Erythrite

Formula: Co3(AsO4)2 · 8H2O

Colour: Crimson to peach red, pale rose, pink

Lustre: Sub-Vitreous, Waxy, Pearly, Dull, Earthy

Hardness: 1½ – 2½

Specific Gravity: 3.06

Crystal System: Monoclinic. Erythrite occurs as deeply striated, prismatic to acicular crystals, commonly rediating, globular tufts or crystals, or as a coating

Member of: Vivianite group, Annabergite-Erythrite Series

Name: Named in 1832 by François Sulpice Beaudant from the Greek έρυθρος, “erythros” for “red”.

Type Locality: Daniel Mine (St. Daniel Mine), Neustädtel, Schneeberg, Erzgebirgskreis, Saxony, GermanyCommonly called cobalt bloom, erythrite is a cobalt arsenate hydrate, that forms in the oxidized zones of cobalt and nickel deposits. Due to its bright color, it is used to indicate the presence of cobalt-nickel-silver ore.

The cobalt analogue of annabergite and köttigite.