São Sebastião is a recently discovered gold deposit in the Pitangui greenstone belt, Minas Gerais, Brazil. Part of its hydrothermal system is characterized by chaotically distributed tourmaline that is concentrated in patchy domains, or pockets. The tourmaline-rich pockets obliterate the foliation of the host greenstones. Pyrrhotite and late chalcopyrite occur in the tourmaline-rich pockets. Bismuth, bismuth–gold intermetallic aggregates, and Bi-telluride minerals locally fill microfractures that are superimposed on preexisting, chalcopyrite-bearing microfractures in the tourmaline-rich pockets. Hedleyite (Bi7Te3) as well as the unnamed minerals Bi8Te3 and Bi2Te are noteworthy. Specifically, hedleyite and Bi8Te3 make up composite aggregates with joséite-B (Bi4Te2S) in which the Bi8Te3 is unambiguously distinguished from hedleyite, both optically and compositionally. The Au–Bi–Te mineral assemblages indicate precipitation below about 270 °C, under epizonal conditions, in a mesothermal (orogenic) setting. Comparison with the economically and historically important Passagem de Mariana gold mine shows similarities that are indicative of a possible widespread, but still poorly recognized, epizonal overprint in Minas Gerais.
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Research Article|
November 01, 2015
Empirical Bi8Te3 and Bi2Te from the SÃo SebastiÃo Gold Deposit, Brazil: Implications For Lode-gold Mineralization in Minas Gerais
Alexandre Raphael Cabral;
Alexandre Raphael Cabral
§
Mineral Deposits, Technische Universität Clausthal, Adolph-Roemer-Str. 2A, 38678 Clausthal-Zellerfeld, Germany
§Corresponding author e-mail address: alexandre.cabral@tu-clausthal.de
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Atlas Vasconcelos CorrÊA Neto
Atlas Vasconcelos CorrÊA Neto
Universidade Federal do Rio de Janeiro, Instituto de Geociências, Departamento de Geologia, Rio de Janeiro, RJ, Brazil
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The Canadian Mineralogist (2015) 53 (6): 1061–1072.
Article history
received:
05 Jun 2015
accepted:
13 Oct 2015
first online:
17 Nov 2017
Citation
Alexandre Raphael Cabral, Atlas Vasconcelos CorrÊA Neto; Empirical Bi8Te3 and Bi2Te from the SÃo SebastiÃo Gold Deposit, Brazil: Implications For Lode-gold Mineralization in Minas Gerais. The Canadian Mineralogist ; 53 (6): 1061–1072. doi: https://doi.org/10.3749/canmin.1500066
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Index Terms/Descriptors
- alloys
- bismuth
- Brazil
- chalcopyrite
- electron microscopy data
- gold
- gold ores
- greenstone
- hedleyite
- host rocks
- hydrothermal conditions
- joseite
- metal ores
- metals
- metamorphic rocks
- Minas Gerais Brazil
- mineralization
- ring silicates
- schists
- SEM data
- silicates
- South America
- sulfides
- tellurides
- tourmaline group
- Passagem de Mariana Mine
- Pitangui greenstone belt
- Sao Sebastiao Deposit
Latitude & Longitude