Saddlebackite, Pb2Bi2Te2S3, a new mineral species from the Boddington gold deposit, Western Australia

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Authors:Clarke, Richard M.
Author Affiliations:Primary:
Chemistry Centre, Department of Minerals and Energy, East Perth, West. Aust., Australia
Volume Title:Australian Journal of Mineralogy
Source:Australian Journal of Mineralogy, 3(2), p.119-124. Publisher: Mineralogical Societies of New South Wales, Queensland, South Australia, Tasmania and Victoria, Melbourne, Victoria, Australia. ISSN: 1323-7640
Publication Date:1997
Note:In English. 8 refs.; illus., incl. 3 tables
Summary:Saddlebackite was found in a gold-quartz specimen from beneath the lateritic gold orebody at Boddington, ∼ 100 km SE of Perth. It occurs intimately intergrown with gold, aleksite, tsumoite, altaite, galena and other incompletely characterized phases: grey with metallic lustre, sectile, with a platy habit and perfect basal cleavage, but lacking idiomorphic crystal form; VHN20 42, Dcalc 7.61 g/cm3. In reflected light it is opaque, greyish white, very weakly bireflectant and faintly anisotropic; reflectivity in air at 546 nm is 41.8%. EPMA on eight grains gave Pb 35.10, Bi 34.40, Te 23.12, S 7.94, = 100.56, leading to the empirical formula Pb2.00Bi1.94Te2.14S2.92. Indexed XRD powder data are tabulated; strongest lines 3.06(100), 2.115(50), 3.35(40), 2.22(25), 1.311(25), 1.213(25) Å; hexagonal with a 4.230, c 33.43 Å, V 518.0 Å3; Z = 2. Saddlebackite is related chemically and structurally to aleksite, PbSi2Te2S2, both their structures being interpreted as alternating layers, stacked c, of tetradymite and galena composition, in the ratios2:4 and 6:6, respectively. The name is in reference to the Mount Saddleback greenstone belt, within which the Boddington Au deposit is situated. [R.A.H.]
Subjects:Description; Geochemistry; Gold ores; Greenstone belts; Metal ores; Metamorphic belts; New minerals; Optical properties; Physical properties; Sulfides; X-ray diffraction data; Australasia; Australia; Western Australia; Boddington Australia; Saddlebackite
Coordinates:S324400 S324400 E1162200 E1162200
Abstract Numbers:98M/3013
Record ID:2008129319
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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