1776, Diamantina (Minas Geraes)

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Diamantina is one of my favourite cities; I lost track of the number of times I visited this LusoBrazilian jewel. The city, the region, its diamonds and geology are a common topic in this blog, either as posts (herehere and here) or photo galleries (herehere and here – just click on the links).
Located north of Belo Horizonte, this town classified as World Heritage was the birthplace of main characters in the Brazilian history (Juscelino Kubistchek, President and a central figure of the Brazilian XX century and Chica da Silva, the slave-lady a mythical figure of the XVIII century turned feminist and slave liberation icon).
It was in Diamantina (then Tejuco), around the end of the first quarter of the XVII century, that diamonds were first discovered outside India, setting a new era for the industry.
The Biblioteca Nacional (the Portuguese National Library) just published a digital version of a map dated 1776 on the demarcation to the diamond mining region, whose center is Diamantina (the Arraial do Tejuco).
The map, bought in an auction held in 2011, may have been an annex of official correspondence between the Real Extracção (in Minas Gerais) and the Directoria dos Diamantes (in Lisbon).

Diamantina é uma das minhas cidades favoritas; perdi já a conta às visitas que fiz a esta jóia mineira e luso-brasileira. A cidade, a região e os seus diamantes e geologia são tema frequente de textos (aqui, aqui e aqui) e fotografias publicados neste blog (aqui, aqui e aqui – basta clicar para aceder aos textos e às galerias de fotos).
Localizada a norte de Belo Horizonte, esta cidade hoje Património Mundial, viu nascer Juscelino Kubistchek (Presidente da República e personagem central do século XX brasileiro) e Chica da Silva (a escrava-senhora, mítica personagem do século XVIII).
No primeiro quartel do século XVIII, Diamantina foi o local onde foram descobertos os primeiros diamantes no Brasil, os primeiros diamantes produzidos fora da Índia dando início a uma revolução no mercado desta pedra preciosa.
A Biblioteca Nacional publicou  a versão digital de um mapa datado de 1776 relativo à demarcação diamantina – delimitação da área onde se realizava a extracção de diamantes e em cujo centro se localizava o Arraial do Tejuco (Diamantina).

O mapa representa a demarcação da Região Diamantina, situada na comarca do Serro Frio, na Capitania de Mato Grosso (hoje Estado de Minas Gerais), no Brasil. O centro da demarcação era o Arraial do Tejuco, a actual Diamantina. Este mapa pode ter feito parte de um anexo da correspondência trocada entre a Real Extracção dos Diamantes, no Arraial do Tejuco, e a Directoria dos Diamantes, em Lisboa – in Biblioteca Digital Luso-Brasileira.

Este mapa, sem autor atribuído, foi adquirido pela Biblioteca Nacional de Portugal em Abril de 2011 num leilão organizado pelo Palácio do Correio Velho.

 

The source of diamonds in the Diamantina (Minas Gerais) region: Fm. Sopa – Brumadinho

Conglomerado Sopa (Sopa – Guida outcrop)

The precambrian Sopa Conglomerate is the source for modern alluvial diamonds deposits in the Diamantina (Minas Gerais) region. This old secondary formation is being reworked by the rivers in the area, releasing the diamonds it stores (themselves originated in primary, still unidentified, sources) into modern alluvia. Both the old conglomerate (Fm. Sopa – Brumadinho – Espinhaço Supergroup, Middle Proterozoic) and modern alluvia have been mined for diamonds since the early XVIII century in the region, in the process giving birth to diamond’s Modern Era.

Several outcrops may be visited in the area: the pictures I have included in the https://xmbl.wordpress.com/geology-rocks-formations-and-places/history-churches-diamonds-and-gold-in-minas-gerais-s-joao-del-rey-diamantina-2004/ photo gallery are from Lavrinha (Campo de Sopa – Guinda), a short travel from Diamantina. Many other outcrops are visible in the region.

You may also read the geological site description (in Portuguese, just an English abstract) in an article by Mário Chaves and Ítalo Meneghetti Filho available here: sitio036.

A mineral treasure trove in Goiás (GO) and Minas Gerais (MG) – BRAZIL

Serra do Espinhaço (Minas gerais - MG) - from Diamantina to Carvel, on the way to Belo Horizonte.
Serra do Espinhaço (Minas Gerais – MG) – from Diamantina to Curvelo, on the way to Belo Horizonte.

I have been in Goiás (GO) and Minas Gerais (MG) – Brazil in the last two weeks. It is a land of mineral opportunities – in a couple of days I visited manganese, iron, emerald, gold, nickel, diamond, aggregates and limestone deposits and prospects. It was the ideal road trip: looking for mineral deposits, in Brazil – my home away from home, with friends – old and new. Can you ask for more?

Curious? The photo gallery can be seen here.

