Brazilian mica-bearing region

BRAZILIAN MICA-BEARING REGION (RU: Бразильский слюдоносный район) is the group of the deposits with muscovite within Brazil, within the eastern part of the Minas Gerais state. The region is being developed since the 1900. The Brazilian mica-bearing region (with the length of 600 kilometres, and with the width of 200 kilometres) is confined to the outcrop of the Archean rocks of the Brazilian shield. The most large deposits are the Governador Valadares and the Espera Feliz (50% of the extraction within the region).

The shape of the pegmatite bodies is: flat-lying lenses (the length along the strike is 300 metres, the length along the dip is 60 metres, the thickness is up to 20 metres); vertical tabular bodies (the length along the strike is more than 1000 metres, the length along the dip is 170 metres, the thickness is up to 50 metres). The structure of the veins is zonal, muscovite is situated both on the boundary with the quartzous core of the veins, and at the contact of the veins with the country rocks. The content of the large-crystalline raw muscovite is 25 kilograms per cubic metre on average. The reserves of the mica are 5-10 million tonnes. The yield of the sheet mica from the raw material is 16%. Along the way, they extract beryl, columbite, tantalite. At the 15 industrial pegmatite fields, there may be counted several hundreds enterprises. The deposits are being developed by the open pit mines (the depth is up to 60-70 metres), and by the underground mines (the depth is up to 175 metres). The extraction is 400 tonnes of the raw muscovite, 100 tonnes of the sheet mica (1981). Such sharp decrease for the extraction of mica (from 2.8 thousand tonnes of the raw muscovite and 450 tonnes of the sheet mica during the 1978) is associated with the worsening of its quality. The mica is exported mainly into the USA.