s opinion).
This gold prospect occurs 24 km west and slightly south of Tsinjoarivo. Its exploitation started in 1889 by Mr Savaron – then one of the first legal French exploitations in Madagascar.
All the creeks running from the hills were more or less auriferous. To its south-west the deposit was worked at the beginning of the century by Anasaha. Thick, bluish, quartz veins concordant with the mica schists’ foliation were the gold source: the gold generally being present in association with pyrite. Unfortunately these veins were very discontinuous. The Belanitra, Antkitsika and the Andranomiady rivers have been worked for alluvial gold.
This gold prospect occurs 9 km south of the Ambatomiady village and it is important both for its alluvions and its underground workings – at least two of them (see sketch 7/8). Once again the gold occurs in numerous quartz veins in the micaschists. The most important workings are around the topographic peak of Andranofito with over 379 m of underground working. But the main vein, with visible gold, was worked in a very rudimentary way, with crowbars.
A prospect 31 km ESE of Antisarabe. This deposit was the first to be worked underground in the region. The prospect consists of a vein of gold-bearing pyritic quartz which has been exploited by superficial workings over a length of 300 m.
A 25 m shaft was sunk to exploit the prospect at depth but was abandoned because of water difficulties. The workings were abandoned in 1911. There are no records about ore grades. As the ore was very rich in pyrite, a small plant for the crushing and washing of the pyrites was installed. After the first recovery of the gold by panning, the residual pyrite was chemically treated by the Chemical Laboratory of [Antananarivo’s] Mines Service.
A gold prospect 12 km east of Antisarabe. Three quartz veins were worked both om the surface and underground. Once again, all activities ceased in 1911.
A gold prospect about 20 km north-east of Faratsiho. There are important underground works in the sectors of Faravoitra and above all at Antanifotsy. The gold is found as inclusions in the gneiss and these have been exploited particularly along alteration [lateratization] zones. But the main production came from alluvial deposits.
A gold prospect 45 km WSW of Antisirabe, on the upper course of the Isakelo River: a tributary of the Mania River. The ancient workings extended over several km in the valley. A quartz vein with visible gold has been totally mined out.
Individual deposits (Ambositra region)
A gold prospect 18 km south of Ambositra in the upper valley of the Ivato River, the prospect showing important old workings. Two large trenches, one 400 m in length (probably visible in Satellite images – note of IMR) were made to exploit an auriferous level, now partially covered by slides, in the migmatites: probably the gold mineralisation was hosted in quartz veinlets as this is the regional pattern. This occurrence has given place to important eluvial deposits and to a mineralised [fluvial] terrace now totally exploited.
Itea is a rather different deposit from most of the region. It occurs 50 km to the south-east of Ambositra (sketch 7/8/1). Its position is well to the west of the main Ambositra-Antananarivo goldfield. Also, while the majority of the gold occurrences of this goldfield are in the micaschists and the graphitic gneiss of the Ambatolampy Group of the “Graphite System”, Itea gold prospect is apparently hosted in the granite of Vavavato-Antofinandrahana which Besairie (1964) estimates to be 700-1100 MA in age.
The Itea area is heavily mineralised with copper, lead and bastnaesite. Pegmatites are also frequent in the area (quartz, beryl) and a few have been mined (i.e. Tambolehibe). The strike of the pegmatites and some major faults in the region is N 40§E. It would seem that this fault has at least partially controlled the Itea prospect.
The mineralisation apparently consists of gold impregnations into the micaschist and the quartzite but also some alluvions. Itea’s primary mineralisation was about 7 m thick and has been worked underground, probably not below the water table, at about 22 m from the surface.
BRGM investigated Itea in the 1960s but the works were not apparently followed up and very little is presently known of this prospect beside the poorly-drawn section given in sketch 7/9.
Given the anomalous nature of Itea’s mineralisation a detailed and modern investigation of this deposit seems well warranted.
7.2.7. VOHILAVA-AMPASARY GOLD FIELD (MANANJARY)
Location and History
This goldfield is often referred to in literature (ie. Besairie, 1966) as the Mananjary goldfield. It has been one of the major producers in Madagascar with a recorded production of 8,580 t (276,800 oz) of gold between 1901 and 1921: an impressive performance.
There are no records of this goldfield producing before 1901 but at that date it was producing in excess of 500 kg/y (16,100 oz) or about half of all Malagasy production at the time. Misguided French investors and administrators (Gallieni, 1990) were at the time pinpointing this goldfield as a potential rival of Witwatersrand in Transvaal. An entirely different geology of the two goldfields rapidly disproved these wild expectations.
The gold exploitation of this goldfield was particularly intense until World War I with a peak of 744 kg/y of gold in 1903. It decreased sharply immediately after, particularly when coffee plantations over the old gold alluvions proved more economic that artisanal mining.
The goldfield occurs around the pleasant coastal city of Mananjary, 350 km south of the main port of Toamasina (ex Tamatave) on the Madagascar east coast – see sketch 7/15. Mananjary (telecommunications, airport, hotel) can be conveniently reached from Antananarivo by commercial flights with Air Madagascar’s “twin otter” planes.
The Vohilava-Ampasary gold district is underlined by the gneiss and migmatites of the Mananjary Group of the Vohibory system (Besairie 1964) and dated at 2,150 MA (Pb/Pb method). This group is equivalent to the Ambatolampy Group in central Madagascar. Intrusive in the Mananjary migmatites is the biotitic-monzonitic granite of Befody (see sketch 7/10).
In this region of Madagascar the Vohibory system is rather different from the rest of the island. It can be split up into three sections: the Maha group in the east (sericite and chlorite-rich schistes affected by a tectonic zones with tight folds, faults and mylonite zones), the Vohilava group in the centre (mica-schists and geisses), and to the the west the Ifinadiana group (closely-folded migmatites). Throughout the region there are numerous, small intrusions of ultramafics.
The impression that at least some of the Vohilava-Ampasary gold occurrences can be hosted in what an Anglo-Saxon geologist would call greenstone belts cannot be be dismissed. Hottin (1972) seems to suggest this possibility.
Geochronological determinations have given an age of 2,140 MA for gold-sulphide mineralisations (Andrambo) and two possibilities close to 900 MA for a second mineralisation cycle: 890 MA for the zircons of the Namolika granite to the extreme south of Befody massif (Pb/Pb), and 850 MA for the alluvial monazite of Mananjary (Pb/Pb) (Besairie, 1966).
It would therefore seem that an age of around 850 MA can be safely suggested for the Befody granite: this is in good accord with the general period of granitisation and charnockitisation of Madagascar and peninsular India (See Plate 1 and sketch 6/3).
Sketch 7/10 shows the distribution of the known gold deposits of the Vohilava-Ampasary district. We note to the west of Befody granite the auriferous zone Ampasary-Sakaleona, and to the east the zone “de la Petite Falaise”, and still further east the region Saka-Maha-Sahandrambo – essentially alluvial.
The primary gold mineralisations are geologically controlled: they are all below the magmatitic front. In Ampasary-Sakaleona region the gold mineralisation is localised in quartz veins at the contact between gneiss and the lenses of ultrabasics included in the gneiss. On the “Petite Falaise”, the gold occurrences are localised at the contact between granite and crystalline schists. The auriferous quartz veins occur in both lithologies but generally at less than 100 m from the contact. Significantly, all the creeks running across this contact are more or less auriferous.
