Atacamite
A valid IMA mineral species - grandfathered
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About Atacamite
Atacama Desert
Formula:
Cu2(OH)3Cl
Colour:
Bright green, dark emerald-green to blackish green; shades of green in transmitted light.
Lustre:
Adamantine, Vitreous
Hardness:
3 - 3½
Specific Gravity:
3.745 - 3.776
Crystal System:
Orthorhombic
Member of:
Name:
Named in 1802 by Dmitri de Gallitzin after the type locality, in the Atacama Desert of northern Chile.
Type Locality:
Polymorph of:
Atacamite Group.
A secondary copper mineral formed through the oxidation of other copper minerals, especially in arid, saline conditions. May be confused with brochantite.
May alter to malachite and chrysocolla, creating pseudomorphs.
A secondary copper mineral formed through the oxidation of other copper minerals, especially in arid, saline conditions. May be confused with brochantite.
May alter to malachite and chrysocolla, creating pseudomorphs.
Unique Identifiers
Mindat ID:
406
Long-form identifier:
mindat:1:1:406:6
IMA Classification of Atacamite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Cu2+2Cl(OH)3
Classification of Atacamite
3.DA.10a
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
A : With Cu, etc., without Pb
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
A : With Cu, etc., without Pb
Dana 7th ed.:
10.1.1.1
10.1.1.1
10 : OXYHALIDES AND HYDROXYHALIDES
1 : A2(O,OH)3Xq
10 : OXYHALIDES AND HYDROXYHALIDES
1 : A2(O,OH)3Xq
8.2.4
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
2 : Halides of Cu
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
2 : Halides of Cu
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Ata | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Atacamite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Atacamite
Adamantine, Vitreous
Transparency:
Transparent, Translucent
Colour:
Bright green, dark emerald-green to blackish green; shades of green in transmitted light.
Streak:
Apple-green.
Hardness:
3 - 3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
On {010}, fair on {101}.
On {010}, fair on {101}.
Fracture:
Conchoidal
Density:
3.745 - 3.776 g/cm3 (Measured) 3.756 g/cm3 (Calculated)
Optical Data of Atacamite
Type:
Biaxial (-)
RI values:
nα = 1.831 nβ = 1.861 nγ = 1.88
2V:
Calculated: 74°
Max. Birefringence:
δ = 0.049
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r < v, strong
Pleochroism:
Weak
Comments:
X = pale green, Y = yellow-green, Z = grass-green; Orientation: X = b, Y = a, Z = c.
Chemistry of Atacamite
Mindat Formula:
Cu2(OH)3Cl
Element Weights:
Elements listed:
Common Impurities:
Ca,Co
Crystallography of Atacamite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pnma
Cell Parameters:
a = 6.03 Å, b = 9.12 Å, c = 6.865 Å
Ratio:
a:b:c = 0.661 : 1 : 0.753
Unit Cell V:
377.53 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Slender crystals, to 10 cm, prismatic along [001]; striated parallel to [001], on {010} parallel to [110]; commonly tabular perpendicular to {010} or pseudo-octahedral with {110} and {011}. Also fibrous, sandy granular to compact, massive.
Twinning:
Rare, with twin and composition plane {110}; more common about [544]. Doublets, triplets, both contact and penetration, and complex groups result from twinning.
