Alluvial mining in Brazil was a labor-intensive vocation, and as such, negro slaves imported from Africa, were used extensively for mining operations. The capital city of Salvador De Bahia (est. 1549),on the Bahia de Todos os Santos (All Saints Bay) in Bahia, was a global hub for the Portuguese slave trade, and to this day, the state of Bahia has the highest concentration of blacks in Brazil. Diamantiferous sands and gravel, (cascalho or cascalhão) were hand-dug from river ledges and beds, scooped out of the river bottom by divers (escafandro), or dug from hillsides (engrunada or gruta). Then the diamond-bearing alluvium was washed in sluices of running water, washed again in wooden basins (faísca or lavagem), and finally picked through by hand. The cascalhão occurs in high river-bank ledges, as a combination of gravel and sand, but river-bottom gravel deposits were beneath a bed of clay and silt.
At first, Brazilian diamonds were not as desirable as their Indian counterparts and the fist few years of mining yielded smaller sized stones. As the supply of Indian diamonds dried up, Brazilian stones gained in popularity. In the mid 1700s, Brazilian diamonds were flooding the European market, and prices fell precipitously, but this was reversed as supplies began to dry up in the early 1800s. Brazil's largest rough diamond to date is the "Star of the South," a 254 carat stone found in 1854. Alluvial deposits in Brazil were created by Diamantiferous material being transported from its primary source, within kimberlite intrusions along the Amazonian cráton to the north, and the San Francisco Cráton in Minas Gerais. There are also diamond-bearing kimberlite bodies in the regions of Mato Grosso and Rondônia.
Diamantina in Minas Gerais
Miners prospecting for gold along the Rio Jequitinhonha river, near the town of Tejuco (now Diamantina) in the Minas Gerais region, made Brazil's first diamond discovery in 1725. By 1740, there was a major diamond rush to Minas Gerais' Rio Abaete and Rio Jequitinhonha alluvial deposits, and mining in the region reached its peek between 1785 and 1807.
Miners prospecting for gold along the Rio Jequitinhonha river, near the town of Tejuco (now Diamantina) in the Minas Gerais region, made Brazil's first diamond discovery in 1725. By 1740, there was a major diamond rush to Minas Gerais' Rio Abaete and Rio Jequitinhonha alluvial deposits, and mining in the region reached its peek between 1785 and 1807.
Mato Grosso's Alluvial Diamond Fields
The Portuguese government took possession of the territory in 1748, creating a Colonial Captaincy so as to fully exploit Mato Grosso's mineral wealth. Mining exploration was heavily regulated by the Portuguese Crown during the 1700s, and all extracted minerals were subject to high taxation.
The Portuguese government took possession of the territory in 1748, creating a Colonial Captaincy so as to fully exploit Mato Grosso's mineral wealth. Mining exploration was heavily regulated by the Portuguese Crown during the 1700s, and all extracted minerals were subject to high taxation.
Mato Grosso's alluvial diamonds were first discovered in the 'Morro Vermelho' formation, near the mining town of Diamantino. By 1847, both diamonds and gold were mined-out in the area, and by 1852, the Diamantino prospect was abandoned, bankrupting the Mato Grosso Mining Society.
Chapada Diamantina in Bahia
In 1842, large diamond deposits were discovered along the banks of the rio Mucugê in the mountainous region of Chapada Diamantina (Diamond Highlands), in the Brazilian state of Bahia. This created a diamond-rush to the region, causing a new glut in the European market.
In 1842, large diamond deposits were discovered along the banks of the rio Mucugê in the mountainous region of Chapada Diamantina (Diamond Highlands), in the Brazilian state of Bahia. This created a diamond-rush to the region, causing a new glut in the European market.
