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Chemical composition and vibrational spectral of tungsten-bearing goethite and hematite from western Rhodopes, Bulgaria

Mihail Tarassov, Boriana Mihailova, Eugenia Tarassova and Ludmil Konstantinov
Chemical composition and vibrational spectral of tungsten-bearing goethite and hematite from western Rhodopes, Bulgaria
European Journal of Mineralogy (October 2002) 14 (5): 977-986

Abstract

The incorporation of W into goethite and hematite in the supergene environment of the Grantcharitza tungsten deposit in the Western Rhodopes is discussed via results from SEM, EPMA, XRD and micro-Raman spectroscopy. The sample is a collofirm black material consisting mainly of goethite with WO (sub 3) 6.83-10.85 wt.% and of several products of its alteration, including a W-poor goethite with WO (sub 3) 1.35-5.72 wt.%, a W-rich ferric iron oxide phase with WO (sub 3) 22.19-25.12 wt.% and hematite with WO (sub 3) 1.21-1.72 wt.%. The presence of W atoms in the structures of hematite and goethite causes the appearance of a low-frequency shoulder in the Raman peak near 400 cm (super -1) . In both minerals, only a small amount of W occupies Fe positions, while the major part of the W forms W-O self-assembled clusters generating a broad band between 580 and 750 cm (super -1) in the Raman spectra. Tungsten is organized in chain-like clusters of corner-sharing WO (sub 6) octahedra with an average W-O-W bond angle of approximately 150 degrees .


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 14
Serial Issue: 5
Title: Chemical composition and vibrational spectral of tungsten-bearing goethite and hematite from western Rhodopes, Bulgaria
Affiliation: Bulgarian Academy of Sciences, Central Laboratory of Mineralogy and Crystallography, Sofia, Bulgaria
Pages: 977-986
Published: 200210
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 32
Accession Number: 2002-071659
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
N41°12'00" - N42°17'60", E23°04'60" - E26°15'00"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200222
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