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PETROGRAPHY OF THE PEGMATITES FROM RIO DAS MORTES VALLEY, SOUTHEAST MINAS GERAIS, BRAZIL

2018; Sociedade Brasileira de Geologia; Volume: 17; Issue: 4 Linguagem: Inglês

2177-4382

Joel Jean Gabriel Quéméneur,

Geological and Geochemical Analysis

The lithium-tin-tantalum bearing pegmatites of the Sao Joao del Rei region are characterized by various particularites: older age, probably Uruacuan, therefore they are older than most of the pegmatites of Minas Gerais; large size of bodies; unusual zoning: abnormaly high lithium content. These pegmatites are constitued by a granitoid core with more 25% of spodumene and an important aplitic border zone - the high lithium content may by explain a holmquistite - bearing contact metamorphism zone. Preliminary X-ray fluorescence data indicated a content of 1.3 to 2.4% of Rb in the potassium minerais. A crystallization model for the pegmatites is finally outlined.