What is Walstromite?
Walstromite is a barium calcium silicate related to wollastonite, valued for its rare occurrence and delicate pale crystals in skarn assemblages.
Mineralogy and structure
Reference formula: BaCa2Si3O9. Walstromite is triclinic with the ideal formula BaCa2Si3O9. COD 9016694 is an exact structural reference from a published walstromite study. Walstromite is classified with silicates and has triclinic crystal symmetry. Typical hardness is 5–6 on the Mohs scale and specific gravity is approximately 3.1–3.2.
Colour, lustre and habit
Typical colours include colourless, white, cream, pale blue. The usual tabular, granular, massive habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Walstromite forms in or is associated with barium-rich skarns, contact-metamorphic limestones and high-temperature silicate assemblages. Important documented localities include California and other western United States localities, Russia, Italy and Germany.
A rare barium silicate related to wollastonite
Walstromite is a strong specialist addition because it connects a familiar silicate family with a rare barium-rich skarn environment.
Collecting and care
Protect from acids, scratches and impact; clean gently and retain the skarn association and locality.