In the case of the Maha and Sahandrambo rivers the gold deposits are over large fault zones and it is plausible that there is a correlation between these fault zones and gold mineralisations, both primary and secondary. Some primary gold deposits occur as far as 30 km away from the known surface expression of the Befody granite (sketch 7/10).
One of the characteristics of the region is the abundance of quartz and sulphide veins. Their thickness varies from 0.2 to 1 m, and it is generally largest in the faulted zones. The mineralisation consists of gold, pyrite and mispickel [arsenopyrite] commons.
Chalcopyrite and galena are rare and in variable proportions. Tourmaline and muscovite are common. Some pegmatites are gold-bearing although this can probably be dismissed as an unimportant remobilisation episode during the Pan-African event (480-550 MA. A major proportion of the gold occurs as inclusion in sulphides.
From about 100 samples collected in a study carried out in 1952, all proved to be auriferous but with grades at or below 0.5 g/t Au (Besairie, 1966); but the gold seems to be ubiquitous.
The regional morphology is important in the control of the placers. In the sharply cut valley the rivers tend to have a torrential regimen. The alluvions are therefore very irregular and the gold distribution is controlled mostly by the bedrock’s shape and nature.
The evolution of the relief has given place to several ancient terraces, the oldest only 20 m below the thalwegs. The surface of the alluvions is, in the majority of cases, smaller than 10 hectares and it reaches 50 hectares in very few cases. Larger deposits do exist along the Saka and Maha rivers but their exploitation proved to be difficult.
In the region there is a secondary hydrographic network formed by small water courses of modest importance but with frequent alluvial terraces. The placers of these tributary rivers have been practically exhausted. The placers of the main river system have been exploited wherever accessible by a shovel. The old river terraces, more or less at water table height during the dry season, are covered by fine alluvions 5-8 m thick. These terraces have rarely been exploited. Furthermore, they are now overgrown by coffee plantations.
In most of the auriferous alluvions of the Vohilava-Ampasary goldfield the gold-bearing pebble horizon is covered by 3-5 m of fine alluvions and lateritic clays. But, in spite of this, overburden exploitation is easy if water is readily available. Most of the richest terraces have already been exploited.
The grades in the alluvions range from 1 to 2 g/m3 but exceptionally can reach 3 – 4 g/m3. The thickness of the auriferous conglomerate varies between 0.5 and 2 m. The average grade for the terraces still unexploited (1966) is around 1 g/m3 or less.
The gold recovered is generally coarse. Pepites are rare and of small dimensions. The gold fineness never goes below 945 and occasionally reaches 995.
In the following chapter we will describe several gold deposits, mostly, but not all, from Besairie (1966). Only a few of these deposits have been studied in any detail. It is these mineralisations that – regardless of their grades – fed the secondary deposits, either alluvial or eluvial, and these have produced most of the gold in the region.
Table 6 lists a record number of 58 known deposits for the Vohilava-Ampasary gold district. Significantly, 27 of them are primary.
The small area of the Ampasary River (see sketches 7/10 and 7/11), 70 km north-west of Mananjary, is the second biggest gold producing area in Madagascar, immediately after the Andavakoera. The Ampasary course is sinuous and interrupted by numerous rapids. Important auriferous terraces are developed around it in major meanders (sketch 7/12). On the east of the river, on the hilly slopes, several prospections for hard-rock gold have been carried out with success. But obviously this has been an under-explored target.
The richest zone starts to the south with the placers of Hanning and Betampona which have produced respectively 119 and 132 kg of gold. More to the north Malazamasina and Alexander have produced respectively 55 and 195 kg of gold: some terraces and flats in this area have not been exploited due to heavy forestation.
Further north there are the placers of Antanbao which have produced 367 kg of gold: this section of the river consists of a succession of rapids and deep pans where the exploitation was carried out by diving (“alorano”, in local parlance). A series of alluvial terraces occur on both sides of the river: the richest have already been exploited.
Given the chaotic way of the old workings is difficult to estimate how much gold could still be won from the Ampasary River but several meanders are certainly still very rich. The Ampasary River ends with the sectors of d’Ambalavia and Ambodiara which produced 125 kg of gold. The auriferous zone extends to the north with the basins of the Sakaelona.
Several primary gold deposits are known on the eastern shore of the Ampasary. They have been exploited only by very primitive means, without the use of compressors or explosives and they have been quickly abandoned at the first difficulty. Among these primary deposits we can quote Ambalakaza-north, Tobilava, Antanasy and Antanambao-east and Ambalavia-Ambatomainty.
All these works were in gold and sulphide-bearing quartz veins in amphibolite and tremolite schists. It would be interesting but probably near impossible to locate these old workings after more than 80 years. The region and the style of mineralisation is rather favourable to regional exploration by modern geochemistry: initially by stream sampling followed by grid soil sampling on anomalous zones (IMR’s opinion).
The Sakaleona River and its tributaries (Sahanana, Andranomanjaka, Tsaravinany, Nandravaona, Tembinah and Sahakoriana (Besairie, 1966 p 279b) have yielded more than 500 kg of gold. See sketch 7/10 for a general view of the area. Obviously, the geological setting is very similar to the Ampasary goldfield and all gold mineralisations originate from the contact between the Befody granite and the enclosing gneiss and micaschists.
La Petite Falaise
This series of deposits occurs along the eastern contact of Befody granite. Some individual deposits are described below.
At Bebasy, 12 km south of Soavina village, a vein in the sericite-schists has been exploited at the surface over 520 m, and underground for 350 m. The quartz was crushed by a battery with 10 stamps powered by a steam engine. The average ore grade was a respectable 13.5 g/t Au with a gold finesse of 970.
Six km to the south the vein of Sahafandroana, another quartz vein, yielded gold grades superior to Babasy but it was worked very little and prospected only by a trench of about 100 m in length. In the same sector to the west of the Ambodilafa village there are other primary exploitations: Ambavalero and Ambohitsara. The same sector also hosts several auriferous alluvions, particularly along the tributaries of Sahavato: Sahafandroana, Sakandrekata, Sakafotsy Sahafanana and Ankelakambo.
Perhaps the most important primary gold deposit of the region is Andrambo-Maroantovo, 40 km to the SSW of Soavina village. The deposit consists, as usual, of a lens-like quartz veins concordant with the Mananjary gneiss. These gneiss are often dioritic and have lenses of soapstone.
The deposit is well within the surface expression of the Befody granite (sketch 7/10). Galena from this vein has been dated at 2,140 MA. The main vein strikes N 140§ and dips 70§ to 80§ with an average thickness of only 20 cm; this vein has been followed on strike for about 4 km by artisanal miners who have exploited only the richest sectors, with reported grades of 30-80 g/t Au and even higher (Besairie, 1966, p 280b).
The southern sector of the vein is the better studied and the richest. BRGM reports an average ore grade of 50 g/t. This sector has been worked over a strike of 1,400 m with trenches, adits and cross-cuts. These workings were directed only to the zone above the water table.
In 1932 the conclusions from this exploration activities were: very erratic grades, average vein thickness of about 15 cm, average grade of 20-30 g/t Au inversely proportional to the thickness, gold finesse about 800 with a strong proportion of silver and some bismuth.
Above the water table the vein is enclosed in the laterite and altered gneiss; the presence of a previous working made exploitation more difficult. 20,000 tonnes of mineralized quartz have been estimated above the water table. There is no consistent information on the vein below the water table, but the grades were thought to be decreasing (no enrichment by secondary alteration) and mining conditions obviously more difficult.
All this did not bode well for a mechanised exploitation (at least in 1932) and no serious investment took place. On the sector north of the Andrambo-Maroantovo prospect the average vein thickness is larger (20 to 30 cm) but the grade falls to around 15 g/t Au.