Diamonds in the Chapada Diamantina – Bahia, Brazil

Just before starting a new trip to Brazil (into manganese mineral deposits in Goiás and Minas Gerais), this is a new photogallery for a 2004 road trip aimed at learning about the Bahia diamond deposits (geology, formation, history, social and natural settings). Of course, it was just the perfect pretext for four old friends getting into another Brazilian road trip. It took us from Diamantina (Minas Gerais) to Andaraí and Lencóis (Bahia).
I just hope the new trip’s photos won’t take 10 years to be published…
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Diamantina diamonds

The “My Precious” picture gallery grows (check it here), with more diamond photos from past trips to the Diamantina – Minas Gerais, Brazil.

Light conditions are always poor and time short. It helps to travel with friends they know but the garimpeiros, despite intrigued with the expensive camera laden gringo speaking funny Portuguese, are invariably friendly; they always let me take all the pictures I want and let me, a stranger, witness the negotiation process. This picture – a complete parcel, including its container – was taken in 2012 in the Diamantina – MG region.

The full diamond parcel, complete with container
The full diamond parcel, complete with container

 

Goldman Small Cap Research investment report on Brazil Minerals (gold and diamonds)

Brazil Minerals, Inc. (OTCQB: BMIX), a U.S. holding company with revenues from gold and diamonds, announced that Goldman Small Cap Research had issued an investment report on BMIX. The report can be accessed here (from our repository) or at Brazil Minerals’ website.

 

 

Not just diamonds – Jequitinhonha river gold

Gold dust from diamond-bearing gravels in the Jequitinhonha river (MG - Brazil)
Gold dust from diamond-bearing gravels in the Jequitinhonha river (MG – Brazil)

The old Tejuco settlement in Minas Gerais of the then Portuguese colony of Brazil was the birthplace of the modern diamond industry in the first quarter of the XVIII century. Until then diamonds originated in India and other minor localities in the East. After that, predominance in the diamond production changed into the South Atlantic (Brazil, Venezuela and elsewhere in South America, South Africa, Namibia, Angola, RDC, Botswana, Zimbabwe and elsewhere in west, southern and central Africa); the Indian Ocean no longer ruled diamond mining.

Diamonds are still produced in old Tejuco (now, appropriately) Diamantina region (I love the area and the country; you will see plenty of it in my posts). The Jequitinhonha river drains the region, its tributaries collecting diamonds released from the Sopa Brumadinho Formation (Espinhaço Supergroup) precambrian conglomerates in the Southern Espinhaço Range (article from a Mario Chaves and Italo Filho, here). The diamonds collected by the Jequitinhonha river are deposited along its margins (in terraces and alluvial plains) and in the bottom of the river.

The river has seen intense diamond mining activity since the XVIII century until our days (with Brazil Minerals’ Duas Barras project – to know more about this project, their webpage is here and you can get a copy of their 2007 NI43101 here). Perhaps the most active was the Tejucana project, (that saw its heyday during the period in which Sibeka from Belgium was the company’s main shareholder, until the early 90’s). Tejucana dredged diamonds and gold from the river bottom; in certain stretches gold production represented a major contribution to the total revenue.

The picture was taken a few years ago during one of my trips to the region. Usually I focus my camera on diamonds from the area (photo galleries).

But not just diamonds – the Jequitinhonha river also contains gold.

Zimbabwean diamonds in Brazil

Zimbabwean diamonds
Zimbabwean diamonds

Zimbabwean diamonds were in the news recently, with reports of their alluvial deposits – the base of their boom production in the last years – being close to exhaustion. These ones were photographed in Diamantina, Minas Gerais (Brazil), far from home.

They are not the prettiest thing, certainly not like the famed Angolan alluvial diamonds or for that matter the local Jequitinhonha river diamonds. There surely is an interesting story behind their voyage, though.

How have they got there? Where may have they gone since?

Diamonds from Diamantina – MG, Brazil

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A rare feature – hexagonal pitting

Diamonds occur in many colours, shapes, sizes and transparencies. Sometimes they just look like sand (well, expensive, very expensive sand, as a lowly 10 USD/carat stone is worth more than gold – currently hovering 1.200 USD/oz); or else diamonds may be broken (chips), dotted in the inside with other minerals, eroded or pitted at the surface, colourless, slightly tinted or, rarely, fancy (marked tints).

The rough diamonds in this parcel are from the Diamantina region (Jequitinhonha river) in Minas Gerais (Brazil). This is an historic diamond district, originally found and discovered in the early 17th century during Brazil’s colonial period. Diamonds in the area tend to have a greyish tint; alas, this is not their body color (as they would be extremely rare and expensive), just the color of a shallow coating probably due to radiation.

This photo illustrates a rare diamond feature caught by chance on camera. Note the focused diamond on the right hand side; it has a triangular shape (locally know has chapéu de frade). On the center of the diamond there is a depression of rare hexagonal shape, unlike trigons diamond’s characteristic inverted pyramidal pits.