Crystallographic forms of Atacamite
Crystal Atlas:
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Atacamite no.4 - {110} - Goldschmidt (1913-1926)
Atacamite no.9 - {110} - Goldschmidt (1913-1926)
Atacamite no.25 - {110} - Goldschmidt (1913-1926)
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0019936 | Atacamite | Zheng X G, Mori T, Nishiyama K, Higemoto W, Yamada H, Nishikubo K, Xu C N (2005) Antiferromagnetic transitions in polymorphous minerals of the natural cuprates atacamite and botallackite Cu2Cl(OH)3 Physical Review B - Condensed Matter 71 174404-8 | 2005 | synthetic | 0 | 293 | |
| 0010032 | Atacamite | Parise J B, Hyde B G (1986) The structure of atacamite and its relationship to spinel Acta Crystallographica C42 1277-1280 |  | 1986 | Mina La Farola, Chile | 0 | 293 |
| 0009136 | Atacamite | Wells A F (1949) The crystal structure of atacamite and the crystal chemistry of cupric compounds Acta Crystallographica 2 175-180 | | 1949 | 0 | 293 |
CIF Raw Data - click here to close
Epitaxial Relationships of Atacamite
Epitaxial Minerals:
| 'Clinoatacamite' | Cu2(OH)3Cl |
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.48 Å | (100) |
| 5.03 Å | (70) |
| 2.278 Å | (69) |
| 1.6060 Å | (57) |
| 2.759 Å | (55) |
| 2.836 Å | (51) |
| 2.779 Å | (51) |
Locality:
Comments:
Recorded on material from Inca de Oro, Copiapó, Chile.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 15 : Black/white smoker minerals and other seafloor hydrothermal minerals | |
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] | |
| 47a : [Near-surface hydration of prior minerals] | |
| 47g : [Halogen-bearing surface weathering minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 49 : Oxic cellular biomineralization (see also #44) | <0.54 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) | |
| 57 : Other minerals formed by human processes |
Geological Setting:
An oxidation product of other copper minerals, especially under arid, saline conditions; in fumarolic deposits; a weathering product of sulphides in submarine black smoker deposits; an alteration product of bronze and copper objects of antiquity.
Type Occurrence of Atacamite
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, USA (No. 110816)
Geological Setting of Type Material:
An oxidation product of other copper minerals under arid conditions
Synonyms of Atacamite
Other Language Names for Atacamite
Relationship of Atacamite to other Species
Member of:
Other Members of Atacamite Group:
| Botallackite | Cu2(OH)3Cl | Mon. 2/m : P21/m |
| Clinoatacamite | Cu2(OH)3Cl | Mon. 2/m |
| Gillardite | Cu3Ni(OH)6Cl2 | Trig. 3m(32/m) : R3m |
| Haydeeite | Cu3Mg(OH)6Cl2 | Trig. 3m(32/m) : P3m1 |
| Herbertsmithite | Cu3Zn(OH)6Cl2 | Trig. 3m(32/m) : R3m |
| Hibbingite | Fe2+2(OH)3Cl | Orth. mmm(2/m2/m2/m) : Pnma |
| Iyoite | MnCuCl(OH)3 | Mon. 2/m : P21/m |
| Kapellasite | Cu3Zn(OH)6Cl2 | Trig. 3m(32/m) : P3m1 |
| Kempite | Mn2+2(OH)3Cl | Orth. mmm(2/m2/m2/m) : Pnma |
| Kuliginite | Fe3Mg(OH)6Cl2 | Trig. 3 : R3 |
| Leverettite | Cu3Co(OH)6Cl2 | Trig. 3 : R3 |
