What is Walthierite?
Walthierite is a rare barium iron-manganese sulfate oxide known from complex oxidised ore assemblages and valued mainly as a specialist reference mineral.
Mineralogy and structure
Reference formula: Ba0.5(Fe,Mn)2(SO4)2O2. Walthierite has variable chemistry and no suitable public COD coordinate entry was selected for this batch. The guide intentionally shows no artificial lattice until a matching structure is verified. Walthierite is classified with sulfates and has orthorhombic crystal symmetry. Typical hardness is 3–4 on the Mohs scale and specific gravity is approximately 4.0–4.5.
Colour, lustre and habit
Typical colours include brown, red-brown, black, yellow-brown. The usual granular, massive, crusty habit and vitreous, resinous, dull lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Walthierite forms in or is associated with complex sulfate-rich oxidation zones, fumarolic or hydrothermal environments and manganese-iron ore assemblages. Important documented localities include Europe and other rare sulfate-oxide localities reported in specialist mineral literature.
A rare sulfate-oxide for the serious collector
Walthierite belongs in a reference collection because its rarity and chemistry are the story. A careful label is more valuable than an unverified decorative structure image.
Collecting and care
Protect from moisture, dust and acids; treat as a specialist sulfate-bearing ore and retain any analytical record.