Another recorded primary deposit is Andravoravo-Tsaramiadana which occurs 12 km to the NNW of Vohilava village (see sketch 7/10). Important works were carried out by Mr Hanning around 1910 and were suspended in 1925. It consisted of adits and cross-cuts in laterite. The quartz vein, besides visible gold, contained abundant sulphides with pyrite, chalcopyrite, galena, and mispickel. The vein of Ambodivato slightly more to the north has been exploited in a large quarry.
This prospect occurs to the extreme south-west of the Befody granite, 8 km west of Vohilava village. The prospect is very close to the granite-micaschists contact which has been explored by adits (Besairie, 1966 p 281a). Nearby, the prospect Lavakianja is noteworthy for its abundance of quartz eluvions.
To the north of the Vohilava-Ampasary goldfield, the Itrozona River is a tributary of the Vatovandana which flows into the Indian Ocean to the north of Masomameloka. At Beando, 3 km to the south-east of Beando village, a 40 cm-thick quartz vein has been exploited by a trench 80 m long with a few shafts.
A small 5-stamp mill was installed and operated by a hydraulic wheel. In 1912 this plant produced 36 kg of gold. In the same sector the placers of Androrangapetraka and of Ambodiara have been worked. Other artisanal works took place at the Ambalafary and Sahaberiana rivers.
This locality, 18 km north-east of Vohilava, hosts some primary mineralisations in gold-bearing quartz veins, lateritised and therefore enriched. An open cast mine was opened to exploit sericite-schists abundantly intruded by quartz-pegmatitic veinlets in a mylonitic zone. There are records (Besairie, 1966 p 281b) about the presence of quartz-sulphide veinlets up to 40 cm thick with grades of 8 g/t Au and 9 g/t Ag. At Fotobato, 15 km to the NNE of Vohipeno village, there occur large quartz lenses with traces of sulphides: these lenses are very irregularly distributed and they are apparently grading 10 g/t Au.
An abundant sulphide mineralisation is located in the veins near the faulted zone of Andranotonga 12 km to the north of Vohilava. Some quartz veins with biotite, tourmaline and fine pyrite and mispickel, weakly mineralised in gold and silver, occur near the falls of the Sahamatrano River on the track Andranotonga-Tanambao. On the Ambalavary and Ambatoharanana rivers wulfenite (PbMoO4) has been found. The Besonjo creek is noteworthy for abundant quartz with sulphides; but no significant gold values are reported.
On the upper course of the Sahandriambo River fluvial terraces and flats are almost nonexistant and mining took place from the river itself. The actual river bed is certainly very rich as all its southern tributaries are auriferous from the Ambodimanga R. onward.
The placers on the Ambatofotsy R. have produced 76 kg of gold between 1906 and 1928 after being drained by means of a diversion canal 2,200 m long. Around 1910 two meanders upstream of the Antapandrano R. were also drained. These and several other works aimed at tapping the region’s unquestionable alluvial gold potential have not apparently been overly successful. Besairie (1966 p 281b) mentions difficulties in bringing water to the various placers but this explanation sounds unconvincing (IMR’s opinion).
Several primary prospects are known in the Maha R. valley. Anajaridaina prospect, 2 km to the west of Morafeno village, is in a mylonitic zone rich in quartz-pegmatitic veins which are rather discontinuous. Another prospect, Manakana, 15 km west of Anajarindaina, is in numerous veins of chlorite-rich schists: the paragenesis consisted of pyrite, chalcopyrite, rutile and some gold.
The two prospects of Ambia-north and Ambia-south, 7 km to the north-west of Morovato, were exploited in the 1930s. The mineralisation was hosted in sulphide-rich quartz veins occasionally associated with calcite or magnetite.
The alluvial deposits of the Maha are in terraces and flats. Most of the terraces have been more or less exploited in the past. The flats are now largely covered by coffee plantations. In the terraces a loose conglomerate of variable thickness (0.2 to 2 m) is overlaid by sterile lateritic clays 3 to 7 m thick. The gold-bearing alluvions are very clayey and require a thorough washing (“d‚bourbage”). The ore grades range between 0.3 and 2.5 g/m3.
Several primary prospects are known in the valley of the Saka River. The already mentioned Namolika prospect is one of these and it has been worked underground. Similarly at Tsaramiandana a gold-bearing quartz vein has been exploited by shafts. The largest known alluvions are: Andakatsiefo, Saka-Manama and Ambodiara. These and others are only a few km away from Vohilava village (sketch 7/10). At Fadransana on the Bealana River, 34 kg of gold was produced between 1911 and 1928. Not all these alluvions have been exhausted. Some were still being worked by “artisanal” means at the time of compilation of the present report (1995).
Prospection on the river-beds of Saka and Maha rivers
As this report is more oriented toward the hard-rock gold potential rather than the alluvial one, the operations on the Saka and Maha rivers will receive only a rapid coverage mainly from Besairie (1966, 1969) texts.
A exploration program was carried out on these rivers between 1939 and 1940 with a banka drill. This work has resulted in the observations below, which are essentially applicable to most rivers on Madagascar’s east coast as the hydrographic regime is essentially the same.
The rivers of the Saka and Maha type have a bedrock of very irregular surface with numerous rapids and waterfalls which explains the great irregularity in the thickness of the alluvions. The alluvions are only coarsely classified and they are reworked at every flood, the gold bring redispersed within the alluvions. Local concentrations vary from season to season. These concentrations occur either at the surface of the alluvions or in the black sands [magnetite?] within the alluvions. These concentrations are generally at the borders of the alluvions, and slightly downstream of eroded banks or mined terraces.
Six exploration augers-drills on the Maha in 1939 indicated an average grade not above the 0.1 g/t Au. On the Saka River 48 Banka holes have been sunk. The only grades worth mentioning are:
These holes clearly showed that if the present alluvions appear rather rich at the surface, they are disappointingly poor at depth. The alluvions’ thickness ranges between 2 and 6 metres. Gold mining by diving was limited to the upper part of the alluvions.
This exploration campaign indicated that the alluvions could not be exploited by conventional dredges. In view of this the Madagascar Mines Service built special equipment (patent NeviŠres) which could suck the alluvial sands at a given depth without being obliged to absorb its sterile parts.
The dredge also was equipped with a water jet to facilitate the disgregation of the alluvions and an suction duct. The production of this contraption was 6 m3/h in medium-sized gravels and up to 15 m3/h in sands and grits. During experimental tests at 4 m depth the dredge recovered, after a water injection of one minute and an aspiration of one minute, 65 % of the lead and 55 % of the gold that was sunk in the alluvions. It was estimated that this type of small dredge was likely to give very satisfactory results in stable alluvial deposits even in coarse gravels.
The dredge was then tested directly on the Saka with the aim of exploiting some the sectors indicated most favourable by the Banka drills. The results were extremely poor. They showed that [predictably] there was no continuity between two holes with high gold grades. It was therefore impossible to estimate an average grade from the drill-hole results and the average grades obtained by this primitive suction dredge were always inferior to the grades indicated by Banka drills.
In reality the description of the gold alluvions of the Maha and Saka rivers are no different to the ones in tropical rain forests (the eastern part of Madagascar) with a hydrography draining from gold-bearing laterites.
Some parts of Papua New Guinea, British Guyana and of Zaire’s Kivu province present the same conditions. The problems of efficient gold recovery from comparatively small and erratic placers are not new. Literally thousands of small floating dredges, some of them very ingenious, have been built in Australia, South-East Asia and South America for the exploitation of these placers, invariably with mixed results.
