Erythrite

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title: "Erythrite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["cobalt-minerals", "arsenate-minerals", "monoclinic-minerals", "minerals-in-space-group-12", "vivianite-group", "minerals-described-in-1832"] description: "Hydrated cobalt arsenate mineral" topic_path: "general/cobalt-minerals" source: "https://en.wikipedia.org/wiki/Erythrite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Hydrated cobalt arsenate mineral ::

::data[format=table title="infobox mineral"]

Field	Value
name	Erythrite
category	Arsenate mineral
boxbgcolor	#b72659
boxtextcolor	white
image	Érythrite (Maroc).jpg
imagesize	260px
formula	Co3(AsO4)2·8H2O
IMAsymbol	Ery
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
habit	Radial or stellate aggregates, fibrous, drusy; usually powdery and massive – rarely as striated prismatic crystals
cleavage	Perfect on ; poor on and .
tenacity	Sectile
mohs	1.5–2.5
luster	Subadamantine, pearly on cleavages
streak	Pale red to pink
diaphaneity	Transparent to translucent
gravity	3.06
opticalprop	Biaxial (+)
refractive	nα = 1.626 – 1.629 nβ = 1.662 – 1.663 nγ = 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
references
::

| name = Erythrite | category = Arsenate mineral | boxwidth = | boxbgcolor = #b72659 | boxtextcolor = white | image = Érythrite (Maroc).jpg | imagesize = 260px | alt = | caption = | formula = Co3(AsO4)2·8H2O | IMAsymbol = Ery | 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 | colour = | habit = Radial or stellate aggregates, fibrous, drusy; usually powdery and massive – rarely as striated prismatic crystals | twinning = | cleavage = Perfect on ; poor on and . | 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 = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.626 – 1.629 nβ = 1.662 – 1.663 nγ = 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 | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = | alteration = | references = ::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/8e/Erytryn_(kwiat_kobaltu)_-_Bou_Azzer,_Atlas,_Maroko.jpg" caption="Erythrite (cobalt flower) - Bou Azzer, Atlas Mountains, Morocco."] ::

Erythrite, also known as red cobalt, previously cobalt ochre is a secondary hydrated cobalt arsenate mineral with the formula . Erythrite and annabergite, chemical formula , or nickel arsenate form a complete series with the general formula . ::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/89/Erythrite-176702.jpg" caption="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, 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).

References

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. (2005). "Erythrite". Mineral Data Publishing.
3. "Erythrite".
4. (2014). "Erythrite Mineral Data".
5. ''Krivovichev V. G.'' Mineralogical glossary. Scientific editor [[:uk:Булах Андрій Глібович. A. G. Bulakh]]. — St.Petersburg: St.Petersburg Univ. Publ. House. 2009. — 556 p. — ISBN 978-5-288-04863-0

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