Diamonds in Chapada Diamantina's Serra da Sincorá (Cincora) region (aka Lavras Diamantinas) occur in river gravels and sands (cascalhão) along the banks of the rio Mucugê, which is a tributary of the rio Paraguaçu (Paraguassu river). Within the Chapada Diamantina sits the Circuito do Diamante (Circuit of the Diamonds) surrounded by the towns of Andaraí, Mucugê, Palmeiras, and Lençóis.
By 1901 around 5000 slaves worked in the Bahia mines at Serra da Sincorá. The Sincorá region is one of the few locations on earth that carbonado is found. Carbonado (aka 'carbon diamond' or 'black diamond') is a rare, semi-porous black polycrystalline variety of diamond.
The Chapada Diamantina has a dramatic landscape with high plains, table-top mesas, and steep cliffs or towers known as 'tepuy.' Before the arrival of the Portuguese in the 1800s, the only local inhabitants of the region were indigenous Indians from the Maracas and Cariris tribes. In 1985, the Chapada Diamantina region was made into a National Park, with its headquatrers in Palmeiras.
Brazil's Recent Diamond History
In the 1960's, near Mato Grosso's capital of Diamantino, the 'Mato Grosso Diamond Project' (a 63,000-hectare claim block) created a 'diamond rush' to the area. To date, more than 50 kimberlite pipes have been located, many of which are the most likely source for the region's historic alluvial deposits.
In 1999, nearly 3000 itinerant miners (diamond diggers, or garimpeiros) illegally entered the protected, Cinta Larga ("broad belt") Indian reservation to mine for diamonds. This area lies between the states of Rondônia and Mato Grosso, along the Bolivian boarder. Mining was forbidden within the 'Roosevelt Reservation' in order to preserve the indigenous 'Cinta Larga' people's homeland, but the Cinta Larga are allowed to engage in 'small scale prospecting' (garimpagem), if the labor is done exclusively by indigenous Indians. Federal Police evicted the garimpeiros, but the government estimates that as much as $50 million were smuggled to Belgium.
The Cinta Larga attacked a group of illegal prospectors in April of 2004, killing 41 of them. Since the incident, tensions in the region have eased, and in October 2004, Brazil received accreditation to obtain a Certificate of the Kimberley Process. Diamond mining within the Roosevelt Reservation could be worth an estimated $3.5 billion annually.
Future Diamond Mining in Brazil
The most promising locations for any future Brazilian diamond mining activity are in the states of Matto Grosso and Bahia, and in recent years diamond mining activity has picked up in the region. Diagem Inc. in cooperation with Rio Tinto (Rio Tinto Desenvolvimentos Minerais Ltda) is still surveying for new diamond finds in Brazil. There have been several promising finds at its 'Collier-04' kimberlite pipe, located in the Juina diamond district of Mato Grosso, Brazil.
Exploration in the Diamantina, Regis, Santo Antonio, and Serra da Canastra regions of Minas Gerais is currently being conducted by Brazilian Diamonds Limited, CODEMIG, and Mineração Rio Novo Ltda.
Word Resources and Supply-2006
According to data of the Mineral Commodity Summaries – 2007, the world reserves of diamond changed little as compared to 2005, but it is worth highlighting that the data on the world availability of diamonds are still inaccurate and that the world source for consultation is limited solely to the reserves of uncut diamonds, of the type industry. Congo is the country that holds the largest reserve of diamond, contributing 27.4% of the world reserve.
Brazil contributes only 2% of the world reserve and according to consolidated data of the Annual Extraction Report 2007 – base year 2006, out of the 24 Mct (millions of carats) declared by miners, 19 Mct are from secondary deposits and 5Mct from primary deposits. The State of Mato Grosso has the largest declared reserve of Brazil, and contributes 77% of the secondary reserve and 100% of the primary reserve.
The world supply in 2006 was of about 176 Mct, with a small decrease as compared to 2005 of 0.6%. According to data of the Kimberly Process Certification Scheme, the biggest producers were Russia (21.84%), Botswana (19.53%), Australia (17.05%), and Congo (16.51%), which together contributed 74.9 % of the world production of diamond in 2006.
