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Gratianite, MnBi (sub 2) S (sub 4) , a new mineral from the Baia Bihor skarn, Romania

Cristiana L. Ciobanu, Joel Brugger, Nigel J. Cook, Stuart J. Mills, Peter Elliott, Gheorghe Damian and Floarea Damian
Gratianite, MnBi (sub 2) S (sub 4) , a new mineral from the Baia Bihor skarn, Romania
American Mineralogist (May 2014) 99 (5-6): 1163-1170

Abstract

The new mineral gratianite, MnBi (sub 2) S (sub 4) , is described from the Baia Bihor skarn deposit, Bihor County, Romania. Gratianite occurs as thin lamellae, intimately intergrown with cosalite and bismuthinite, or as flower-shaped blebs within chalcopyrite, where it is associated with cosalite and tetradymite. Gratianite displays weak to modest bireflectance in air and oil, respectively, and strong anisotropy. The mean empirical composition based on 20 electron probe microanalyses is: (Mn (sub 0.541) Fe (sub 0.319) Pb (sub 0.070) Cu (sub 0.040) Cd (sub 0.009) Ag (sub 0.001) ) (sub S0.980) (Bi (sub 1.975) Sb (sub 0.018) ) (sub S1.993) (S (sub 4.008) Se (sub 0. 012) Te (sub 0.007) ) (sub S4.027) , corresponding to the ideal formula MnBi (sub 2) S (sub 4) . Gratianite crystallizes in the monoclinic system (space group C2/m). Single-crystal X-ray studies of material extracted by the focused ion beam-scanning electron microscopy (FIB-SEM) technique, and carried out on the MX2 macromolecular beamline of the Australian Synchrotron determined the following cell dimensions: a = 12.6774(25) Aa, b = 3.9140(8) Aa, c = 14.7581(30) Aa, b = 115.31(3) degrees , V = 662.0(2) Aa (super 3) , and Z = 4. The six strongest X-ray reflections and their relative intensities are: 3.448 Aa (100), 2.731 Aa (77), 2.855 Aa (64), 3.637 Aa (55), 3.644 Aa (54), and 3.062 Aa (51). Gratianite is the monoclinic analog of berthierite (FeSb (sub 2) S (sub 4) ), garavellite [Fe(Bi,Sb) (sub 2) S (sub 4) ] and clerite [Mn(Sb,As) (sub 2) S (sub 4) ] (Nickel-Strunz class 02.HA.20). It is isostructural with synthetic sulfides and selenides in the MnBi (sub 2) S (sub 4) -MnSb (sub 2) S (sub 4) and MnBi (sub 2) Se (sub 4) -MnSb (sub 2) Se (sub 4) series, and with grumiplucite (HgBi (sub 2) S (sub 4) ) and kudriavite, [(Cd,Pb)Bi (sub 2) S (sub 4) ], (super 3) P members of the pavonite homologous series. The mineral is named for Gratian Cioflica (1927-2002), formerly Professor in Mineralogy and Ore Deposits at the University of Bucharest, Romania. The Baia Bihor skarn, like others within the same belt, is geochemically complex. The availability of Cu, Zn, and Pb, but also Ag, Bi, Mo, and B, as well as a wide range of minor elements, has created an environment allowing for crystallization of an unusually diverse range of discrete minerals. Gratianite is part of the peculiar associations of Bi-Pb-sulfosalts and Bi-chalcogenides that are genetically related to Au-enrichment. This study demonstrates the versatility of FIB-SEM techniques for in situ extraction of small volumes of well-characterized material, coupled with single-crystal X-ray analysis using synchrotron radiation, for the characterization of new minerals.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 99
Serial Issue: 5-6
Title: Gratianite, MnBi (sub 2) S (sub 4) , a new mineral from the Baia Bihor skarn, Romania
Affiliation: University of Adelaide, School of Earth and Environmental Sciences, Adelaide, South Aust., Australia
Pages: 1163-1170
Published: 201405
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 58
Accession Number: 2014-048837
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
N43°40'00" - N48°10'00", E20°15'00" - E29°45'00"
Secondary Affiliation: South Australian Museum, AUS, AustraliaMuseum Victoria, AUS, AustraliaTechnical University of Cluj Napoca, ROM, Romania
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201427
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