DIAMANTE Você sabe qual é a diferença entre diamante e brilhante?

DIAMANTE

DIAMANTE

Você sabe qual é a diferença entre diamante e brilhante?

Do lado esquerdo da tela, diamante. No centro, selo emitido pela Alemanha Ocidental em 1997 (Yvert: 1743). Do lado direito, brilhante em foto da Joalheria H. Stern.
Diamante é o nome da pedra preciosa em estado bruto ou já lapidada. O brilhante, por sua vez, é um dos muitos tipos de lapidação que existem para o diamante.
A lapidação do tipo brilhante foi criada em 1919, por Marcel Tolkowsky, e possui forma redonda, com 57 ou 58 facetas. É uma das lapidações que conferem mais brilho e beleza ao diamante. É tão conhecida que seu nome acabou se tornando um sinônimo popular de diamante.
O diamante é composto apenas de carbono puro cristalizado. D: 10. DR.: 3,5.
Tem brilho adamantino, transparente a opaco, incolor, podem ser brancos, azulados ou até cor de chocolate, com diferentes tamanhos, formatos e técnicas de lapidação. Às vezes, amarelado, raramente verde, azul, vermelho e negro. Não é riscável por outras gemas, fratura concóide, clivagem perfeita.
Encontra-se em antigas rochas vulcânicas e em placers. Utiliza-se lapidado no talhe brilhante – que é o símbolo do amor eterno... representa luxo, brilho e resistência.
A primeira mulher da história a receber, como presente de noivado, um anel de diamantes foi Mary de Burgundye, em 1477. Conta a história que o Arqueduque Maximiliano, da Áustria, consultou um dos seus assessores quando se preparava para pedir a mão de Mary em casamento.
O assessor sugeriu que o noivo oferecesse um anel de diamante e uma aliança de ouro. O Arqueduque seguiu o conselho e, ao fazer o pedido, colocou o anel com diamante no terceiro dedo da mão esquerda de Maria...

Foto da Joalheria H. Stern.

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A história dos diamantes, porém, é bem mais antiga. Nos últimos 2.500 anos eles vêm sendo utilizados em joias e adereços. O termo “diamante” é derivado da palavra grega “Adamas” (o inconquistável), prova suficiente de que, já na Antiguidade, era conhecida e apreciada por sua indestrutível beleza.
Os gregos se referiam aos diamantes como faíscas das estrelas que caíam sobre a Terra. Sobre eles, dizia-se também que o fogo refletido era a constante chama do amor. E mais: eles seriam lágrimas dos deuses.
A natureza comprova o quanto essas gemas são especiais... O diamante é a única pedra preciosa composta apenas de um elemento, o carbono. É exatamente a mesma composição do grafite, que parece seu antônimo: sem brilho, cinzento, quebradiço.
Quem pensaria em colocar uma pedra de grafite em um anel de noivado?
A explicação, mais uma vez, vem da natureza. Embora diamante e grafite sejam compostos do mesmo elemento, a forma como os átomos de carbono se unem uns aos outros é completamente diferente.
A isso chamamos de alotropia, do grego allos (outro) e tropos (maneira), é o fenômeno que consiste em um elemento químico poder existir estavelmente sob formas diferentes, com diferentes propriedades físicas e químicas. Exemplo: grafita (grafite) e diamante.
Até o século XVII, quase todos os diamantes comercializados no mundo tinham como origem a mina de Golconda, na Índia. Daquele local foram extraídos alguns dos mais famosos diamantes do mundo, como o Koh-i-Noor, que faz parte das joias da coroa da Inglaterra, e Orloff, patrimônio das joias da coroa da Rússia.
Mas, em 1725, o Brasil quebrou esta tradição, após a descoberta de diamantes na cidade de Diamantina, em Minas Gerais. Durante os 150 anos seguintes, o estado seria alçado à posição de maior produtor mundial de diamantes, perdendo esta posição, mais tarde, para a África do Sul.
Apenas 20% dos diamantes são utilizados para joalheria. O restante é aproveitado na área industrial. O diamante é muito resistente e utilizado, por exemplo, nos equipamentos de perfuração de petróleo e para o corte de vidro. O diamante é tão resistente que somente um diamante corta outro diamante.
O maior diamante foi encontrado na África do Sul, em 1905, e tinha 3106 quilates, que deu origem a 105 pedras de menor tamanho. Dentre elas está o diamante Cullinan I (também chamado de “Estrela da África”), com 530,20 quilates que adorna o cetro do Rei Eduardo VII; hoje localizado na Torre de Londres.
Localidades: Brasil, África do Sul, Congo, Angola, Tanzânia, Austrália, Federação Russa. Atualmente existem minas de diamantes nos estados de Minas Gerais, Mato Grosso, Bahia, Maranhão, Piauí, Pará, Paraná e Roraima.
Analogias: Energia: projetiva. Planeta: Sol. Elemento: fogo. Signo: Áries, Leão. Chakra: todos. Tarô: A Justiça.
Fortalece funções cerebrais, ajuda o alinhamento dos ossos do crânio. Quebra bloqueios no chakra coronário e na personalidade, é um grande curador.
Afasta a negatividade, purifica o corpo físico e etéreo. Reflete os aspectos divinos de vontade e poder. Purifica e limpa sexualmente. Aumenta a força física e dá coragem.
É a mais neutra de todas as gemas e é extremamente poderosa para remover bloqueios, negatividade e disfunções sexuais. O Diamante intensifica a energia de outras pedras, promove a clareza do pensamento, amplia o pensamento, nos aproxima do Eu superior.
Em essência, é para trabalhar as partes espirituais mais elevadas do ser dentro do corpo físico.
Objetivos: espiritualidade, grande curador, paz, coragem, vigor. Protege contra os inimigos.
Diamante é uma pedra incolor, considerada a mais resistente que existe. Por isso atribui-se a ela o significado de solidez, durabilidade e pureza.
Diamante vermelho é a pedra das grandes paixões...