In the 1980s the French BRGM (through its subsidiary Soditra – Sodiloc), built a state-of-the-art small dredge which, although built and tested in Madagascar, had the world market in mind. These dredges, called “Dragor 6″” and “Dragor 4” (sketch 7/1/1), are not significantly different from US models developed two decades before.
The general geology and morphology of Madagascar does not seem favourable to the formation of large alluvial gold deposits like those of Brazil, Venezuela or some parts of Papua New Guinea. Exploration for these types of deposits will probably be outside the aims of large foreign investors to whom this report is aimed.
7.2.8. BEFORONA GOLD DOSTRICT
Location and History
The Beforona gold district is bisected by the main road and railroad linking Antananarivo to Toamasina (formerly Tamatave), the main Madagascan port on the east coast. This gold district can easily be reached by 124 km of good, surfaced road from Antananarivo (sketch 7/15).
Beforona village, central to the gold district, has no facilities, but 30 km to the east the small town of Moromanga (comfortable hotel, telecommunications) is a convenient base. Most of the deposits of the Beforona gold district can be reached only by 4WD vehicles or on foot.
Most of the deposits of this goldfield were already productive in 1900 when this district was, in terms of production, the second largest in Madagascar.
The gold deposits of the Beforona district are hosted in migmatites and amphibolites of the Beforona group (C5) of the Vohibory system which have been dated at 2,700 MA (Besairie, 1964). The gold mineralisation has probably been introduced or significantly remobilised in the major tectonic event of 2,104 MA, but later remobilisations cannot be excluded.
Regionally, the gold-bearing migmatites and gneiss of the Beforona gold district seem to be the extension of similar formations of the Mananjari system of the Vohilava-Ampasary gold district, 500 km to the south. The main difference seems to be that while the Vohilava-Ampasary gold is hosted in a Fe-Ca-Mg metamorphic series, the Beforona gold is hosted in a more sialic environment: possibly the metamorphic grade is also higher (migmatites rather than schists) than the Vohilava-Ampasary series.
Also similar to the Vohilava-Amposary is prevalent north-south regional tectonics. The Beforona district’s known mineralisation consists of free-milling gold and gold in Cu-Fe sulphides disseminated in quartz veins.
Table 6 lists only three recorded deposits, all primary, for the comparatively small and understudied Beforona gold district. Significantly, 27 of them are primary.
The important Marovato deposit is only 15 km from Rogez Station on the Tananarive-Toamasina railroad. It is one of the last primary gold deposits to have been industrially worked in Madagascar: the deposit was abandoned in 1952. It was during Wold War II that Marovato attracted new interest and investment from the Madagascar Service of Mines Exploitations (Mr A Lenoble). The Marovato deposit consists of three gold-bearing quartz veins conformable within the migmatites:
VEIN I: striking over 4 km and prospected by trenches, shafts and galleries at several levels over a length of 405 m and a depth of 35 m. Its thickness ranges from 35 to 150 cm.
VEIN II: striking about 1,800 m: only small workings have taken place in this vein.
VEIN III: rather far apart and less rich than the previous two veins.
The ore is in quartz with auriferous pyrites and chalcopyrites and a few zones of free-milling gold. In 1945, at Marovato, there was 520 m of underground development and 70 m of shafts. Power was supplied by a hydraulic plant of 30 CV. Mr Lenoble estimated known reserves of 5.5 tonnes of gold (177,400 oz) at unreported cut-off grades.
Preliminary tests over 250 tons of ore yielded 3,025 kg of gold or 12 g/t Au. At the time it was estimated an industrial recovery of 10 g/t plus about 7 g/t Au in the sulphides. A further, well quartered, sample treated by fire assay gave an average ore grade of 13-17 g/t Au. The plant was destroyed by fire in 1947 although some minor prospecting activities took place until 1952 when the mine was definitely abandoned.
The Grigri prospect, 45 km east of Moramanga, raised high hopes in 1905 but ended up as total failure after some underground workings. The main deposit is in a large quartz vein 80 m long, 10 m thick at most, and at least 13 m deep. Underground surveys (tracages) were carried out at several levels. This mass of white quartz showed an average grade of about 6-7 g/t Au with occasional pyrite-rich zones with higher grades. Gold occurs either as an inclusion in pyrite or, more rarely, as free-milling.
Other smaller, but not richer, gold-bearing quartz veins occur nearby the main Grigri prospect.
7.2.9. ANDRARONA GOLD DISTRICT
Location and History
The Andrarona gold district occurs in the extreme north-east of the island in the Masoala peninsula, north of the Antongil Bay. This is a rather minor gold field, often quoted in the literature as Antalaha, from the omonymous seaside town.
The Andrarona gold district can be reached either by a twice-weekly plane to Iharana (Vohemar) or Sambava townships and then by by road, mostly unsurfaced to the village of Antalaha (with only primitive accommodation). Conversely, it is possible to reach Antisarabato-Antalaha by charter plane. The best base for the Andrarona gold district is the town of Sambava (hotel, telecommunications and other services) 90 km to the north of the goldfield (see sketch 7/13).
This small gold district has officially produced only 270 kg Au between 1905 and 1920 – the period of major production for Madagascar.
The geology of the Andrarona gold district is unique in Madagascar. Andrarona is the only district where gold is clearly related to granitic intrusions. Although the gold mineralisation occurs in Precambrian schists and micaschists of the Beforona group of the Graphite System, the mineralising episode appears related to the emplacement of the Antonigil granites tentatively dated at 770 MA (Besairie, 1964), but possibly older.
However, there are reservations about these Antonigil granites being the primary source of gold, as in some works consulted these granites appear much older, and possibly cratonic (Hottin, 1972). On the other hand the BRGM (1985) points to a possible – and highly unlikely – Devonian age for the Andrarona schists. The lack of modern geochronology of the region makes these discussions rather futile. We also note that the consistent presence in the same goldfield of two different gold finenesses (975 and 850) could indicate a multiple origin of the gold.
There is no obvious tectonic control in the Andrarona gold deposits but the region is strongly tectonised, being in one of the regions of maximum stress linked with the break-up between India and Madagascar.
The recent activities of artisanal miners in the previously unknown region of Marantsetra (see sketches 5/1, 7/1 and 7/13), about 120 km to the south west, may indicate that the Androrona gold district could be much larger than previously thought.
Table 6 lists 11 recorded deposits, all primary, for the Andrarona gold district, five of them belonging to the comparatively rare a4 genetic type (see chapter 6.5).
This primary deposit, and relative alluvions, occurs 18 km south of Antalaha and, to date, has been the largest known occurrence in the district. The deposit apparently lies at the contact zone between a granitic massif (Masoala granite) and the schists and quartzites of the Beforona group. The schists are cut by a swarm of quartz veinlets both conformable or uncomformable. The quartz is milky or blue-coloured, often with tourmaline or rutile needles. Gold occurs in pyrite, although alteration has occasionally liberated free-milling gold. Grades are reported at between 6 and 7 g/t with occasional peaks of 30 g/t.
Besairie (1966, p 270b) mentions this primary deposit occurring to the west of the Antsahivo River, where a quartz vein was followed over 200 m by superficial working. Recorded grades were around 30 g/t Au. This large vein, almost concordant with the schists, was dipping 75§ and is cut by several veinlets forming a stockwork pattern with an average grade of 6-7 g/t Au over an average thickness of about 1 m. Measured reserves have been calculated at 86 kg of gold with possible reserves of 172 kg. We ignore the methods of these calculations (IMR’s note).
