Scorodite: Gemstones Information

Scorodite is Fe3AsO42H2O and forms tabular, prismatic or pyramidal pale leek green, blue to brown semitransparent crystals of the orthorhombic system. The hardness is 3.5–4 and the SG 3.28–3.29. The RI for the alpha, beta and gamma rays is 1.741–1.784, 1.744–1.805, 1.768–1.820,biaxial positive with birefringence 0.027–0.030. Pleochroism is strong,purple to blue and a strong absorption line can be seen at 450 nm with broad absorption in the green. It is soluble in HCl. Scorodite is a secondary mineral formed by the oxidation of As-bearing sulphides. Some large pleochroic blue crystals are found at Tsumeb, Namibia and scorodite also occurs at the Ojuela mine, Mapimi, Durango, Mexico.