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Curiosidades

Filatélica:
Na internet é possível ver parte de uma coleção de Selos Postais sobre Diamantes, Diamonds on Postage Stamps (www.diamondstamps.eu). Parece que o colecionador é um italiano que vive na Croácia...
Museológicas:
– Museu do Diamante (Iphan). O Museu do Diamante está localizado no centro da cidade de Diamantina (www.diamantina.mg.gov.br), no Estado de Minas Gerais (MG), possui objetos da época colonial, como móveis, utensílios, instrumentos utilizados para prender e castigar os escravos e para extrair ouro e diamante. O Museu do Diamante foi criado em 12/04/1954 e está abrigado em um dos prédios de maior significado histórico de Diamantina, construído no século XVIII. Além de ocupar casa de grande importância histórica e arquitetônica, o Museu do Diamante detém acervo que constitui um significativo centro de memória da região de Diamantina. Este acervo representa objetos relativos à extração diamantífera e o contexto social da região mineradora dos séculos XVIII e XIX, reunindo ainda arte sacra, mobiliário, armaria, transporte, indumentária e outros objetos. Destacam-se, neste acervo, as pedras preciosas e semipreciosas, as balanças de pesagem de ouro e diamante, os oratórios característicos da região. Todo este acervo propicia uma visão abrangente da histórica região Diamantina.
– O Museu do Diamante de Amsterdã, Diamond Museum Amsterdam (www.diamantmuseumamsterdam.nl), está localizado na capital da Holanda. O sítio oferece um Virtual Tour que vale a pena conferir!

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HISTÓRIA DO DIAMANTE HOPE

De todos os diamantes conhecidos, a pior fama é do Hope, o Diamante Azul, que a lenda o rebatizou como “A pedra que mata”. Segundo a lenda, ele se encontrava na frente de uma importante estátua de Budha quando foi roubado por um guerreiro, que pouco depois foi assassinado.
Depois disso um comerciante vendeu a pedra para o Rei Luis XIV. Pouco depois o comerciante empobreceu, contraiu uma doença e morreu em meio a terríveis convulsões.
Quando a Madame de Monespan, obteve a honra de provar o diamante, foi abandonada e morreu sozinha na pobreza...
Depois da Revolução Francesa, o diamante foi escondido em edifício Guarda-Móveis Nacional, de onde foi roubado em 1791. Seis anos depois, os ladrões foram condenados à pena de morte.
Em 1830 o Hope foi comprado em um leilão por 90.000 libras esterlinas, por Francis Hope, membro do parlamento, que morreu logo depois, de mal súbito. Posteriormente, sua viúva morreu queimada na mansão.
Seu herdeiro e sobrinho Thomas, pouco tempo depois de receber a pedra, foi a falência nos negócios e abandonado pela esposa. Thomas se desfez do diamante, que foi comprado pelo príncipe russo Iva Kitanovski, para presenteá-lo a uma bailarina que, na noite que o usou pela primeira vez, foi assassinada com um tiro.
Após uma série de tragédias, a pedra ficou com o sultão Abdul Mamid II, ao se ver forçado a abdicar a favor de seu irmão, levando o Hope entre seus pertences para o exílio.
No início do século adquiriu-o a família Mac Lean, pouco depois, um de seus filhos se suicidou e outro morreu em acidente de automóvel. Mac Lean caiu em depressão, e morreu meses depois em uma clínica para doentes mentais.
O diamante Hope se encontra atualmente no Smithsonian Institute de Washington, onde seu fluxo magnético não transpassa o grosso cristal da vitrine onde é exposto aos turistas...

