DUMORTIERITE IN QUARTZ

High-clarity quartz sitting on top of and included by masses of fibrous, deep blue dumortierite. This specimen is in fantastic condition and the visible crystallization of the dumortierite makes for a great complement and an added element of intrigue.

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The Vaca Morta quarry in Minas Gerais, Brazil, demonstrates significant dumortierite-quartz mineralization occurring within metamorphosed pegmatitic bodies. The assemblage consists of dumortierite forming fibrous to columnar crystals in association with massive to crystalline quartz (SiO2), indicating high-temperature metamorphic conditions during formation. The mineralization process involved boron-rich fluids interacting with aluminosilicate precursor materials under conditions of regional metamorphism. This locality exhibits distinctive blue to violet dumortierite crystals penetrating clear to smoky quartz, producing specimens that beautifully demonstrate borosilicate mineral formation in metamorphic environments.