| Misakiite | Cu3Mn(OH)6Cl2 | Trig. 3m(32/m) : P3m1 |
| Paratacamite | Cu3(Cu,Zn)(OH)6Cl2 | Trig. 3 : R3 |
| Paratacamite-(Mg) | Cu3(Mg,Cu)(OH)6Cl2 | Trig. 3 : R3 |
| Paratacamite-(Ni) | Cu3(Ni,Cu)(OH)6Cl2 | Trig. 3 : R3 |
| Tondiite | Cu3Mg(OH)6Cl2 | Trig. 3m(32/m) : R3m |
| 'Unnamed (Cu-Zn Chloride Hydroxide)' | CuZnCl(OH)3 | Mon. 2/m : P21/m |
Common Associates
Associations Based on Photo Data:
| 197 photos of Atacamite associated with Chrysocolla | Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O, x < 1 |
| 150 photos of Atacamite associated with Halloysite | Al2Si2O5(OH)4 · n(H2O) |
| 107 photos of Atacamite associated with Quartz | SiO2 |
| 101 photos of Atacamite associated with Libethenite | Cu2(PO4)(OH) |
| 92 photos of Atacamite associated with Gypsum | CaSO4 · 2H2O |
| 78 photos of Atacamite associated with Malachite | Cu2(CO3)(OH)2 |
| 62 photos of Atacamite associated with Pseudomalachite | Cu5(PO4)2(OH)4 |
| 45 photos of Atacamite associated with Brochantite | Cu4(SO4)(OH)6 |
| 43 photos of Atacamite associated with Cuprite | Cu2O |
| 30 photos of Atacamite associated with Paratacamite | Cu3(Cu,Zn)(OH)6Cl2 |
Related Minerals - Strunz-mindat Grouping
| 3.DA. | Parahibbingite | Fe2(OH)3Cl |
| 3.DA. | Centennialite | CaCu3Cl2(OH)6 · nH2O (n ~ 0.7) |
| 3.DA. | Bounahasite | Cu+Cu2+2(OH)3Cl2 |
| 3.DA. | Muonionalustaite | Ni3(OH)4Cl2 · 4H2O |
| 3.DA.05 | Melanothallite | Cu2Cl2O |
| 3.DA.10c | Haydeeite | Cu3Mg(OH)6Cl2 |
| 3.DA.10b | Clinoatacamite | Cu2(OH)3Cl |
| 3.DA.10c | Paratacamite | Cu3(Cu,Zn)(OH)6Cl2 |
| 3.DA.10c | Kapellasite | Cu3Zn(OH)6Cl2 |
| 3.DA.10c | Leverettite | Cu3Co(OH)6Cl2 |
| 3.DA.10a | Hibbingite | Fe2+2(OH)3Cl |
| 3.DA.10c | Paratacamite-(Ni) | Cu3(Ni,Cu)(OH)6Cl2 |
| 3.DA.10a | Kempite | Mn2+2(OH)3Cl |
| 3.DA.10c | Tondiite | Cu3Mg(OH)6Cl2 |
| 3.DA.10b | Belloite | Cu(OH)Cl |
| 3.DA.10c | Misakiite | Cu3Mn(OH)6Cl2 |
| 3.DA.10b | Iyoite | MnCuCl(OH)3 |
| 3.DA.10c | Kuliginite | Fe3Mg(OH)6Cl2 |
| 3.DA.10c | Gillardite | Cu3Ni(OH)6Cl2 |
| 3.DA.10b | 'Unnamed (Cu-Zn Chloride Hydroxide)' | CuZnCl(OH)3 |
| 3.DA.10b | Botallackite | Cu2(OH)3Cl |
| 3.DA.10c | Herbertsmithite | Cu3Zn(OH)6Cl2 |
| 3.DA.15 | Claringbullite | Cu4ClF(OH)6 |
| 3.DA.15 | Barlowite | Cu4BrF(OH)6 |
| 3.DA.20 | Simonkolleite | Zn5Cl2(OH)8 · H2O |
| 3.DA.25 | Buttgenbachite | Cu19(NO3)2(OH)32Cl4 · 2H2O |
| 3.DA.25 | Connellite | Cu19(SO4)(OH)32Cl4 · 3H2O |
| 3.DA.30 | Abhurite | Sn21Cl16(OH)14O6 |
| 3.DA.35 | Ponomarevite | K4Cu4Cl10O |
| 3.DA.40 | Calumetite | CaCu4(OH)8Cl2 · 3.5H2O |
| 3.DA.40 | Anthonyite | Cu(OH,Cl)2 · 3H2O |
| 3.DA.45 | Khaidarkanite | Cu4Al3(OH)14F3 · 2H2O |
| 3.DA.50 | Bobkingite | Cu5Cl2(OH)8 · 2H2O |
| 3.DA.55 | Avdoninite | K2Cu5(OH)4Cl8 · H2O |
| 3.DA.60 | Droninoite | Ni6Fe3+2(OH)16Cl2 · 4H2O |
| 3.DA.70 | Chrysothallite | K6Cu6Tl3+Cl17(OH)4 · H2O |
| 3.DA.70 | Dioskouriite | CaCu4Cl6(OH)4 · 4H2O |
| 3.DA.75 | Feodosiyite | Cu11Mg2Cl18(OH)8 · 16H2O |
| 3.DA.80 | Romanorlovite | K8Cu6Cl17(OH)3 |
Other Information
Notes:
Readily soluble in acids.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Ore of copper.
