Atacamite

---

title: "Atacamite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["chloride-minerals", "copper(ii)-minerals", "hydroxide-minerals", "minerals-described-in-1802", "minerals-in-space-group-62", "orthorhombic-minerals"] description: "Halide evaporite mineral" topic_path: "general/chloride-minerals" source: "https://en.wikipedia.org/wiki/Atacamite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Halide evaporite mineral ::

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

Field	Value
name	Atacamite
image	Atacamite on malachite - Mt Gunson mines, South Australia.jpg
imagesize	260px
caption	Atacamite from Mt. Gunson mines, South Australia
category	Halide mineral
formula	Cu2Cl(OH)3
IMAsymbol	Ata
strunz	3.DA.10a
system	Orthorhombic
class	Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
symmetry	Pnma
unit cell	a = 6.03, b = 9.12
c = 6.865 [Å]; Z = 4
color	Bright green, dark emerald-green to blackish green
habit	Slender prismatic crystals, fibrous, granular to compact, massive
twinning	Contact and penetration with complex twinned groupings
cleavage	Perfect on {010}, fair on {101}
fracture	Conchoidal
tenacity	Brittle
mohs	3–3.5
luster	Adamantine to vitreous
streak	Apple green
diaphaneity	Transparent to translucent
gravity	3.745–3.776
opticalprop	Biaxial (−)
refractive	nα = 1.831 nβ = 1.861 nγ = 1.880
birefringence	δ = 0.049
pleochroism	X = pale green; Y = yellow-green; Z = grass-green
2V	Calculated: 74°
dispersion	r
references
::

| name = Atacamite | boxwidth = | boxbgcolor = | image = Atacamite on malachite - Mt Gunson mines, South Australia.jpg | imagesize = 260px | alt = | caption = Atacamite from Mt. Gunson mines, South Australia | category = Halide mineral | formula = Cu2Cl(OH)3 |IMAsymbol=Ata | molweight = | strunz = 3.DA.10a | dana = | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pnma | unit cell = a = 6.03, b = 9.12 c = 6.865 [Å]; Z = 4 | color = Bright green, dark emerald-green to blackish green | colour = | habit = Slender prismatic crystals, fibrous, granular to compact, massive | twinning = Contact and penetration with complex twinned groupings | cleavage = Perfect on {010}, fair on {101} | fracture = Conchoidal | tenacity = Brittle | mohs = 3–3.5 | luster = Adamantine to vitreous | streak = Apple green | diaphaneity = Transparent to translucent | gravity = 3.745–3.776 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.831 nβ = 1.861 nγ = 1.880 | birefringence = δ = 0.049 | pleochroism = X = pale green; Y = yellow-green; Z = grass-green | 2V = Calculated: 74° | dispersion = r | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references =

Atacamite is a copper halide mineral: a copper(II) chloride hydroxide with formula Cu2Cl(OH)3. It was first described from deposits in the Atacama Desert of Chile in 1802 by Dmitri Alekseyevich Golitsyn. The Atacama Desert is also the namesake of the mineral.

Occurrence

Atacamite is polymorphous with botallackite, clinoatacamite, and paratacamite. Atacamite is a comparatively rare mineral, formed from primary copper minerals in the oxidation or weathering zone of arid climates. It has also been reported as a volcanic sublimate from fumarole deposits, as sulfide alteration products in black smokers. The mineral has also been found naturally on oxidized copper deposits in Chile, China, Russia, Czech Republic, Arizona, and Australia. It occurs in association with cuprite, brochantite, linarite, caledonite, malachite, and chrysocolla and its polymorphs.

Synthetic occurrence

Atacamite has been discovered in the patina of the Statue of Liberty, and as alteration of ancient bronze and copper artifacts. The bronze of the Antikythera mechanism had turned to atacamite under the sea.

The mineral has been found as a pigment in sculpture, manuscripts, maps, and frescoes discovered in Eurasia, Russia, and Persia.

Biomineral

Atacamite occurs as a biomineral in the jaws of bloodworms.

Atacamite-235102.jpg|Atacamite prisms from Chile Harvard Museum of Natural History. Atacamite. Miraflores Mine, Tierra Amarilla, Atacama, Chile (DerHexer) 2012-07-20.jpg|Atacamite from Chile displayed in the Harvard Museum of Natural History Atacamite-168148.jpg|Atacamite from Mt. Gunson, South Australia

References

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. [http://www.mindat.org/min-406.html Atacamite on Mindat.org]
3. [http://rruff.geo.arizona.edu/doclib/hom/atacamite.pdf Handbook of Mineralogy]
4. [http://www.webmineral.com/data/Atacamite.shtml Atacamite on Webmineral]
5. [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Atacamite Mineralienatlas]
6. (17 April 2025). "Ancient computer's gears may not have been able to turn". New Scientist.
7. "Atacamite – CAMEO".
8. (October 2002). "High abrasion resistance with sparse mineralization: copper biomineral in worm jaws". Science.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::