What is Roselite?
Roselite is a rose-pink hydrated cobalt arsenate, a vivid secondary phosphate valued for colour and its place in oxidised cobalt-arsenic deposits.
Mineralogy and crystal structure
Reference formula: Ca2Co(AsO4)2·2H2O. Roselite is monoclinic and forms a series with related calcium-magnesium-cobalt arsenates. The selected COD model is an exact roselite entry; chemistry may vary through substitution. Roselite is classified with phosphates and has a monoclinic crystal system. Typical hardness is 3.5–4 on the Mohs scale and specific gravity is approximately 3.5–3.7.
Colour, lustre and habit
Typical colours include rose-red, pink, violet, purple. The usual prismatic, granular, crusty habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Roselite forms in or is associated with oxidised cobalt-arsenic veins and phosphate-rich secondary zones. Important documented localities include Bou Azzer in Morocco, Schneeberg in Germany, Chile, Mexico and other cobalt districts.
Rose colour from a cobalt-arsenic vein
Roselite is a high-impact small specimen: strong colour, a secondary-mineral story and an unusual cobalt-arsenate composition make even modest crystals attractive to specialists.
Collecting and care
Keep enclosed and away from dust, acids and food-contact areas. Do not cut or grind arsenic-bearing specimens and wash hands after handling.
