The Brazilian city of Ouro Preto, in the Minas Gerais state, has been established during the XVIIth century and flourished quickly thanks to gold mining. The most famous of them, exploited until the second part of the XXth century, is now partly visitable. This city very prosperous, as the numerous monuments and the architecture can testify. Besides, in 1876 the first School of Mines of the country was based by Claude Henri Gorceix at the request of Pedro II of Brazil.

Ouro Preto streets follow the hills

The township

The School of Mines, former governor's palace

Gold is beared in sulfides mineralizations of hydrothermal origin, in a black shists matrix (Ouro Preto means “black gold” in Portuguese). Un important shear zone has permitted the gold-charged fluids to circulate in those shists.

In the Passagem mine

Sulfides in quartz

Cars of the mine of Passagem

Nowadays, mining activity in the Ouro Preto region is still intense (iron, aluminium, manganese), but this locality is mostly known in the mineralogic world because of the imperial topazes which are extracted there.These topazes, very estimated sinces centuries, present an intense coloration from orange to pink.

Imperial topazes from Ouro Preto