Perroudite, a new sulfide-halide of Hg and Ag from Cap-Garonne, Var, France, and from Broken Hill, New South Wales, and Coppin Pool, western Australia
Perroudite is a new sulfo-halide of Hg and Ag from Cap-Garonne, Var, France; Broken Hill, New South Wales; and Coppin Pool, Western Australia, Australia. Averaged microprobe analyses gave the following formulae: Hg/sub 5.04/Ag/sub 4.03/S/sub 3.96/(Cl/sub 1.55/I/sub 1.55/Br/sub 0.87/)/sub ..sigma..3.97/ (Cap-Garonne), Hg/sub 5.0/Ag/sub 4.2/S/sub 5.45/(I/sub 1.6/Cl/sub 1.55/Br/sub 0.25/)/sub ..sigma..3.4/ (Broken Hill), and Hg/sub 5.7/Ag/sub 3.5/S/sub 5.4/(Cl/sub 2.0/I/sub 1..0/Br/sub 0.5/)/sub ..sigma..3.5/ (Coppin Pool). A structure determination of a Coppin Pool crystal gave the general formula Hg/sub 5-x/Ag/sub 4+x/S/sub 5-x/(Cl,I,Br)/sub 4+x/ (-1.4 < x < 1.4). The mineral is orthorhombic, space group P2/sub 1/2/sub 1/2, with a = 17.47(3), b = 12.23(2), c = 4.29(2) A, V = 917.5 A/sup 3/, and Z = 2. The averaged calculated density is 6.92 gcm/sup 3/. Perroudite forms bright red, transparent prismatic crystals to 0.07 mm in length, elongated along (001) and often flattened on /100/. Luster vitreous to adamantine; streak orange-red; brittle with one perfect cleavage on (100); fracture irregular. The refractive indices are in the range 2.3-2.4; the mineral is biaxial positive; 2V/sub meas/ = 70/sup 0/; dispersion r > v (very strong); pleochroism marked from brownish-red to yellow to brownish-yellow. Perroudite forms from the alteration of Hg- and Ag-bearing tennantite at the type locality (Cap-Garonne). At Broken Hill it occurs in massive white kaolinite associated with silver halides, native silver and native gold, and possibly other mercury-bearing minerals. At Coppin Pool, perroudite occurs with supergene minerals such as covellite, cerussite, anglesite, phosgenite, etc., derived by the weathering of galena in a quartz vein. Halide-rich solutions are implicated in the formation of perroudite at all three occurrences.
- Research Organization:
- Natural History Museum, Geneva (Switzerland)
- OSTI ID:
- 6996863
- Journal Information:
- Am. Mineral.; (United States), Vol. 72:11-12
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HALIDE MINERALS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
PETROGRAPHY
STRUCTURAL CHEMICAL ANALYSIS
DENSITY
ELECTRON MICROPROBE ANALYSIS
FRANCE
MERCURY COMPOUNDS
MINERALOGY
NEW SOUTH WALES
SILVER COMPOUNDS
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X-RAY DIFFRACTION
AUSTRALASIA
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CHEMICAL ANALYSIS
COHERENT SCATTERING
DIFFRACTION
EUROPE
MICROANALYSIS
MINERALS
PHYSICAL PROPERTIES
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TRANSITION ELEMENT COMPOUNDS
WESTERN EUROPE
580300* - Mineralogy
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