What is Quenstedtite?
Quenstedtite is a delicate lilac to violet hydrated iron sulfate, a classic secondary mineral of acidic oxidation zones and mine environments.
Mineralogy and crystal structure
Reference formula: Fe2(SO4)3·11H2O. The selected triclinic COD model represents the hydrated sulfate structure. Quenstedtite is soft and water-sensitive; colour and hydration can change, so fresh material and careful storage are important. Quenstedtite is classified with sulfates and has a triclinic crystal system. Typical hardness is 2–2.5 on the Mohs scale and specific gravity is approximately 2.0–2.2.
Colour, lustre and habit
Typical colours include lilac, violet, pink, white. The usual crusty, fibrous, tabular habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Quenstedtite forms in or is associated with acid sulfate oxidation zones, mine dumps and weathering environments where iron sulfides generate acidic, sulfate-rich fluids. Important documented localities include historic European mine districts, including German localities, and other authenticated acid-sulfate occurrences.
Lilac colour from an acidic mine environment
Quenstedtite is a beautiful reminder that mine weathering can create fragile secondary minerals. Its violet colour attracts collectors, while its sensitivity makes preservation and provenance part of the specimen's value.
Collecting and care
Keep completely dry, avoid water, humidity, heat and direct handling, and store in a sealed stable container with its locality label.