ALEXANDRITA

ALEXANDRITA

A mais rara e valiosa variedade de crisoberilo exibe as cores verde e vermelha, as mesmas da Rússia Imperial, e seu nome é uma homenagem a Alexandre Nicolaivich, que mais tarde se tornaria o czar Alexandre II; de acordo com relatos históricos, a sua descoberta, nos Montes Urais, em 1830, deu-se no dia em que ele atingiu a maioridade. Como uma das mais cobiçadas gemas, esta cerca-se de algumas lendas, a mais difundida das quais diz que o referido czar teria ordenado a execução de um lapidário, depois que este lhe devolveu uma pedra de diferente cor da que lhe houvera sido confiada para lapidar. Esta lenda deve-se ao fato de que a alexandrita apresenta um peculiar fenômeno óptico de mudança de cor, exibindo uma coloração verde a verde-azulada (apropriadamente denominada “pavão” pelos garimpeiros brasileiros) sob luz natural ou fluorescente e vermelha-púrpura, semelhante a da framboesa, sob luz incandescente. Quanto mais acentuado for este cambio de cor, mais valorizado é o exemplar, embora, para alguns, os elevados valores que esta gema pode alcançar devam-se mais a sua extrema raridade que propriamente à sua beleza intrínseca. Esta instigante mudança de cor deve-se ao fato de que a transmissão da luz nas regiões do vermelho e verde-azul do espectro visível é praticamente a mesma nesta gema, de modo que qualquer cambio na natureza da luz incidente altera este equilíbrio em favor de uma delas. Assim sendo, a luz diurna ou fluorescente, mais rica em azul, tende a desviar o equilíbrio para a região azul-verde do espectro, de modo que a pedra aparece verde, enquanto a luz incandescente, mais rica em vermelho, faz com que a pedra adote esta cor. Este exuberante fenômeno é denominado efeito-alexandrita e outras gemas podem apresentá-lo, entre elas a safira, algumas granadas e o espinélio. É importante salientar a diferença entre esta propriedade e a observada em gemas de pleocroísmo intenso, como a andaluzita (e a própria alexandrita), que exibem distintas cores ou tons, de acordo com a direção em que são observadas e não segundo o tipo de iluminação a qual estão expostas. Analogamente ao crisoberilo, a alexandrita constitui-se de óxido de berílio e alumínio, deve sua cor a traços de cromo, ferro e vanádio e, em raros casos, pode apresentar o soberbo efeito olho-de-gato, explicado detalhadamente no artigo anterior, no qual abordamos o tema do crisoberilo. As principais inclusões encontradas na alexandrita são os tubos de crescimento finos, de forma acicular, as inclusões minerais (micas, sobretudo a biotita, actinolita acicular, quartzo, apatita e fluorita) e as fluidas (bifásicas e trifásicas). Os planos de geminação com aspecto de degraus são também importantes características internas observadas nas alexandritas. Atualmente, os principais países produtores desta fascinante gema são Sri Lanka (Ratnapura e diversas outras ocorrências), Brasil, Tanzânia (Tunduru), Madagascar (Ilakaka) e Índia (Orissa e Andhra Pradesh). No Brasil, a alexandrita ocorre associada a minerais de berílio, em depósitos secundários, formados pela erosão, transporte e sedimentação de materiais provenientes de jazimentos primários, principalmente pegmatitos graníticos. Ela é conhecida em nosso país pelo menos desde 1932 e acredita-se que o primeiro espécime foi encontrado em uma localidade próxima a Araçuaí, Minas Gerais. Atualmente, as ocorrências brasileiras mais significativas localizam-se nos estados de Minas Gerais (Antônio Dias/Hematita, Malacacheta/Córrego do Fogo, Santa Maria do Itabira e Esmeralda de Ferros), Bahia (Carnaíba) e Goiás (Porangatú e Uruaçú). A alexandrita é sintetizada desde 1973, por diversos fabricantes do Japão, Rússia, Estados Unidos e outros países, que utilizam diferentes métodos, tais como os de Fluxo, Czochralski e Float-Zoning, inclusive na obtenção de espécimes com o raro efeito olho-de-gato. A distinção entre as alexandritas naturais e sintéticas é feita com base no exame das inclusões e estruturas ao microscópio e, como ensaio complementar, na averiguação da fluorescência à luz ultravioleta, usualmente mais intensa nos exemplares sintéticos, devido à ausência de ferro, que inibe esta propriedade na maior parte das alexandritas naturais. Na prática, a distinção por microscopia é bastante difícil, seja pela ausência de inclusões ou pela presença de inclusões de diferente natureza, porém muito semelhantes, o que, em alguns casos, requer ensaios analíticos mais avançados, não disponíveis em laboratórios gemológicos standard. O custo das alexandritas sintéticas é relativamente alto - mas muito inferior ao das naturais de igual qualidade - pois os processos de síntese são complexos e os materiais empregados caros. O substituto da alexandrita encontrado com mais frequência no mercado brasileiro é um coríndon sintético “dopado” com traços de vanádio, que também exibe o câmbio de cor segundo a fonte de iluminação sob a qual se observa o exemplar. Eventualmente, encontram-se, ainda, espinélios sintéticos com mudança de cor algo semelhante à das alexandritas.

