andyrobertsite

{{Infobox mineral | name = Andyrobertsite | category = Arsenate mineral | boxwidth = | boxbgcolor = | image = Andyrobertsite-Calcioandyrobertsite-117541.jpg | imagesize = 260px | alt = | caption = A mixture of andyrobertsite (blue) and calcioandyrobertsite (green), holotype specimen; size: 3.3×2.2×1.0 mm | formula = KCdCu5(AsO4)4(H2AsO4)·2H2O |IMAsymbol=Arb | molweight = | strunz = 8.DH.50 08 | dana = 42.09.02.03 | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = P21/m | unit cell = a = 9.81, b = 10.034 c = 9.975 [Å]; β = 101.83°; Z = 2 | color = Blue | habit = Platy | twinning = | cleavage = {100} good | tenacity = | mohs = 3 | luster = Vitreous | refractive = nα = 1.72, nβ = 1.749, nγ = 1.757 | opticalprop = Biaxial (-) | 2V = | birefringence = δ = 0.037 | pleochroism = | streak = Pale blue | gravity = 4 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent | other = | references = }}

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.