Erythrite, also known as red cobalt, is a secondary hydrated cobalt arsenate mineral with the formula Co 3(AsO 4) 2•8H 2O. Erythrite and annabergite, chemical formula Ni 3(AsO 4) 2•8H 2O, or nickel arsenate form a complete series with the general formula (Co,Ni) 3(AsO 4) 2•8H 2O.
Erythrite crystals
Erythrite crystallizes in the monoclinic system and forms prismatic crystals. The color is crimson to pink and occurs as a secondary coating known as cobalt bloom on cobalt arsenide minerals. Well-formed crystals are rare, with most of the mineral manifesting in crusts or small reniform aggregates.
Erythrite was first described in 1832 for an occurrence in Grube Daniel, Schneeberg, Saxony,[4] and takes its name from the Greek έρυθρος (erythros), meaning red.[3] Historically, erythrite itself has not been an economically important mineral, but the prospector may use it as a guide to associated cobalt and native silver.[citation needed]
The nickel variety, annabergite, occurs as a light green nickel bloom on nickel arsenides. In addition iron, magnesium and zinc can also substitute for the cobalt position, creating three other minerals: parasymplesite (Fe), hörnesite (Mg) and köttigite (Zn).
^ abcAnthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Erythrite"(PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 27 July 2022.
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