Expedition to the Cruzeiro Tourmaline Mine in Minas Gerais, Brazil

This handful of crystals is just a small portion of the production we saw during our short visit to the Cruzeiro mine. These multicolored crystals range from rubellite to green, with black terminations. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

In April 2014, a team from GIA visited major emerald and tourmaline sources in Brazil. One of the most exciting mines the team visited was the Cruzeiro tourmaline mine in the state of Minas Gerais, about two hours outside the city of Governador Valadares.

Mining for Tourmaline in Brazil
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Although the authors had been to many gemstone mines, the size of the mine’s gem-bearing pegmatites and veins and the quantity of tourmaline being produced made this one of the most prolific gemstone mines visited by GIA. You don’t often get a chance to see large, impressive crystals being constantly hauled out of a mine tunnel, with walls and pockets mined with picks and by hand. The tourmaline crystals seemed to be just laying embedded in the enormous pegmatites, waiting to be removed.

The Cruzeiro tourmaline mine is blessed with magnificent surroundings. Its owners work the mine in harmony with nature. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

The other visually striking aspect of this mine was the beauty of the setting and surroundings. The Cruzeiro mine is on a mountain, with a lush green landscape lining the road leading up to it. The mine location itself offers a spectacular view of hills, mountains, sky, and greenery.

History

The history of the Cruzeiro mine is intertwined with the rich mineral composition of the area, tourmalines mistaken for emeralds, mica mined for war efforts, unwavering belief in the richness of the deposit, tragedy, family unity, perseverance, and triumph.

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The Cruzeiro mine is located about two hours outside of Governador Valadares in the State of Minas Gerais, Brazil.

An Area Rich in Minerals

As far back as the mid-sixteenth century, the Portuguese were searching for emeralds. They thought they had discovered them in Brazil, but what the so-called bandeirantes had actually found was green tourmaline. During the seventeenth century, a Portuguese explorer documented the gemstones found in the area where the Cruzeiro mine is now located.

By the 1800s, the government’s will was strong to discover more of Brazil’s mineral wealth, including gold and precious stone deposits. When explorations in the Minas Gerais area revealed the presence of green tourmalines, explorers again initially thought they were emeralds. This belief led to much interest in further exploration of the area.

The actual mine deposit in the Cruzeiro area is said to have been discovered in 1915, and the first mining lease was established in 1938. In the 1940s, the US government was greatly interested in exploiting the mica deposits of the area for the war effort. The American company mining the mica employed 800 men, producing an estimated twenty percent of global mica production. The closest significant city, Governador Valadares, experienced significant economic growth during the mica mining period.

