Andyrobertsite
(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]
(same H-M symbol)
c = 9.975 [Å]; β = 101.83°; Z = 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.[3]
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