What is Valentinite?
Valentinite is an orthorhombic antimony oxide, commonly found as pale sprays or crusts in oxidised antimony deposits and valued for its delicate crystal habit.
Mineralogy and structure
Reference formula: Sb2O3. Valentinite is the orthorhombic dimorph of cubic senarmontite. The exact COD 9000012 structure is used; antimony-bearing material should be treated as a protected ore specimen. Valentinite is classified with oxides and has orthorhombic crystal symmetry. Typical hardness is 2.5–3 on the Mohs scale and specific gravity is approximately 5.5–5.8.
Colour, lustre and habit
Typical colours include white, colourless, grey, yellowish. The usual prismatic, bladed, radiating habit and adamantine, vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Valentinite forms in or is associated with oxidised antimony veins, weathering zones and secondary cavities above stibnite-rich ore. Important documented localities include Romania, Bolivia, Mexico, France, Italy, China and the United States.
Pale oxide sprays above an antimony vein
Valentinite rewards close viewing: delicate pale needles and sprays show the oxidation history of a metallic ore. Freshness, association and locality are more important than size alone.
Collecting and care
Keep enclosed and away from dust, children and food. Do not grind, heat or acid-test; wash hands after handling.