Today, mica is used in a decorative display at the Cruzeiro mine. In the war-time 1940s, it was of major strategic importance. Photo by Duncan Pay/GIA, courtesy Cruzeiro mine.

Mining for tourmaline began in the 1950s when Jose Neves and his brother Antonio De Assis Neves started what is now the Cruzeiro tourmaline mine. The brothers had been mining mica in the area and taking it to Governador Valadares to sell. They also bought and sold the production of other mica miners.

Interest in Tourmaline Increases

As the market for mica softened, the brothers started mining and selling tourmalines. At first they were only interested in large, clean tourmaline crystals. As a result, much of the production that was disposed of in waste piles might contain useable material today. The brothers also began cutting and selling tourmalines, as they were interested in moving farther up the value chain.

Not long after they became tourmaline dealers, they caught the interest of Julius Sauer of the world-famous Amsterdam Sauer gemstone and jewelry company. Mr. Sauer bought a large portion of the mine’s tourmaline production, then also bought the mine. Mr. Sauer worked the mine for about 15 years during the late 1960s through early 1980s. He then offered it for sale to Jose Neves, who was working for Mr. Sauer, buying tourmaline in the area and in Teofilo Otoni. Jose Neves sold everything he owned and invited his brother Antonio De Assis Neves to partner with him in the mine, which they purchased in 1982.

While the mine is rich in minerals, tourmaline is the main focus and its most commercially
important product. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

At the time, Julius Sauer advised Jose Neves not to take too many risks, as gemstone mining is a very uncertain business, and you never know for sure what you are going to get. But Jose Neves believed strongly that this would be an extremely rich mine and pursued mining it with all the energy and resources he could muster. One month after the warning by Mr. Sauer, Jose Neves hit a big deposit of pink tourmaline. Soon afterward, the mine began producing large amounts of red and pink, green, blue, and bicolor tourmaline, including 26 kilos of very clean rubellite.

Tragedy, Perseverance, and Success

The family suffered a tremendous tragedy in January 1992, when both Neves brothers died in a plane crash in Brazil. At that time Beatrice Neves, the wife of Antonio De Assis Neves, her son Antonio de Neves Jr., and Douglas Williams Neves, the son of Jose Neves, took over the mine. Douglas was a teenager at the time, but had already spent a considerable amount of time at the mine with his father, where he would mine for tourmaline using a pick. He’d then wash and clean the stones he found and sell them directly to his father.

Adding to the event’s tragedy, Douglas’s mother and another aunt also died in the plane crash. Even at that young age, Douglas stepped up and took over running the business with his Aunt Beatrice and her son Antonio. In running the business, Douglas built upon what he learned from his father and followed his own instincts and intuition.

The Cruzeiro mine is truly a family business. It owes its success to the close ties of the Neves family and their will to overcome tremendous tragedy. Photo by Duncan Pay/GIA, courtesy Cruzeiro mine.

Discovery, Tragedy, and Triumph
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The mining operation today is very successful, with 150 employees. One hundred of them are miners, and the mine has produced an annual average of more than eight tons of tourmaline over the last five years. This was only possible because these resilient family members came together as a team. Along with the loyal employees of the mine, they came through their tragedy and built one of the most successful colored gemstone mining operations in the entire world.

Regional and Local Geology of the Cruzeiro Mine

Cruzeiro is one of the world’s most important sources for gem and mineral specimens. The main mining area is located in the Safira pegmatite district within the Eastern Brazilian pegmatite province (EBPP). EBPP is one of three important pegmatite provinces, mainly situated in the state of Minas Gerais. The southern part of the state of Bahia and the western margin of the state of Rio de Janeiro are also part of EBPP. There are thousands of gem-bearing pegmatites in Minas Gerais, and they contain virtually every known pegmatitic gem mineral species.

Neoproterozoic collisions (~1000 to 540 million years ago) led to the final formation of the West Gondwana supercontinent and created the Brazilian orogens of South America and the Pan-African orogens of Africa. Orogens are formations resulting from large-scale continental collisions. Numerous economically important gem deposits have been discovered and mined along these so-called orogenic belts.

