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GEOREF RECORD

Alabandite (MnS) in metamorphosed manganiferous rocks at Morro da Mina, Brazil; palaeoenvironmental significance

Alexandre Raphael Cabral, Armin Zeh, Nivea Cristina da Silva Viana, Marco Paulo de Castro, Frantisek Laufek, Bernd Lehmann and Glaucia Queiroga
Alabandite (MnS) in metamorphosed manganiferous rocks at Morro da Mina, Brazil; palaeoenvironmental significance
European Journal of Mineralogy (July 2019) Pre-Issue Publication

Abstract

The mineral alabandite, cubic MnS with variable amounts of FeS, occurs in a number of mineral assemblages in manganiferous metasedimentary rocks, some of which are mined as manganese ore. One of them is Morro da Mina, Mina Gerais, Brazil, where alabandite is a minor component of "queluzite," a manganese-silicate-carbonate rock. The Morro da Mina alabandite contains 7.3 + or - 1.4 mol% FeS and makes up aggregates with graphite and molybdenite. A comparison of alabandite occurrences worldwide indicates four main types of mineral assemblages: (1) alabandite + graphite; (2) alabandite + graphite + molybdenite; (3) alabandite + rhodochrosite + molybdenite; (4) and alabandite + rhodochrosite. The different assemblages suggest that manganese sulfide formed in a range of marine palaeoenvironments, from highly reducing and sulfidic -- i.e., euxinic -- settings to manganese-oxide-precipitating conditions. Morro da Mina represents assemblage (2), which is characteristic of a euxinic water column in a stratified ocean. In general, our comparison of alabandite-bearing mineral assemblages indicates that palaeoenvironmental information can be retrieved from sedimentary rocks that experienced variable degrees of metamorphic overprint.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: Pre-Issue Publication
Title: Alabandite (MnS) in metamorphosed manganiferous rocks at Morro da Mina, Brazil; palaeoenvironmental significance
Affiliation: Universidade Federal de Minas Gerais, Instituto de Geociencias, Belo Horizonte, Brazil
Published: 20190729
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 56
Accession Number: 2019-067072
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch map
S20°36'00" - S20°36'00", W43°46'59" - W43°46'59"
Secondary Affiliation: Karlsruher Institut fuer Technologie, DEU, GermanyVale Manganes, BRA, BrazilUniversidade Federal de Ouro Preto, BRA, BrazilCzech Geological Survey, CZE, Czech RepublicTechnische Universitaet Clausthal, DEU, Germany
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201935
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