What is Scorodite?
Scorodite is a blue-green hydrated iron arsenate, valued for transparent crystals and vivid colour in oxidised arsenic-rich ore deposits.
Mineralogy and crystal structure
Reference formula: FeAsO4·2H2O. Scorodite is orthorhombic and commonly forms delicate prismatic crystals. Its colour can change with dehydration, and its arsenic content makes it a mineral for careful display. Scorodite is classified with phosphates and has a orthorhombic crystal system. Typical hardness is 3.5–4 on the Mohs scale and specific gravity is approximately 3.1–3.3.
Colour, lustre and habit
Typical colours include blue, blue-green, green, violet, brown. The usual prismatic, pyramidal, crusty habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Scorodite forms in or is associated with oxidised zones of arsenic-bearing hydrothermal veins and mine dumps. Important documented localities include Germany, Portugal, Mexico, Namibia, Australia and the United States.
Blue-green colour from arsenic oxidation
Scorodite is a collector mineral where colour and chemistry point to the same process: oxidation of an arsenic-bearing ore system. Fresh transparent crystals are especially desirable.
Collecting and care
Keep sealed, dry and away from dust, children and food. Do not cut, grind or heat; handle with gloves when preparing fragile specimens.