In South America, the São Francisco craton (an old and stable part of a continent), which forms eastern Brazil, is surrounded by a sequence of Brazilian orogenic belts. One of them is the Araçuaí belt, featuring west to northwest-extending thrusts and folds. The Araçuaí belt borders the eastern margin of the São Francisco craton and overlaps with EBPP.

During the post-collision stage (530 to 480 million years ago), bodies of intrusive igneous rocks, called plutons, penetrated the metamorphic rocks of the Araçuaí belt. One of these plutonic rocks is considered the source of many pegmatites containing gem tourmaline, spodumene, morganite, and other gems, plus industrial feldspar and muscovite. Although it is quite common to find large batholiths—emplacements of plutonic rock—in the immediate vicinity of gem-bearing pegmatites, in some areas the plutonic source rocks are not well exposed.

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This schematic geological map of the Araçuaí and Governador Valadares regions shows the location of the Cruzeiro pegmatites. – Modified after Viana et al., 2007, Chemical zoning of muscovite megacrystal from Brazilian Pegmatite Province; and Federico et al., 1998, Compositional variation of tourmaline in the granitic pegmatite dykes of the Cruzeiro mine, Minas Gerais, Brazil

The current Cruzeiro main mining area consists of four parallel, largely unweathered granitic pegmatite bodies, identified as pegmatites 01, 02, 03, and 04, and another pegmatite between 01 and 02, identified as pegmatite 01½. There are many other pegmatite outcrops on this property, but the major operation is focused on these four veins. All four pegmatite bodies dip steeply to the southwest and intrude into quartzite (metamorphosed sandstone).

In the Cruzeiro mine area, the contacts between the pegmatite bodies and the host
quartzite are all sharply defined. The white clay minerals that define the pegmatites are
the products of weathered feldspars, which are more vulnerable to weathering than
quartzite. Below the surface, the width of the pegmatite can be quite different from the
width seen in this partially exposed pegmatite body. Photo by Andy Lucas/GIA, courtesy
Cruzeiro mine.

The contacts between the pegmatite bodies and the host quartzite are sharply defined. Pegmatite 01 is 1300 meters long and up to 60 m wide. Pegmatite 02 is 900 m long and about 20 m wide. Pegmatite 03 is about 700 m long, with a maximum outcrop width of 8 m. There are no exact dimensions of pegmatite 04 currently available. The maximum width of pegmatite 01½ is so far thought to be about 30 m.

Whitish albite, purple lepidolite, and the yellowish to brownish iron-manganese coatings
are indicators that lead miners to gem-quality tourmalines. A good quantity of nice
rubellite crystals was recovered from the pocket in the upper left of this photo. Photo
by Andy Lucas/GIA, courtesy Cruzeiro mine.

These pegmatitic veins have very similar internal zoning, symmetrically distributed around a quartz core. The zoning contains a very thin border zone, a muscovite-quartz-feldspar wall zone and a quartz-microcline-albite intermediate zone, where the economically important gemstones are found. In the Cruzeiro mine, gem-quality tourmaline is usually found right next to the quartz core and associated with albite rather than microcline feldspar. Massive non-gem garnet is also found in this mine.

The Pegmatites
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The Thrill of Discovery

Speaking with unbridled enthusiasm, Douglas Neves and his Aunt Beatrice described for us the thrill of discovering major tourmaline pockets and crystals. They are ready to come to the mine at a moment’s notice 24 hours a day, and even though they have experienced such moments thousands of times, they feel the same sense of excitement, like a kid receiving his best present, or a parent giving birth to a child. Their first reaction is a desire to keep the tourmaline and never sell it, but the reality is that they must sell their stones to keep the business going. If an important pocket is found, they may work all night to remove the tourmaline crystals, which have become more and more valuable over the last several years, due primarily to the enormous demand in China.

For Beatrice and the other family members, the thrill of discovering tourmaline is as strong today as it ever was. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

Treasure Hunters
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Production

Of the eight tons of annual production, approximately 70 percent is carving and bead quality, 10 percent is clean facet grade, 10 percent is cabochon grade, and 10 percent is suitable for specimens. The Cruzeiro mine produces all tourmaline colors. Douglas estimates that green makes up the largest percentage of total production. Pink and rubellite colors make up about 30 percent, and blue about 10 percent. These color percentages are difficult to estimate because many of the crystals are bicolored or multicolored, with crystals commonly going from pink or rubellite colors to green, and terminating in black. The black tourmaline is often highly fractured and sold for industrial uses.