Internet Links for Atacamite
mindat.org URL:
https://www.mindat.org/min-406.html
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References for Atacamite
Reference List:
Haüy, René Just (1801) Traité de Minéralogie (1st ed.) Vol. 3. Chez Louis, Paris. as Cuivre muriaté
Hausmann, Johann Friedrich Ludwig (1813) Handbuch der Mineralogie (1st ed.). Vandenhoeck und Ruprecht. p.1039 - as Smaragdochalcit
Lévy, Armand (1838) Description d'une collection de minéraux, formée par m. Henri Heuland, et appartenant à m. C.H. Hampden Turner, de Rooksnest, dans le comté de Surrey en Angleterre. Tome Troisiéme Vol. 3. F. Richter et Haas. 475 pp. p.47
Brooke, Henry J., Phillips, William (1852) An Elementary Introduction to Mineralogy (6th ed.) as Remolinite
Ford, W. E. (1911) Über einige bemerkenswerte Zwillinge von Atacamit und einige andere Kupfermineralien von Collahurasi, Provinz Tarapacá, Chile. Zeitschrift für Kristallographie, 48 (1-6). 454-463 doi:10.1524/zkri.1911.48.1.454
Wells, A. F. (1949) The crystal structure of atacamite and the crystal chemistry of cupric compounds. Acta Crystallographica, 2 (3) 175-180 doi:10.1107/s0365110x49000461
Sharkey, J. B., Lewin, S. Z. (1971) Conditions governing the formation of atacamite and paratacamite. American Mineralogist, 56 (1-2) 179-192
Bailey, S. W. (1977) Report of the I.M.A.-I. U.Cr. Joint Committee on Nomenclature. American Mineralogist, 62 (5-6) 411-415
Parise, J. B., Hyde, B. G. (1986) The structure of atacamite and its relationship to spinel. Acta Crystallographica Section C Crystal Structure Communications, 42 (10) 1277-1280 doi:10.1107/s0108270186092570
Pollard, A. M., Thomas, R. G., Williams, P. A. (1989) Synthesis and stabilities of the basic copper(II) chlorides atacamite, paratacamite and botallackite. Mineralogical Magazine, 53 (373) 557-563 doi:10.1180/minmag.1989.053.373.06
Frost, Ray L., Martens, Wayde, Kloprogge, J. Theo, Williams, Peter A. (2002) Raman spectroscopy of the basic copper chloride minerals atacamite and paratacamite: implications for the study of copper, brass and bronze objects of archaeological significance. Journal of Raman Spectroscopy, 33 (10). 801-806 doi:10.1002/jrs.921
Martens, Wayde, Frost, Ray L., Williams, Peter A. (2003) Raman and infrared spectroscopic study of the basic copper chloride minerals – implications for the study of the copper and brass corrosion and "bronze disease". Neues Jahrbuch für Mineralogie - Abhandlungen, 178 (2) 197-215 doi:10.1127/0077-7757/2003/0178-0197
Zheng, X. G., Mori, Takashi, Nishiyama, Kusuo, Higemoto, Wataru, Yamada, Hiroshi, Nishikubo, Keiko, Xu, C. N. (2005) Antiferromagnetic transitions in polymorphous minerals of the natural cuprates atacamite and botallackiteCu2Cl(OH)3. Physical Review B, 71 (17) doi:10.1103/physrevb.71.174404
Krivovichev, Sergey V., Hawthorne, Frank C., Williams, Peter A. (2016) Structural complexity and crystallization: the Ostwald sequence of phases in the Cu2(OH)3Cl system (botallackite–atacamite–clinoatacamite). Structural Chemistry, 28 (1). 153-159 doi:10.1007/s11224-016-0792-z
Heinze, L.; Kotte, T.; Rausch, R.; Demuer, A.; Luther, S.; Feyerherm, R.; Ammerlaan, E. L. Q. N.; Zeitler, U.; Gorbunov, D. I.; Uhlarz, M.; et al. (2025) Atacamite Cu 2 Cl ( OH ) 3
Localities for Atacamite
Showing 729 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
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Lily Mine, Humay District, Pisco Province, Ica, Peru