Erythrite, also known as red cobalt, previously cobalt ochre: 172 is a secondary hydrated cobalt arsenate mineral with the formula Co3(AsO4)2•8H2O. Erythrite and annabergite, chemical formula Ni3(AsO4)2•8H2O, or nickel arsenate form a complete series with the general formula (Co,Ni)3(AsO4)2•8H2O.
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, and takes its name from the Greek έρυθρος (erythros), meaning red. 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.
Erythrite occurs as a secondary mineral in the oxide zone of Co–Ni–As bearing mineral deposits. It occurs in association with cobaltite, skutterudite, symplesite, roselite-beta, scorodite, pharmacosiderite, adamite, morenosite, retgersite, and malachite.
Notable localities are Cobalt, Ontario; La Cobaltera, Chile, Schneeberg, Saxony, Germany; Joachimsthal, Czech Republic; Cornwall, England; Bou Azzer, Morocco; the Blackbird mine, Lemhi County, Idaho; Sara Alicia mine, near Alamos, Sonora, Mexico; Mt. Cobalt, Queensland and the Dome Rock copper mine, Mingary, South Australia.
Other varieties
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).
Further reading
- Dana's Manual of Mineralogy ISBN 0-471-03288-3
- Manual of Mineral Science, 22nd Ed. C. Klein.ISBN 0-471-25177-1
- Faye, G H; Nickel, E H (1968). "The origin of pleochroism in erythrite" (PDF). The Canadian Mineralogist. 9: 492–504.
References
Krivovichev V. G. Mineralogical glossary. Scientific editor A. G. Bulakh. — St.Petersburg: St.Petersburg Univ. Publ. House. 2009. — 556 p. — ISBN 978-5-288-04863-0 https://uk.wikipedia.org/wiki/%D0%91%D1%83%D0%BB%D0%B0%D1%85_%D0%90%D0%BD%D0%B4%D1%80%D1%96%D0%B9_%D0%93%D0%BB%D1%96%D0%B1%D0%BE%D0%B2%D0%B8%D1%87 ↩
Barthelmy, David (2014). "Erythrite Mineral Data". Webmineral.com. Retrieved 27 July 2022. http://www.webmineral.com/data/Erythrite.shtml ↩
"Erythrite". Mindat.org. Retrieved 27 July 2022. http://www.mindat.org/show.php?id=1407 ↩
Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Erythrite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 27 July 2022. http://www.handbookofmineralogy.org/pdfs/erythrite.pdf ↩
Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Erythrite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 27 July 2022. http://www.handbookofmineralogy.org/pdfs/erythrite.pdf ↩