|Location:||Rodrigo Silva, east of Ouro Prêto, Minas Gerais.|
|Light:||Incandescent Electric Light System|
Daniel A. Sauer, Alice S. Keller, Shane F. McClure (1996):
An Update on Imperial Topaz from the Capão Mine, Minas Gerais, Brazil,
GEMS & GEMOLOGY Winter 1996, pp. 232-241.
Peter Bancroft (1984): Imperial Topaz, In: Peter Bancroft, Gem and Crystal Treasures, Western Enterprises/Mineralogical Record, Fallbrook, CA, 488 pp.
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.
|1823||Ouro Prêto becomes capital of Minas Gerais.|
|1876||School of Mines established at Ouro Prêto.|
|1897||Belo Horizonte becomes new capital.|
Hydrothermal lodes contain quartz, hematite, magnetite, and accessory rutile, pyrite, and euclase. The enclosing rock was once schist, but it altered to a lateritic clay. This process is pretty fast in tropic climates, but despite it aggresivity it does not harm the resistant gemstones.
Capão Mine (Big Lid Mine) is the largest mine for imperial topaz in the world. It is an open cast mine, where weathered topaz-quartz-calcite veins are mined. The gravel is transported by a dredge bucket to the hydraulic washing station. The clay is removed with huge water cannons and the rocks in the material transported to sorting a belt, where the gems are sorted out by workers. The result of processing many tons of clay are a few dozen topaz crystals per day. Nevertheless, this mine is environment friendly as it does not use any chemical substances in the whole process.
Topas is mostly yellow, but it varies very much, and actually it appears in many colours. The topas mined here is the so called Imperial Topaz, which is reddish, sometimes also called peach. This area, about 20 square miles around Ouro Prêto, is the only relevant source of various coloured topazes in the world. The world's entire supply of imperial topaz is mined from two mines, the Vermelhao mine and the Capao mine. Some experts say the deposit will be exhausted very soon.
The mine is owned by Topázio Imperial Ltda. which is owned by Werner Colombarolli. It produces about 30% of the topaz produced in the region, and buys 40% to 50% of the production from the garimpeiros, fortune hunters who dig their own little claim. As a result Colombarolli has a sort of monopoly, which he used in 2007 to manipulate market. He thinks the peach-colored topas is sold undervalue, and so he bought as much as he could, thus reducing the supply and pushing the price.