At Andrarona, in the upper valley of Marambo, gold-bearing quartz (milky, blue or haline) veins with rutile and tourmaline inclusions have been mentioned but without further details (Besairie, 1966 p 270a).
In the Andrarona goldfield several, presumably small, alluvial deposits have been recorded. Among these: Andongozabe, Ambodihintsy, Ambalambato, Andranomena and Antsahabe.
7.2.10. VAVATENINA GOLD DISTRICT
Location and history
The Vavatenina gold district is located 80 km north of the provincial capital, and major port, of Toamasina (formerly Tamatave). It can be reached by daily flights (Air Madagascar – Boeing 737) to Toamasina and by 157 km of surfaced road to Vavatenina: but this village though central to the goldfield offers no facilities. The best base to this goldfield is the pleasant seaside town of Fenoarivo (hotel, telecommunications, landing strip) 40 km of surfaced road to the east of the goldfield.
Vavatenina gold district is the smallest in Madagascar with a known extension of only a few tens of km2. In the past (Besairie, 1966) the Vavantenina goldfield was considered jointly with the much larger Berofona one and statistics are therefore rather confused.
In spite of its reduced area the Vavatenina district has been a significant gold producer in the past: 40 kg of gold was produced in only six months in 1902. But production decreased sharply from 1904 onward. Production took off again from 1941, with 8.8 kg produced in 1942 and 11 kg in 1944. Present production is entirely due to artisanal miners.
The geology of Vavatenina is charaterised by the predominance of of biotite-micaschists, occasionally with kyanite. These schists are frequently cut by pegmatitic swarms and quartz-feldspar veinlets which correspond to the migmatitic front in the Ambodiriana group (C7) of in the Vohibory system. These micaschists have been dated at 2750 MA and the regional tectonics show strong faulting striking 10§ to 15§ to the east (Besairie, 1964, Feuille du Centre). There are no obvious granitic intrusions nearby.
The average gold finesse is 950, possibly pointing to a sulphide-poor environment (IMR’s note). Practically all rivers and streams in the region are auriferous, although they all are rather small: never more than creeks, which limit their potential. A possible correlation of this district with the Beforona gold district to the south in very similar geological and tectonic conditions is tempting, as both are hosted in the Vohibory system (see Plate 1).
The only two (but primary) deposits listed in Table 6 point to the relative lack of knowledge of the apparently small Vavatenina gold district.
The three individual gold deposits recorded are about 10-13 km west of the Vavatenina village (Besairie 1969, feuille Tamatave). There no available descriptions of these deposits. A thermal spring 8 km to the north of these prospects is well worth a geochemical characterisation (IMR’s opinion).
8. GOLD IN MADAGASCAR: THE OPINIONS
8.1. POLITICAL RISK
As a consequence of poor information, Madagascar has been rather neglected by the wave of major investors now scouring Africa for mining opportunities, particularly in gold; with South African, North American and even Ghanan mining companies leading the pack.
Madagascar is still seen as an exotic country with untested democratic and market convictions. This is not accurate. Since 1992 Madagascar’s commitment to a liberal democracy has been unquestionably sincere, although the legacy of nearly 20 years of centralised military rule is heavy.
The World Bank, among others, is a willing creditor to Madagascar. Madagascar is member of the Multilateral Investment Guarantee Agency (MIGA). Taking these aspects into consideration, the “risk” factor of Madagascar is not higher than for some other regions of Africa.
Less so the “geological risk”. Here the western investors feel rather uncomfortable. A casual business trip to Antananarivo does little to dispel this feeling. Gold exploration in Madagascar requires both a serious commitment and plenty of homework. These aspects will be covered in the next chapter.
But Madagascar’s new Mining Code of August 1990 (law No. 90-017) and other investment laws are adequate to cover potential mining investors.
Short-term political risk
It must be understood that since the demise of communism as a viable economic doctrine the concept of “political risk” in mining ventures has changed radically.
Gone are the days where “repatriation of profits” was a major consideration. With even Castro’s Cuba now guaranteeing unrestricted repatriation of profits for foreign investors, the problem doesn’t seriously present itself any more. A country that does not accept that is simply not serious about attracting mining investment in an increasingly competitive African scenario (Otto, 1995). A similar consideration is applicable to the other standard requirements for foreign
Security of tenure,
Fixed tax terms
Fixed environmental requirements
These requirements should in any case be firmly reviewed, point by point, with the appropriate Malagasy authorities, and guarantees obtained before any major exploration commitment is made.
Large mining companies should avoid demanding a “one stop shop” for formal approval of their exploration ventures. The often-mentioned “one shop stop” concept is simply unrealistic. In Madagascar, as in most parts of the developing world, this approach can only encourage middlemen and dubious “agencies”, arouse public resentment, and open legal ways to later renege on the deal concluded. There have been recent cases to this effect in India and some African countries.
The political risk in any country, especially an untested and unusual one such as Madagascar, can be effectively reduced by gaining an intimate knowledge of the country’s political climate. Every day spent in aquiring a better understanding of Madagascar’s objectives and aspirations will lessen the political risk of any major venture. Conversely, to take any African country – and Madagascar in particular – for granted could only invite unexpected difficulties.
Central to the concept of risk is, clearly, the absence or the presence of favourable geology. However encouraging the local regime or favourable its commercial climate, no exploration investment could be sanctioned unless the country had high prospects for the discovery of a gold deposit of the size and profitability rate of return decided upon by the investor.
The self-explanatory sketch 8/1 gives a modern assessment for gold exploration in selected African countries, taking into account:
In this assessment Madagascar ranks on the same level as Burkina Faso, Ethiopia and Tanzania. It also ranks way above Zaire but, understandably, below Ghana and Zimbabwe.
A last point. Madagascar, in virtue of its unique and very fragile ecosystem, has long been the darling of various conservation groups. Such groups have been vociferously hostile to, for instance, a large scale ilmenite prject in the south of the island long before its economic viability was proved (see chapter 5.3.3 of this Database). This type of risk can be minimised by opening dialogue, on relevant issues, with the appropriate authorities (national, local or international) at a very early stage of any gold project.
Long-term political risk
Long-term political risk is always more difficult to evaluate. It should be remembered that the recent opening and liberalisation of most African countries is only five years old and may very well be just an extended honeymoon.
There are massive, unaddressed problems in Africa: in particular its rapidly expanding population, with vastly insufficient new investments to cope with it. In this scenario, the menace of future coups d’Etat, civil unrest or ethnic violence cannot be easily dismissed.
In Madagascar’s case, however, some advantages over other African countries are apparent:
– Madagascar’s racial or ethnic tensions are not nearly as strong and divisive as in other parts of Africa. The latent hostility between highland and coastal tribes (an hostility expolited in the past by the French) has nothing of the intensity of the Hutu-Tutsi in Central Africa, the Xhosa-Zulu in Natal or the clannish rivalries of the horn of Africa and Kenya.
– Even at the height of Malagasy military coups and counter-coups of the years 1972-1975, the casualties were kept to a minimum. Malagasy people dislike violence.
– The fact that Madagascar was a cohesive society long before European colonisation adds an element of stability rare in Africa.
– Madagascar’s lack of borders and neighbours make any armed destabilisation more difficult than the rest of Africa.
– Armed banditism on the scale of Mozambique or Uganda is not a present Malagasy feature and an unlikely future one.
