First occurrence of kitagohaite, Pt₇Cu, from the Quadrilátero Ferrífero, Brazil

A kitagohaite grain, measuring approximately 1.0 mm, was retrieved from an alluvial gold gravity concentrate from the southeastern Quadrilátero Ferrífero (QFe), Mariana, Brazil. The grain exhibits a cubic structure, whitish-steel-gray, and has a metallic luster. It is composed of Wt. 94.42% Pt and 5.56% Cu (n=9), yielding the empirical formula Pt_6.78Cu_1.22. This groundbreaking discovery marks the first documented occurrence of kitagohaite in South America. This hydrothermal deposition of kitagohaite indicates that its mineralization is constrained to temperatures <500 deg C, as inferred by the stability of synthetic Pt₇Cu. (author)