Andyrobertsite
Appearance
Andyrobertsite | |
---|---|
![]() 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 |
IMA symbol | Arb[1] |
Strunz classification | 8.DH.50 08 |
Dana classification | 42.09.02.03 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/m |
Unit cell | a = 9.81, b = 10.034 c = 9.975 [Å]; β = 101.83°; 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 | [2][3] |
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.[3]
References
[edit]- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Andyrobertsite. Mindat.org
- ^ a b Andyrobertsite. Webmineral.com