Manganese valency and the colour of the Mn₂AsO₄(OH) polymorphs eveite and sarkinite

Authors: Hålenius U.¹; Westlund E.²

Source: Mineralogical Magazine, Volume 62, Number 1, 1 February 1998 , pp. 113-119(7)

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Abstract:

Polarized optical absorption spectra of single crystals of the two dimorphic Mn₂AsO₄(OH)-minerals eveite and sarkinite show that minor concentrations of Mn³⁺ at the octahedral site determine the colour and cause the distinct pleochroism in green and yellow of eveite. In the sarkinite spectra only absorption bands due to spin-forbidden d-d transitions in Mn²⁺ at six- and five-coordinated sites are observed, which produce a weak flesh-red mineral colour and a very faint pleochroism.

Keywords: EVEITE; SARKINITE; OPTICAL; SPECTROSCOPY; LANGBAN; SWEDEN

Language: English

Document Type: Research article

Affiliations: 1: Department of Mineralogy, Swedish Museum of Natural History, P.O. Box 50007, SE-10405 Stockholm, Sweden 2: Department of Geology and Geochemistry, Stockholm University, SE-10691 Stockholm, Sweden

Publication date: 1998-02-01

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