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Chovanite, Pb (sub 15-2x) Sb (sub 14+2x) S (sub 36) O (sub x) (x approximately 0.2), a new sulphosalt species from the Low Tatra Mountains, Western Carpathians, Slovakia

Dan Topa, Jiri Sejkora, Emil Makovicky, Jaroslav Prsek, Daniel Ozdin, Hubert Putz, Herbert Dittrich and Sven Karup-Moller
Chovanite, Pb (sub 15-2x) Sb (sub 14+2x) S (sub 36) O (sub x) (x approximately 0.2), a new sulphosalt species from the Low Tatra Mountains, Western Carpathians, Slovakia
European Journal of Mineralogy (August 2012) 24 (4): 727-740

Abstract

Chovanite, a new representative of the group of oxysulphosalts of Pb and Sb was found in three hydrothermal deposits of antimony ore, Dubrava, Male Zelezne, and Klacianka, situated on the northern slopes of the Low Tatra Mountains, Slovakia. It is associated with other Pb-Sb sulphosalts, especially boulangerite, robinsonite and dadsonite. In reflected light, chovanite is white, bireflectance is distinct already in air. Pleochroism is present; colour varies from white with a yellowish green tint (darkest position) to white with a faint bluish tint (lightest position). Reflectance values in air are R (sub max) -R (sub min) (%) (lambda nm): 43.6-37.7 (470), 43.0-36.7 (546), 41.3-35.4 (589), 39.2-34.0 (650). Anisotropy is moderate to strong both in air and in oil, with blue grey to brown grey polarization colours. Internal reflections and twinning are absent. The optical properties are very similar to boulangerite. Micro-indentation hardness is 222.5 with a range 213-238. Derived Mohs hardness is 3. Cleavage is good, parallel to the c axis. Simplified chemical formula based on electron-microprobe analyses is Pb (sub 14.42(35)) Sb (sub 14.33(11)) S (sub 36.04(23)) , Z=4, which corresponds to Pb 50.74, Sb 29.63, S 19.62, total 100.00 wt%. No other elements exceed detection limits; chlorine is absent and oxygen was not measured. Structural formula is Pb (sub 15-2) (sub x) Sb (sub 14+2) (sub x) S (sub 36) O (sub x) (Z=4) for which the above mean of microprobe measurement data and the structure refinement give the value of x equal to approximately 0.2. Density (calc.) is 7.14 g/cm (super 3) . Crystal system is monoclinic, space group C2/m, lattice parameters a=48.189(48) Aa, b=4.1104(40) Aa, c=34.235(35) Aa, beta =106.059(15) degrees , V=6517(11) Aa (super 3) , Z=4. Chovanite belongs to a sulphosalt family of boxwork structures, together with pellouxite, scainiite, pillaite, marruccite, vurroite, neyite, and several synthetic sulphosalts. Its crystal structure contains 11 independent lead sites, 13 coordination polyhedra of antimony, some of them with Sb sites split into two partially occupied non-overlapping positions, and five mixed Pb, Sb sites. The boxwork structure of chovanite is formed by a combination of three types of structural modules: (a) continuous walls with a complex structure of rod-layer type; these walls are interconnected by (b) rod-like partitions, and the resulting box-like channels (c) are filled by still another type of structure rods. Chovanite has the largest box-like channel system and infill elements known at present. In spite of differences in chemical composition, chovanite is structurally closest to pellouxite (Cu,Ag) (sub 2) Pb (sub 21) Sb (sub 23) S (sub 55) ClO which has a moderately large boxwork channel system.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 24
Serial Issue: 4
Title: Chovanite, Pb (sub 15-2x) Sb (sub 14+2x) S (sub 36) O (sub x) (x approximately 0.2), a new sulphosalt species from the Low Tatra Mountains, Western Carpathians, Slovakia
Affiliation: Paris-Lodron University of Salzburg, Department of Materials Engineering and Physics, Salzburg, Austria
Pages: 727-740
Published: 201208
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 36
Accession Number: 2012-073270
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 8 tables, geol. sketch map
N48°59'13" - N48°59'13", E19°30'18" - E19°30'18"
Secondary Affiliation: National Museum, CZE, Czech RepublicUniversity of Copenhagen, DNK, DenmarkUniversity of Science and Technology, POL, PolandComenius University, SVK, SlovakiaTechnical University of Denmark, DNK, Denmark
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201238
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