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GEOREF RECORD

Laforetite, AgInS (sub 2) , a new mineral of the chalcopyrite group from the Montogros Mine, Haute-Loire, France

Nicolas Meisser, Philippe Thelin, Pierre-Jacques Chiappero and Colette Maurel
Laforetite, AgInS (sub 2) , a new mineral of the chalcopyrite group from the Montogros Mine, Haute-Loire, France
European Journal of Mineralogy (October 1999) 11 (5): 891-897

Abstract

Laforetite, AgInS (sub 2) , is a new mineral from the Montgros Pb-Zn mine, Haute-Loire, France. It occurs as very small, less than 30 mu m, anhedral inclusions in galena, which is associated with sphalerite, barite, carbonates and quartz. The new species is brownish grey with abundant red internal reflections in plane polarized light; under crossed nicols in oil immersion, it presents a strong anisotropy with red brick orange to bluish-grey purplish tints and polysynthetic twins. Electron-microprobe analysis yields (mean of 8 analyses): Ag 37.68, Cu 0.04, In 40.22, Fe 0.02, S 22.42, Se 0.01, total 100.39 wt.%. The simplified formula is AgInS (sub 2) . Because of the material paucity, X-ray powder patterns were obtained from a very small inclusion (20X30 mu m) with a microdiffractometer using the reflection geometry. Parameters refined from a tetragonal cell (by comparison with the synthetic low-temperature from of AgInS (sub 2) ) are: a = 5.880 (2), c = 11.21 (1) Aa, V = 387.57 (1) Aa (super 3) ; space group I 42d (no. 122) and Z = 4. Laforetite is the silver analogue of roquesite and belongs to the chalcopyrite group. The name honours Claude Laforet (BRGM, Orleans), a metallographer who first identified this mineral in the Montgros mine.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 11
Serial Issue: 5
Title: Laforetite, AgInS (sub 2) , a new mineral of the chalcopyrite group from the Montogros Mine, Haute-Loire, France
Affiliation: Musee Geologique & Institut de Mineralogie et de Geochimie, Lausanne, Switzerland
Pages: 891-897
Published: 199910
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 19
Accession Number: 1999-070068
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
N44°55'00" - N45°15'00", E03°00'00" - E04°30'00"
Secondary Affiliation: Museum National d'Histoire Naturelle, FRA, FranceCRSCM-CNRS, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199924
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