– After 20 years of disastrous central planning and declining living standards, the average Malagasy is genuinely looking forward to stability and economic progress.
– Gold mining is a rather self-contained activity almost independent from heavy infrastructure, which makes it far less vulnerable to external turmoil.
8.2. GEOLOGICAL POTENTIAL
This is the paramount consideration. If a gold deposit of the size and profitability sought by the investing company does not exist in Madagascar there is no reason for the company to be there at all, regardless of any other favourable circumstance. A simple point, but overlooked surprisingly often.
Reflecting on gold’s potential in Madagascar, H. Besairie (1966) presciently lamented that “… on ne s’est pas souiciŠ de relever les teneurs moyennes…” [… The average grades of the deposits have not been recorded… ] (Bes. 271b). This is only one of the many difficulties facing an Anglo-Saxon geologist trying to form an informed and objective opinion on Madagascar’s gold potential.
Other constraints are:
– Lack of recent (post-1969) literature on Madagascar’s goldfields;
– The fact that practically all the previous literature on Malagasy gold, although abundant, is very difficult to gain access to, is over-descriptive and invariably in French, and technical details such as cut-off grades, metallurgical plants used and recovery rates achieved etc. are usually omitted;
– The fact that Madagascar is essentially an agricultural country, rather than a mining, or even an industrial country, make a meaningful dialogue with the authorities far more difficult than for some other African countries;
– The neglect and the lack of funds that have affected both the Geological Survey and the Mining Service of Madagascar in the last two decades.
Alluvial Gold Potential
Madagascar has produced more than 70 tonnes of gold from 10 documented goldfields, which in the last 15 years have considerably expanded in size.
For various reasons, gold production in the past was mostly from alluvial operations, and this long before suction dredges became the efficient tools they are today. This augurs well for the development of a lively middle-sized local industry. Contrary to most east African countries, Madagascar has more than 30 rivers where small gold dredges can operate (see also Table 2 and sketch 7/1/1).
A standard Keene 2«” suction dredge (or equivalent model) can easily go through m3 of gravel per hour (Thoronthon, 1979; p 50) and operate in as little as 50 cm of water. In Madagascar there are several hundred kilometres of river beds which have never been properly dredged.
Among the Malagasy gold districts that seem to offer outstanding potential for small river dredges are the Maentavana, the Ambositra-Antananarivo and the Vohilava-Ampasary. These three gold districts possess three important conditions for sustaining medium-scale dredging:
1. The area drained is large and it is heavily mineralised;
2. The fluvial regime is very dynamic;
3. The gold of the district is coarse in nature.
Regardless of its potential, alluvial gold mining in Madagascar is not recommended to the reader of this Database.
Foreign investors are traditionally attracted by large primary gold deposits where the recent lessons of, say, Australia and North America can easily be applied. A sharp separation between small and medium-sized alluvial operations (better suited to Malagasy entrepreneurs) and large primary ones (better suited to well-capitalised firms) will be beneficial to all parties involved.
Primary gold potential
The primary gold deposits of Madagascar mostly occur in gold-bearing quartz-vein systems frequently associated with sulphides. With the exception of the Betsiaka gold district in Madagascar’s extreme north, all other districts are in Precambrian terrains, which form two-thirds of the island. Geologically, these terrains are related to other gold-producing areas in southern Africa and probably India.
Madagascar’s gold deposits are essentially of the “mesothermal lode gold” type, which account for more than 18% of world production. In this respect they are, genetically at least, similar to the deposits in the Archean shields of Canada and Australia, and to a lesser extent, those of western Africa, Brazil, Venezuela and Tanzania. Exploration for these types of deposits has increased dramatically in the last 10 years, with considerable success.
The traditional approach to the exploration for “lode gold deposits” is a thorough reassessment of ancient workings. The Canadian Helmo deposit, an outstanding gold discovery of the 1980s, had a history of minor development dating from 1869.
Most of Madagascar’s old underground gold mines, more than 50 of them, some with several hundred metres of underground development, were considered uneconomic by the early 1920s.
This was precisely the situation of Western Australia before the gold boom of the late 1970s. In both cases grades below 10/g/t Au were seldom mined and the prospecting techniques were most primitive. In Madagascar they often consisted of following the quartz veins at the surface and exploiting only the rich secondary enrichments between quartz veins and overlying laterites.
Madagascar offers plenty of scope for modern exploration. Its well exposed terrain is ideally suited to remote sensing, particularly because of the strong relationship between Madagascar’s goldfields and tectonics (Madagascar is arguably the most fractured fragment of Gondwana).
The enormous advancement in modern soil and rock geochemistry have all but passed Madagascar by. So has the application of metallogenic models developed in the last 20 years in regions geologically similar to Madagascar – in some cases with outstanding success. In spite of some minor French and Soviet involvement, Madagascar’s gold resources have not really been assessed in recent times.
In exploration for primary gold deposits the concept of size is very important. South African gold mining companies, few in number, very large and bent on the necessity of replacing their increasingly uncompetitive mines, will probably be uninterested in a project with less than 1M oz of contained gold. A possible but a totally speculative type of deposit in underexplored Madagascar.
On the other hand the very successful and well diversified Australian gold sector operates more than 131 mines with an average production of around 60,000 oz/y. (Pollock, 1995). This a far more realistic target for Madagascar’s presently known potential. Table 2 of this Database lists seven gold districts thought to have high potential for this type of resource.
The exploration for medium-sized gold deposits (say 50.000 to 300.000 oz Au) seems to make particularly good sense in Madagascar: they are statistically more frequent, easier to finance and develop, gentler on the environment, more attuned to the decentralisation will of the Malagasy authorities and likely to produce less economic and regional distortion of Madagascar’s fragile economy.
In any case, exploration for primary gold in Madagascar will demand commitment. To reinterpret the incredible wealth of accurate, if obsolete, geological information will require time and skill. The country has a proud history of self-sufficiency and gold is already its major mineral product.
Predictably, the Malagasy authorities (already bitten by some recent, hare-brained schemes regarding their gold resources) will require their potential investors to be serious. Given Madagascar’s unquestionable geological potential this is only fair.
9. CONCLUSIONS AND RECOMMENDATIONS
Australian experience is relevant to Madagascar in many ways.
Many goldfields which were very productive at the beginning of the century came to an abrupt halt in the second decade of this century. Classical example is Charter Tower gold field, the fifth largest in Australia where not an ounce of gold has been pulled out of the ground since 1917 and only recently being reinvestigated. In previous years 6.6 million oz was extracted from high-grade quartz veins which bear some similarities to most of Madagascar’s goldfields. At today’s price this means well in excess of US$ 2 billions. Then the gold price fell 50% between 1910 and 1920, mining operations were small and inefficient, and labor became scarce and expensive because of other opportunities.
Some authors (Borg 1995; p 74) have given a good account on how modern exploration techniques can be applicable to gold exploration and evaluation situations in a variety of different anomalous environment. Several relatively inexpensive techniques such as soil, rock and gossan sampling, detailed exam of old working and known mineralisation have given good results in almost all cases and particularly for the associations gold-pyrite which is very common in Madagascar.
In considering gold ventures in Africa the objectives of the explorer are all important: the five major South-African gold producers, bent in substituting what are now very deep and costly mines would not seriously consider a gold resource below 1 million oz gold (or about 30 kgs in situ resources). So probably will be the view of some of the major Australian mining houses: BHP,CRA, WMC, etc. On the contrary for some small speculative company from Perth or Toronto the main consideration would be the “profitability” of the venture and much smaller resources can be considered provided the grades are there: this indeed has been the philosophy in Western Australian goldfields for the last 15 years.
