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Vochtenite, (Fe2+,Mg)Fe3+[UO2/PO4]4(OH). 12–13 H2O, a new uranyl phosphate mineral from Wheal Basset, Redruth, Cornwall, England

Published online by Cambridge University Press:  05 July 2018

P. C. Zwaan ,
C. E. S. Arps  and
E. de Grave
P. C. Zwaan
Affiliation:
Rijksmuseum van Geologie en Mineralogie, Hooglandse Kerkgracht 17, 2312 HS Leiden, The Netherlands
C. E. S. Arps
Affiliation:
Rijksmuseum van Geologie en Mineralogie, Hooglandse Kerkgracht 17, 2312 HS Leiden, The Netherlands
E. de Grave
Affiliation:
Laboratorium voor Magnetisme, Rijksuniversiteit Gent, Proeftuinstraat 42, 9000 Gent, Belgium
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Abstract

Vochtenite, a new mineral from the Basset Mine, southeast of Camborne in Cornwall, England, is a ferrous-ferric magnesium-bearing hydroxy uranyl phosphate mineral. It is monoclinic with a = 12.606, b = 19.990, c = 9.990 Å, β = 102.31° Z = 3; the ideal formula is:

The strongest lines in the X-ray powder diffraction pattern are: 9.998(100)(020), 4.999(30)(040), 4.892(45)(002), 3.475(70)(311), 3.333(50)(060), 3.087(40)(232), and . Vochtenite is brown in colour with a bronzy lustre and is non-fluorescent. Mohs hardness is 2.5 and the density (calc.) = 3.663 g/cm3. There is a prominent (010) cleavage. Vochtenite is optical biaxial negative, 2V (calc.) = 89(3)° its dispersion is indiscernible. Refractive indices are α = 1.575(2), β = 1.589(2), γ = 1.603(2), and the pleochroism is very weak. Orientation X(α)∥b is perpendicular to (010) and Z(γ)∧c is small. The mineral occurs as subparallel (0.5–1.0 mm) crystal aggregates with a pseudo-quadratic outline. The mineral is named vochtenite after Prof. Dr. Ing. R. F. C. Vochten of the State University of Antwerpen, Belgium.

Keywords

vochtenitenew mineraluranyl phosphate groupWheal BassetCornwallEngland
Type
Mineralogy
Information
Mineralogical Magazine , Volume 53 , Issue 372 , September 1989 , pp. 473 - 478
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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