Wiserite, an Occurrence at the Kombat Mine in Namibia, and New Data

Pete J. Dunn; Carl A. Francis; Robert A. Ramik; Joseph A. Nelen; John Innes

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Other| December 01, 1989

Wiserite, an Occurrence at the Kombat Mine in Namibia, and New Data

Pete J. Dunn;

Pete J. Dunn

Department of mineral sciences, smithsonian institution, washigton, D.C. 20560, U.S.A.

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Carl A. Francis;

Carl A. Francis

Harvard mineralogical museum, 24 oxford street, Cambridge, Massachusetts 02138, U.S.A.

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Robert A. Ramik;

Robert A. Ramik

Department of minerology, Royal Ontario Museum, Toronto, Ontario M5S 2C6, Canada.

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Joseph A. Nelen;

Joseph A. Nelen

Department of Mineral Sciences, Smithsonian Institution, Washigton, D.C.20560, U.S.A.

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John Innes

182 Bielby Road, Kenmore Hills, Brisbane, Queensland, Australia

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Author and Article Information

Pete J. Dunn

Department of mineral sciences, smithsonian institution, washigton, D.C. 20560, U.S.A.

Carl A. Francis

Harvard mineralogical museum, 24 oxford street, Cambridge, Massachusetts 02138, U.S.A.

Robert A. Ramik

Department of minerology, Royal Ontario Museum, Toronto, Ontario M5S 2C6, Canada.

Joseph A. Nelen

Department of Mineral Sciences, Smithsonian Institution, Washigton, D.C.20560, U.S.A.

John Innes

182 Bielby Road, Kenmore Hills, Brisbane, Queensland, Australia

Publisher: Mineralogical Society of America

First Online: 02 Mar 2017

Online ISSN: 1945-3027

Print ISSN: 0003-004X

American Mineralogist (1989) 74 (11-12): 1374–1376.

Abstract

Wiserite, a very rare manganese borate, has been found at the Kombat mine, Namibia, associated with hausmannite, alleghanyite, and pyrobelonite on the hanging-wall side of a 2-m-thick lens of manganeseo xide ore. Its formula, derived in part from a crystal-structure analysis by Pertlik and Dunn (1989), is {Mn₁₄(B₂O₅)₄(OH)₈}{[Si_1-xMg_x][O_1-x(OH_x]₄Cl_2x}Wiserite occurs as pinkish brown prismatic crystals up to 1 cm in length. Optically it is uniaxial, negative, with ω = 1.751 and ε = 1.700( both ±0.003). Its density is 3.54 g/cm³(meas.) and 3.57 g/cm³( calc.).Wiserite is tetragonal, P4/n with a = 20.192(6) and C = 3.281(2) Å, Z=2.