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Mining Tourmaline

Visiting the Mine

The mine is about 36 miles northwest of Governador Valadares and about six miles from the town of São José da Safira. The latter is named after sapphire, probably due to blue tourmalines found and mistaken for sapphires by early explorers. We drove to the top of the mountain Serra Resplendecente do Cruzeiro, where the mine is located at 4,593 feet. The mine and a small nearby village are both named Cruzeiro, meaning cross due to the presence of a local church.

The Cruzeiro mine has an extensive array of horizontal mining tunnels, called galleries, located at different depths. Some of the galleries are very long: One extends to 500 meters. This mine’s pegmatites are enormous. At the deepest mining area, the pegmatite is 32 meters wide and over one kilometer in length. The property itself is close to 3,000 hectares (a hectare is equal to 2.471 acres). The area that is actually being mined is only around 100 hectares, but much of the rest of the property shows promise for successful future production.

Navigating the mine involved descending to different depths on vertical to near-vertical
ladders, and then following horizontal galleries. Photo by Andrew Lucas/GIA, courtesy
Cruzeiro mine.

Beatrice proved to be far more able to navigate the mine with less effort than any of our
GIA team. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

Pegmatite 01½ has its name because they discovered it while attempting to tunnel into vein number 01 from a different direction. They soon realized they were in a new vein that connected with veins 01 and 02. Vein 01½ is currently their most productive vein. They refer to it as Umbezão, which means “the big one.”

The Mining Operation

In 1996, the mining operation was re-structured to incorporate modern mining methods. Currently, Cruzeiro is working three veins. The current mining plan includes a new entrance and new ramp as well as further assessment of all the pegmatites. They evaluate a pegmatite by looking at its central quartz core zone, where they find green tourmaline at the side contact areas. Next to the green zones are pink and rubellite colors, and then mica. Drilling near the quartz core veins, they look for lines of black tourmaline and indicator minerals of lithium, lepidolite, albite, and mica. Besides tourmaline, they also find colorless, white, and rose quartz, aquamarine, morganite, and red garnets. However, tourmaline is the focus as it’s the most economically important gemstone mined here.

These tourmaline crystals are attached to a section of the quartz core vein. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

In some areas of the mine, the tourmalines are scattered throughout the walls of the pegmatites in a pattern they call staining. In other areas, the tourmaline crystals are in pockets, some of them massive. The crystals are extracted from the walls and pockets with a pick, often followed just by hand tools.

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The Cruzerio Production

Inside the Mine
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The processing stage is simple and uses classic methods. The rough is washed by hand in wire baskets submerged in large drums of water. Manipulating the baskets in a circular motion allows the water to wash away the smaller pieces of lighter overburden, leaving larger crystals behind. While we watched, several large tourmaline crystals were recovered. Many of them were multicolored, with red-to-pink rubellite transitioning to green, and with black terminations. Some of the crystals were quite large. There were also large blue and green crystals. After washing, the crystals were cleaned further and some were rolled in newspaper for protection, a common technique that’s used especially for specimens.

While the washing equipment and procedures were very basic, they accomplished the task of removing the overburden, leaving behind the easily seen tourmaline crystals. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

Describing the Mine
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The Business Model

The mine owners are rejoicing at the current demand for tourmaline in the global market. The mine produces all colors of tourmaline, so they can take advantage of the fact that all colors are in demand. Demand is especially strong for rubellite and bicolor varieties, with strong demand for greens, followed by blues. One of the main tourmaline consuming countries is China. This has been especially true with rubellite and now is also true for bicolors, greens, and blues.

These faceted rubellites were cut at the Miranda Group Co. Ltd. factory in Shenzhen, China. They are being sorted in the Group’s Hong Kong office. The rough came from the Cruzeiro mine. Photo by Andrew Lucas/GIA, courtesy Miranda Group Co. Ltd.

The Cruzeiro mine works with Miranda Group Co. Ltd., which cuts their rubellite tourmaline and markets it through KGK, a global diamond, colored stone, and jewelry wholesaler. KGK markets the majority of the rubellite in China. The Miranda Group saws the rough at their Hong Kong office and then sends the sawn rough for finishing at their factory in Shenzhen. KGK then handles the sale of the finished rubellites. The company also sells rubellite jewelry in China.