Lastly some medium-sized companies consider their strategic medium term objective to become a plus 250.000 ounce gold producer through mining development in Africa (Cowley, 1995; p 146). At this stage of our knowledge Madagascar offers scope to all these objectives.
The metallic associations of many Madagascar’s gold districts would make the modern use of soil and rock geochemistry highly effective, much as it has happened in geologically contiguous Tanzania.
Countries under consideration in Table XX – elaborated jointly by the private industry and the UN – show various elements of risks for mining investment. Without examining each item individually for Madagascar let’s consider the most important.
Geological criteria – geological risk.
This brings in what South African geologists operating in Africa (an ever-growing breed) call geological risk. That is the geological uncertitude about the environment in which one is operating. With only minimal government funded geological exploration having taken place since independence of most African countries this geological risk is large and widening. By and large the geological and exploration models developed in Australia, North and South America in the last, say 30 years, have not yet been applied to most of Africa, Madagascar included. Mineral exploration has been poorly funded since the 1960’s in Madagascar and often directed to energy resources: uranium, oil and gas, coal. At Government level Madagscar has amost missed out the gold exploration “boom” of the last 17 years.
This tends to put a gold exploration company in a “catch 22” situation: for knowing Madagascar’s gold potential some exploration is unquestionably needed, but then one doesn’t know if that exploration (with the inevitable arrangements with the Malagasy authorities that this entails) is warranted. It is up to any company, in view of its objectives and exploration philosophy to make this type of decision. In a way the present report has been made precisely with the view of lessening geological risk by combining together what is publically known about gold in Madagascar.
Two considerations are worth keeping in mind:
1) that for the forseeable future the geological risk on gold exploration in Madagascar is not going to be significantly decreased and
2) That medium sized gold deposits (say 50,000 – 500,000 oz Au) are statistically more frequent than very large ones (1,000,000 – plus oz Au) thus lessening the geological risk.
Agrawal, P. K., Pandey, O. P. and Negi, 1992. Madagascar: A continental fragment of the paleo-super Dharwar craton of India. Geology Vol 20 p 543-546
Ainsworth, J., 1995. Mining development in Africa. in Conference “Africa, the New Mining Frontier, J.B. Were & Son, Sydney, 11p
Andriamirado, R., 1976. Quelques remarques sur l’ancienne position de Madagascar par rapport … l’Afrique. Acad‚mie des Sciences Comptes Rendues, ser D, v. 282, p 2041-2043
Anhaeusser, C. R., 1976. The nature and distribution of Archean gold mineralization in southern Africa. Mineral Science and Engineering, 8 p. 46-84
Antonides, L. E. et al., 1988. The Mineral Industry of East Africa. In Mineral Yearbook 1988, Vol 3 ; Area Report International, U.S. Department of Interior, Bureau of Mines, Washington, p 75
Audley-Charles, M.G., Ballantine, P.D. and Hall, R., 1988. Mesozoic-Cenozoic rift-drift sequence of Asian fragments from Gondwanaland. Tectonophysics 155, pp 317-330
Bartle, W.W., 1988. The Madagascar mineral sand project – its impact on the market. in Proceedings, 8th Industrial Minerals International Congress , Boston, USA, G.M. Clarke Ed. pp 82-87
Besairie, H., 1964. Madagascar. Carte Geologique 1/1,000,000. In three sheets [in colour]. Antananarivo.
Besairie, H., 1969. Madagascar. Carte Geologique 1/500,000. In six sheets [in colour]. Antananarivo.
Besairie, H., 1966. Gites Min‚raux de Madagascar. Annales Geologiques de Madagascar, Fascicule XXXIV, Tananarive (Two volumes: text anf Figures) p 437 + 93
Besairie, H., 1971. Geologie de Madagascar, 1. Ann. Geol. Madagascar, 35, p.463
Besairie, H., 1973. Precis de Geologie Malgache. Ann. Geol. Madagascar, 36 p. 143.
Bigioggero, B, Cadoppi, P., Costa, M., Omenetto, P., and Sacchi, R., 1989. Late Proterozoic granites of Zambesia (Mozambique) IGCP n§ 225 Newsletter / Bulletin, 2 p 5-7
B.R.G.M., 1985. Or [In Madagascar]. Partial Rapport filed at the Library of the Service Geologique, Antanananrivo p 329-350
Boast, J and Nairn A. E. M., 1982. An outline of the Geology of Madagascar. In Stelhi, F. G. (Ed) ” The Ocean Basisns and Margins”, Vol 6, Plenum Press, p. 649-696
Borg, G., 1995. Multidisciplinary exploration approach for Archean gold and effects of liberalization of mining and trade regulations in Tanzania. “in African Mining ’95”. The Institution of Mining and Metallurgy, London. pp 63-78
Brandon, A. D. and Meen, J. K., 1995. Nd isotopic evidence for the position of southern Indian terranes within East Gondwana. Precambrian Research 70., p 269-280
Coffin, M.F., and Rabinowitz, P.D., 1987. Reconstruction of Madagascar and Africa: Evidence from the Davie fracture zone and western Somali Basin. Journal of Geophysical Research, v.92, p 144-153.
Colvine, A.C. et al., 1988. Archean Lode Gold Deposits in Ontario. PartI: A Depositional Model. Part II A Genetic Model: Mines and Minerals Division , Ontario Geological Survey, Miscellaneous Paper 139, 135 p.
Cowley, P.N., 1995. Investment decisions by an African Gold miner. “in African Mining ’95”. The Institution of Mining and Metallurgy, London. pp 499-414
De Wit, M., Jeffrery, M., Bergh, H., and Nicolayesen, L., 1988. Geological Map of Gondwana, scale 1:10,000,000 with explanation and references, American Association of Petroleum Geologists, Tulsa, Oklaoma.
Drean. P., 1994. Madagascar dans la tempete du mŠtal jaune. Interview to DMD Tirelire, Tananarive p18-19
Embleton, B.J.J., and McElhinny, M.W., 1975. The paleoposition of Madagascar : paleomagnetic evidence from the Isalo Group. Earth and Planetary Sciences Letters, v. 27, p. 329-341
Farah, H.H., 1995. Evaluation of private sector mining projects in Africa by the African Development Bank. “in African Mining ’95”. The Institution of Mining and Metallurgy, London. pp 193-204
Gallieni, J. S., 1900, L’or … Madagascar. Bull. Soc. GŠogr. Comm. Paris
Garson, M. S., and Goossens, P. J. 1980. Comparative Gondwana metallogeny and structures in south-western India, Sri Lanka and Madagascar. 26th Intern. Geological Congress – Resumes (26 Vol.3) p.934
Gilbert, M., 1989. Second World War. Fontana/Collins. p 846.
Govett, M.H. and Harrowell, M.R., 1982. Gold. Australian Mineral Economics P/L, Special publication, Sydney, Australia, 455 p
Hester, B.W., 1990. Gold opportunities in Tanzania: DMBW Inc. (Denver), p 91
Hottin, G., 1964. Le gisement d’or d’Andravoravo. Rapp. ann. Serv. Geol. Mad. Tanarive
Hottin, G. 1976. Pr‚sentation te essai d’interpretation du Pr‚cambrien de Madagascar. With Map at 1:2,500,000; Bull. BRGM. (2ieme Ser.), sect.IV : p 117-153
Hodgson, C.J., 1993, Mesothermal lode-gold deposits. In: Kirkham, R. V. et al. “Mineral Deposits Modelling” Geological Association of Canada, p 635-678.
