erythrite

{{Short description|Hydrated cobalt arsenate mineral}}

{{infobox mineral

| name = Erythrite

| category = Arsenate mineral

| boxwidth =

| boxbgcolor = #b72659

| boxtextcolor = white

| image = Érythrite (Maroc).jpg

| imagesize = 260px

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| caption =

| formula = Co₃(AsO₄)₂·8H₂O

| IMAsymbol = Ery{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| molweight =

| strunz = 8.CE.40

| dana = 40.03.06.03

| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = C2/m

| color = Crimson to peach-red, pale rose, or pink, may be zoned

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| habit = Radial or stellate aggregates, fibrous, drusy; usually powdery and massive – rarely as striated prismatic crystals

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| cleavage = Perfect on {{mset|010}}; poor on {{mset|100}} and {{mset|{{overline|1}}02}}.

| fracture =

| tenacity = Sectile

| mohs = 1.5–2.5

| luster = Subadamantine, pearly on cleavages

| streak = Pale red to pink

| diaphaneity = Transparent to translucent

| gravity = 3.06

| density =

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| opticalprop = Biaxial (+)

| refractive = n_α = 1.626 – 1.629 n_β = 1.662 – 1.663 n_γ = 1.699 – 1.701

| birefringence = δ = 0.073

| pleochroism = Visible: X = pale pinkish to pale rose; Y = pale violet to pale violet-rose; Z = deep red

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| references = {{cite web |last1=Anthony |first1=John W. |last2=Bideaux |first2=Richard A. |last3=Bladh |first3=Kenneth W. |last4=Nichols |first4=Monte C. |title=Erythrite |url=http://www.handbookofmineralogy.org/pdfs/erythrite.pdf |website=Handbook of Mineralogy |publisher=Mineral Data Publishing |access-date=27 July 2022 |date=2005}}{{mindat|id=1407|access-date=27 July 2022|title=Erythrite}}{{Cite web|last1=Barthelmy|first1=David|year=2014|url=http://www.webmineral.com/data/Erythrite.shtml|access-date=27 July 2022|title = Erythrite Mineral Data|website=Webmineral.com}}

}}

{{Other uses|Cobalt ochre}}

File:Erytryn (kwiat kobaltu) - Bou Azzer, Atlas, Maroko.jpg

Erythrite, also known as red cobalt, previously cobalt ochreKrivovichev 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{{rp|172}} is a secondary hydrated cobalt arsenate mineral with the formula {{chem|Co|3|(As|O|4|)|2|•8H|2|O}}. Erythrite and annabergite, chemical formula {{chem|Ni|3|(As|O|4|)|2|•8H|2|O}}, or nickel arsenate form a complete series with the general formula {{chem|(Co|,Ni)|3|(As|O|4|)|2|•8H|2|O}}.

Image:Erythrite-176702.jpg

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.{{Citation needed|date=October 2022}}

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.