The Miranda Group Co. Ltd. cuts the rubellite from the Cruzeiro mine at their factory in Shenzhen, China. Photo by Andrew Lucas/GIA, courtesy Miranda Group Co. Ltd.

The majority of Cruzeiro production goes to China. Cruzeiro itself cuts the green and blue facet-grade material in Governador Valadares and sells the finished stones in the wholesale market. Cruzeiro sells carving, bead, and cabochon-grade rough into the China market for manufacturing.

Describing the changes in the price of tourmaline over the last five years, Douglas says, “When I think about the prices I sold tourmaline for five years ago, I did not sell it, I gave it away.” Five years ago it would have been difficult to get $1,000 a kilo for carving and bead-grade rough tourmaline, while today he can easily get $7,000 a kilo. Facet-grade green tourmaline that was selling for ten to twenty dollars a gram five years ago, now sells for $150 a gram.

All colors and grades of tourmaline have risen significantly in demand and price. This is especially true for large, clean, fine-color rubellite. Photo by Andrew Lucas/GIA, courtesy Miranda Group Co. Ltd.

These increases in the selling price are offset by increased production costs. Costs of labor, fuel, equipment, environmental regulations, etc., have risen significantly over the last five years. Also, the value of the Brazilian currency—the Real—has risen significantly against the dollar. This was difficult for the entire Brazilian gemstone and jewelry industry since their costs are in Reals and their sales on the international market are in dollars. This reversed a bit in the last two years, with the Real going from approximately 1.5 to 1 dollar in value. During our visit, there was a drop in value to 2.4 Reals to the dollar. The massive production from the Cruzeiro mine also helps it to compensate for increasing production costs.

While the price of and demand for tourmaline has been rising, mining costs in Brazil have also been going up. Photo by Andrew Lucas/GIA, courtesy Cruzeiro mine.

The Market
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Business Costs
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The Environment
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The Future

When describing the mine’s future, Douglas informed us that they are planning to turn it into a ramp-style mine. The ramp will start at the surface and cut across all five main pegmatite veins currently being mined, plus one more they are planning on mining. Shafts will extend upward from the ramp so they can bring the material down to the ramp and haul it out by truck.

With over 95 percent of the property not being mined and large areas showing strong production potential, the future yield of the mine looks strong. Douglas told us that his father always said that his grandchildren would be mining tourmaline at Cruzeiro.

About the Authors

Andrew Lucas is manager of field gemology at GIA in Carlsbad, California. Duncan Pay is editor-in-chief of Gems & Gemology and director of content strategy at GIA in Carlsbad. Tao Hsu is technical editor of Gems & Gemology. Shane McClure is director of West Coast identification at GIA's Carlsbad laboratory. Pedro Padua is the video producer at GIA in Carlsbad.

DISCLAIMER

GIA staff often visit mines, manufacturers, retailers and others in the gem and jewelry industry for research purposes and to gain insight into the marketplace. GIA appreciates the access and information provided during these visits. These visits and any resulting articles or publications should not be taken or used as an endorsement.

Chrysoberyl and Alexandrite from the Pegmatite Districts of Minas Gerais, Brazil

This fourth article in the author's series on the pegmatite districts of Minas Gerais, Brazil, focuses on chrysoberyl, particularly the rare but coveted varieties cat's-eye and alexandrite. Most of the cat’s-eye chrysoberyls on the gem market today come from Brazil, primarily from the region around the Americana and Santana valleys. This article examines some of the more important mines in this region, with a detailed description of the Barro Preto deposit. Farther south, the Malacacheta area has produced a number of fine alexandrites during the last 13 years. Since October 1986, however, it has been overshadowed in both quality and quantity by the small Lavra de Hematita, which produced 50 kg of fine alexandrite in less than three months. These two occurrences are also described in detail.                                        

The Indaia Sapphire Deposits of Minas Gerais, Brazil

The discovery of significant quantities of gem-quality sapphire in Minas Gerais could add corundum to the formidable list of gem species already commercially produced in Brazil. The presence of sapphire has been confirmed over a wide area within a 42-km² mining claim, and exploration has yielded over 500 ct of corundum per square meter from alluvium in a small section of the claim. Faceting-quality stones typically range from 0.5 to 2ct; some are purple or violet, and many show a color change. Future production will depend primarily on the results of ongoing exploration and the feasibility of mechanizing an area of difficult access.