Ores and rocks specimens, Cuiaba deposit. Part I.
Tags: arsenopyrite bif pyrrhotite

Category: Ore
Deposit: Cuiaba
Description:A. Polished slab of non-mineralized Cuiabá BIF. The light quartz–carbonate bands (1) alternate with dark carbonate–quartz bands (2). The bands define the original compositional layering (Fonte Grande Sul orebody, level 5).
B. Marked banded texture in ores. light quartz–carbonate bands (1) and sulfide bands (3) (Serrotinho orebody, level 4).
C. Widespreadly recrystallization of pyrite over light and dark quartz carbonate layers (Balancão orebody, level 5).
D. Mineralized Cuiabá-BIF showing isoclinal folding of sulfide mesobands (Fonte Grande Sul orebody, level 5).
E. Sheared ore showing the boudinage of more competent quartz–carbonate, chert-rich layer. Sulfide is mostly pyrrhotite. Boudin neck areas are filled by quartz and sulfides (stope of Fonte Grande Sul orebody, level 5).
F. Large pyrite porphyroblast with inclusions of gold (Au), pyrrhotite (po), arsenopyrite (asp), and gangue minerals (quartz and carbonate, dark color) (Fonte Grande Sul orebody, level 5).