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The X-Ray Crystallography of Rosasite From Tsumeb, Namibia

Published online by Cambridge University Press:  10 January 2013

Andrew C. Roberts
Affiliation:
Geological Survey of Canada, 601 Booth Street, Ontario, Ontario, Canada K1A 0E8
John L. Jambor
Affiliation:
CANMET, 555 Booth Street, Ottawa, Ontario, Canada K1A 0G1
Joel D. Grice
Affiliation:
Mineral Sciences Division, National Museum of Natural Sciences, 1926 Merivale Road, Ottawa, Ontario, Canada K1A 0M8

Abstract

Crystals of green to bluish green rosasite from Tsumeb, Namibia are monoclinic, space group P21/a, with refined unit-cell parameters a = 12.873 (3), b = 9.354 (3), c = 3.156 (2) A, β = 110.36 (3)°, V = 356.3 (5) A3 and a:b:c = 1.3762:1:0.3374, with Z = 4 and Dx = 4.15 g./cm.3. Crystals are twinned by 180° rotation about a*. A fully indexed powder pattern is presented. Electron-microprobe analyses, average (wt. %): Cu 32.9, Zn 23.7; this suggests an analytical formula of (Cu1·18 Zn0·82) (CO3) (OH)2. The rosasite is optically biaxial negative, α = 1.673 (1), β = 1.796 (3), γ = 1.811 (3), 2Vx = 33 (5)° (calc. 36.4°), with X = c, Y = a* and Z = b.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1986

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References

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