It is estimated that Brazil, in 2006, produced circa 0.2 Mct of diamonds, contributing only 0.11% of the world production.
DOMESTIC PRODUCTION
According to the official records, the Brazilian production of uncut diamonds (industry and gem) in 2006 was of 181.350 ct, and the State of Mato Grosso produced 96.4% of the diamonds, Minas Gerais 3.4% and Goiás only 0.2%. It is possible to notice a drop of approximately 41% in the production of diamond as compared to 2005, which occurred due to the interdiction of exports of uncut diamonds, in the period from February to September, 2006, brought about by “Operation Carbon”.
In the corporate segment, the major producers of diamond were Chapada Brasil Mineração Ltda (Chapada dos Guimarães – MT) that produced 10.312ct; S.L. Mineradora Ltda (Juína – MT) that produced 8.457ct and Mineração Rio Novo Ltda (Diamantina – MG) with a production of 5.514ct. But most of the Brazilian production still comes from artisan mining, from areas object of PLGs – Regime of Permission of Artisan Extraction. In 2006, only in Juína, the PLGs produced circa 151.000ct of diamond, which corresponds to approximately 84% of the Brazilian production.
Foreign Trade
Exports
In 2006, the Brazilian exports of uncut diamonds were of 90.017ct, producing revenues of US$ 5,415,769.60. As well as in production, exports featured a drop for the already mentioned reasons. The drop recorded in volume (ct) was of 25% as compared to 2005 and the drop recorded in the revenue (US$) was of circa 72%. (In 2005 Brazil exported 280.519.38ct, producing revenues of US$ 19,052,767.86).
In 2006, the Brazilian exports of uncut diamonds were of 90.017ct, producing revenues of US$ 5,415,769.60. As well as in production, exports featured a drop for the already mentioned reasons. The drop recorded in volume (ct) was of 25% as compared to 2005 and the drop recorded in the revenue (US$) was of circa 72%. (In 2005 Brazil exported 280.519.38ct, producing revenues of US$ 19,052,767.86).
The countries of destination were: the European Community (86.16%), Israel (9.95%) and the United States (3.9%). The DNPM issued 16 certificates, 10 for the European Community, 4 for Israel and 2 for the United States.
Ongoing and/or Forecast Projects
In Brazil there are several diamond provinces at research stage, mostly in the states of Mato Grosso, Rondônia, Mato Grosso do Sul, Bahia and Minas Gerais and this factor will probably contribute for an increase in reserves.
Vaaldiam Resources Limited develops eight projects in Brazil, 3 advanced projects (Pimenta Bueno – RO, Brauna – BA, Duas Barras – MG), 4 Projects under evaluation (Taboco – MS, Traira – MT, Barra Rica and Gruta – MG) and 1 new project (Aroeira – BA). Project Duas Barras is scheduled for production in 2007, with a capacity of 38.000 ct/year.
DIAGEM International Resources Corporation (Juína-MT) has detected primary sources of diamond and is intensifying research activities, in addition to beginning extraction in 2007 in areas already researched.
- A. Jonathan Buhalis
In Brazil there are several diamond provinces at research stage, mostly in the states of Mato Grosso, Rondônia, Mato Grosso do Sul, Bahia and Minas Gerais and this factor will probably contribute for an increase in reserves.
Vaaldiam Resources Limited develops eight projects in Brazil, 3 advanced projects (Pimenta Bueno – RO, Brauna – BA, Duas Barras – MG), 4 Projects under evaluation (Taboco – MS, Traira – MT, Barra Rica and Gruta – MG) and 1 new project (Aroeira – BA). Project Duas Barras is scheduled for production in 2007, with a capacity of 38.000 ct/year.
DIAGEM International Resources Corporation (Juína-MT) has detected primary sources of diamond and is intensifying research activities, in addition to beginning extraction in 2007 in areas already researched.
- A. Jonathan Buhalis