Hoffman, P.F., 1991, On accretion of granite-greenstone terranes, in Robert, F et al. eds, Greenstone Gold and Crustal Evolution: Geological Association of Canada, NUNA Conf. Volune, p.32-45
Hottin, G., et al., 1966. Sur des gisement d’or du groupe d’Ambatolampi (centre de Madagascar). Madagascar Sem.Geol. C. p 105-106
Humpries, M., 1995. Mineral Development in Southern Africa: the Road to recovery? in “African Mining ’95”. The Institution of Mining and Metallurgy, London. pp 263-284
Katz, M. B. and Premoli, C., 1979 – India and Madagascar in Gondwanaland: a fit based on Precambrian tectonic lineaments; Nature Vol. 1791, pp 312-315.
Kerrich, R., 1989, Geodynamic setting and hydraulic regimes of shear zone-hosted mesothermal gold deposits, in Bursnall, J.T., ed Mineralization and Shear Zones: Geological Association of Canada, Short Course Notes, v.6, p. 89-128
Kirkham, R.V., 1993. Mineral Deposit Modeling. Geological association of Canada Special Paper 40, p 798.
Kroner, A., 1991. African linkage of Pre-cambrian Sri Lanka. Geol.Rundsch., 80: p 429-440
Kronsten, G., 1994. Madagascar. In Mining Journal Annual Review, 1994, London p 142.
Kuehn, S., Ogala, J., and Sango, P., 1990. Regional setting and nature of gold mineralization in Tanzania and SouthWest Kenya; Precambrian Research, vol. 46, p 71-82.
Johnson, C., 1990. Ranking countries for Mineral Exploration. Natural Resources Forum Vol 14 No.3 August
Lacroix, A., 1900. Sur le gneiss aurifŠres de Madagascar. Bull. Soc. Fr. Min t 23, Paris.
Lawver, L. A. and Scotese, C. R., 1987, A revised reconstruction of Gondwanaland, in McKenzie, G. D., (ed.) Gondwana Six: Structure, tectonics and geophysics. American Geophysical Union Monograph 40, p. 17-40
Leitch, C.H.B., Godwin, C.I., Brown, T.H. and Taylor, B.E., 1991, Geochemistry of mineralizing fluids in the Bralorne-Pioneer mesothermal gold deposits, British Columbia, Canada: Economic Geology v. 86, p. 318-353
Matumatsaka, W., and Hangi, A., 1995. Environmentally sustainable artisanal gold mining in the Lake Victiria regions, Tanzania. in “African Mining ’95”. The Institution of Mining and Metallurgy, London. pp 443-456
Mc.Elhinney, M. W., Embleton, B.J., Daly, L., and Pozzi, J.P. 1976, Paleomagnetic evidence for the location of Madagascar in Gondwanaland. Geology, v. 4, p. 455-457
Metcalfe, I., 1991. Southeast Asian Terranes: Gondwana origins and evolution, 8th International Gondwana Symposium, Hobart, Abstracts, p.58-59
Metcalfe, I., 1994. Gondwanaland origin, dispersion, and accretion of East and Southeast Asian continental terranes, Journal South American Earth Sci. Vol.7 pp. 333-347
Mukherjee, A.D. and Bhattacharyya, N.H., 1990. Basin evolution and metallogeny during Mid-Proterozoic in peninsular India. IGCP n§255 Newsletter / Bulletin, 3 p 51-60
Nicollet, C., 1990. Crustal evolution of the granulites of Madagascar. in Vielzeuf, D., and Vidal, P (eds.) “granulites and crustal Evolution: Dordrecht, Nederlands, Kluver, p 291-310
Noizet, G., and Rakotonanahary, R., 1966. Les gisement d’or de Marovato et de Gri-Gri (centre est de Madagascar). Madagascar Sem Geol. C p 139-141
Otto, J M., 1995, International competition for mineral investment: implication for Africa. in “African Mining ’95”. The Institution of Mining and Metallurgy, London. pp 443-456
Pollock, J., 1995. Bloomberg Gold Survey. The AusIMM Bulletin, Nov 1955 Melbourne, p 26-131
Powell, C. McA., Roots, S.R., and Veevers, J., 1988. Pre-breakup continental extension in East Gondwanaland and the Early opening of the Eastern Indian Ocean. Tectonophysics, 155: p. 261-283
Premoli, C., 1976. Tectonic Map of Madagascar, Scale 1:2,000,000. Office National Militaire des Industries Strategiques (OMNIS), Antananarivo, Madagascar, 1 map.
Premoli, C., 1995 – Mineral Potential of Central Africa: an Australian overview. in African Mining ’95. The Institution of Mining and Metallurgy, London. pp 499-414
Pretorious, D.A. and Maske, S., 1976. An issue devoted to mineral deposits in Southern Africa: Econ. Geol. vol 71 N.1, p408
Razafimnantsoa, 1966. Inventaire et possibilit‚s des mineralisations auriferes alluviales. Madagacar Sem Geol. , C. p 143-144.
Ralaimihoatra, E., 1966. Histore de Madagascar. Antonanarivo, SocietŠ Malgache d’Edition.
Roy, B. C., 1963. Metallogenic-Minerogenetic Map of India, 1:2,000,000. First Edition, Geological Survey of India
Saager, R., and Meyer, M., 1984, Gold distribution in Archean granitoids and supracrustal rocks from southern Africa: a comparison. in Foster, R. P., (ed.) “Gold’82: the geology, geochemistry and genesis of gold deposits” A.A. Balkema / Rotterdam. p 53-70.
Scotese, C. R., Gahagan, L. M. and Roger L. Larson., 1988, Plate tectonic reconstructions of the Cretaceous and Cenozoic ocean basins. Elsevier Sciences Publisher
Shiraishi, K., Ellis, D. J., Hiroi, Y., Fanning, C. M., Motoyoshi, Y., and Nakai, Y., 1994. Cambrian orogenic belts in East Antartica and Sri Lanka: implications for Gondwana assembly. J. Geol., 102, p. 47-65
Thomas, A., 1995. Major gold prjects. Mining Magazine, June i955, Londn p 344-346.
Thoronton, M., 1979. Dredging for gold. Keene Industries. Northridge, California. p 243 p.
van Straaten, H.P., 1994. Gold mineralizations in Tanzania – a review. in Foster, R. P., (ed.) “Gold’82: the geology, geochemistry and genesis of gold deposits” A.A. Balkema / Rotterdam. p 673-676
Viljoen, J. M., 1994. Archean gold mineralization and komatiites in southern Africa. in Foster, R. P., (ed.) “Gold’82: the geology, geochemistry and genesis of gold deposits” A.A. Balkema / Rotterdam. p 595-628.
Wopfner, H., 1994. The Malagasy Rift, a chasm in the Tethyan margin of Gondwana. Journal of South East Asia n Earth Sciences 9. (4). p 451-461
Wopfner, H., 1991. Permo-Triassic sedimentary basins in Australia and East Africa and their relationship to Gondwanic stress patterns. Proceeding 7th Gondwana Congress, Sao Paulo, Brazil, 1988; p. 133-146
World Bank (the), 1992. Strategy for African Mining, Technical Paper n.181 Washington, 1-81 p.
Yoshida, M., Funaki, M., and Vitanage, P.W., 1992. Proterozoic to Mesozoic East Gondwana: the Juxtaposition of India, Sri Lanka, and Antartica. Tectonics, 11: p 381-391