Andyrobertsite
Andyrobertsite | |
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A mixture of andyrobertsite (blue) and calcioandyrobertsite (green), holotype specimen; size: 3.3×2.2×1.0 mm | |
General | |
Category | Arsenate mineral |
Formula (repeating unit) | KCdCu5(AsO4)4(H2AsO4)·2H2O |
Strunz classification | 08.DH.50 08 |
Dana classification | 42.09.02.03 |
Crystal system | Monoclinic – Prismatic; H-M symbol (2/m), space group P21/m |
Unit cell | a = 9.81, b = 10.034, c = 9.975, Z = 2 |
Identification | |
Color | Blue |
Crystal habit | Platy |
Cleavage | {100} good |
Mohs scale hardness | 3 |
Luster | Vitreous |
Streak | Pale blue |
Diaphaneity | Transparent |
Specific gravity | 4 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.72, nβ = 1.749, nγ = 1.757 |
Birefringence | δ = 0.037 |
References | [1][2] |
Andyrobertsite is a rare, complex arsenate mineral with a blue color. It is found in the Tsumeb mine in Namibia and named after Andrew C. Roberts (b. 1950), mineralogist with the Geological Survey of Canada. A Ca-rich analogue (with Ca instead of Cd) is called calcioandyrobertsite and has a more greenish tint.[2]
References
- ↑ Andyrobertsite. Mindat.org
- 1 2 Andyrobertsite. Webmineral.com
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