March 2026 – Erythrite

Just in time for the arrival of spring, flowers are also blooming in the Mineralogical State Collection. That’s because our mineral of the month is also known as cobalt flower or, to use its mineralogically correct name, erythrite. (Chemical formula: Co3[AsO4]2 · 8H2O)

Erythrite is a secondary cobalt mineral that is formed by oxidation from other cobalt minerals such as skutterudite and cobaltite. Like many secondary minerals of transition metals, erythrite is characterised by its strong colour. For this reason, the mineral was formerly processed into the pigment cobalt violet, which is highly toxic and has since been replaced by alternative dyes.

Chemical formula: Co3[AsO4]2 · 8H2O

Location: Bou-Azzer, Ouarzazate Province, Morocco