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Malachite

This page kindly sponsored by Norman King
Formula:
Cu2(CO3)(OH)2
System:
Monoclinic
Colour:
Bright green, with ...
Hardness:
3½ - 4
Name:
Named in antiquity (see Pliny the Elder, 79 CE) molochitus after the Greek μαλαχή, "mallows," in allusion to the green color of the leaves. Known in the new spelling, malachites, at least by 1661.
Malachite is a green, very common secondary copper mineral with a widely variable habit. Typically it is found as crystalline aggregates or crusts, often banded in appearence, like agates. It is also often found as botryoidal clusters of radiating crystals, and as mammillary aggregates as well. Single crystals and clusters of distinguishable crystals are uncommon, but when found they are typically acicular to prismatic. It is also frequently found as a pseudomorph after Azurite crystals, which are generally more tabular in shape.

Structurally related to the Rosasite Group.

Visit gemdat.org for gemological information about Malachite.

Classification of Malachite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
5.BA.10

5 : CARBONATES (NITRATES)
B : Carbonates with additional anions, without H2O
A : With Cu, Co, Ni, Zn, Mg, Mn
Dana 7th ed.:
16.3.2.1
16a.3.1.1

16a : ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
3 : (AB)2(XO3)Zq
11.2.1

11 : Carbonates
2 : Carbonates of Cu
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Occurrences of Malachite

Geological Setting:
It is the most common secondary mineral found in the oxidized zones of copper deposits.

Physical Properties of Malachite

Adamantine, Vitreous, Silky, Dull, Earthy
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Bright green, with crystals deeper shades of green, even vary dark to nearly black; green to yellowish green in transmitted light.
Streak:
Light green
Hardness (Mohs):
3½ - 4
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {201}, fair on {010}.
Fracture:
Irregular/Uneven, Sub-Conchoidal, Fibrous
Density:
3.6 - 4.05 g/cm3 (Measured)    4 g/cm3 (Calculated)

Crystallography of Malachite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 9.502Å, b = 11.974Å, c = 3.240Å
β = 98.75°
Ratio:
a:b:c = 0.794 : 1 : 0.271
Unit Cell Volume:
V 364.35 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals uncommon, usually short or long prismatic or acicular, parallel to [001]; often grouped in rosettes, sprays, or tufts. Botryoidal to mammillary aggregates of radiating fibrous crystals more common. It may also be massive, compact, and stalactic.
Twinning:
Untwinned crystals are extremely rare. Typically twinned on {100}, sometimes as penetration or polysynthetic twinning with the axis parallel to [201].
Comment:
Space group P21/a.

Crystallographic forms of Malachite

Crystal Atlas:
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Malachite no.17 - Goldschmidt (1913-1926)
Malachite no.20 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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X-Ray Powder Diffraction:
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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction Data:
d-spacingIntensity
5.99(60)
5.06(80)
3.69(90)
2.86(100)
2.82(40)
2.78(50)
2.52(60)
2.46(40)
Comments:
Data given are for synthetic material.

Optical Data of Malachite

Type:
Biaxial (-)
RI values:
nα = 1.655 nβ = 1.875 nγ = 1.909
2V:
Measured: 43° , Calculated: 38°
Max Birefringence:
δ = 0.254
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
relatively weak
Pleochroism:
Visible
Comments:
X ^ c 23½° = nearly colourless
Y b = yellowish green
Z = Deep green

Chemical Properties of Malachite

Formula:
Cu2(CO3)(OH)2
Essential elements:
All elements listed in formula:
Common Impurities:
Zn,Co,Ni

Relationship of Malachite to other Species

5.BA.05AzuriteCu3(CO3)2(OH)2
5.BA.10GeorgeiteCu2(CO3)(OH)2 · 6H2O
5.BA.10Glaukosphaerite(Cu,Ni)2(CO3)(OH)2
5.BA.10Kolwezite(Cu,Co)2(CO3)(OH)2
5.BA.10Mcguinnessite(Mg,Cu)2(CO3)(OH)2
5.BA.10NullaginiteNi2(CO3)(OH)2
5.BA.10PokrovskiteMg2(CO3)(OH)2
5.BA.10Rosasite(Cu,Zn)2(CO3)(OH)2
5.BA.10Zincrosasite(Zn,Cu)2(CO3)(OH)2
5.BA.10ChukanoviteFe22+(CO3)(OH)2
5.BA.15Aurichalcite(Zn,Cu)5(CO3)2(OH)6
5.BA.15HydrozinciteZn5(CO3)2(OH)6
5.BA.20HoldawayiteMn6(CO3)2(OH)7(Cl,OH)
5.BA.25DeferniteCa6(CO3)2-x(SiO4)x(OH)7(Cl,OH)1-2x (x<0.5)
5.BA.25UM1977-03-COSiO:CaClHCa10(SiO4)(CO3)7(Cl,OH)2
5.BA.30Loseyite(Mn2+,Zn,Mg)4Zn3(CO3)2(OH)10
5.BA.30Sclarite(Zn,Mg,Mn2+)4Zn3(CO3)2(OH)10
11.2.2AzuriteCu3(CO3)2(OH)2
11.2.4ChalconatroniteNa2Cu(CO3)2 · 3H2O
11.2.5CallaghaniteCu2Mg2(CO3)(OH)6 · 2H2O

Other Names for Malachite

Other Information

Thermal Behaviour:
Loses water at about 315°, leaving tenorite.
Other Information:
Readily soluble in dilute acids. Very slightly soluble in water containing CO2.

Frequently found as pseudomorphs after azurite, or as alteration pseudomorphs after cuprite. Less frequently occurs as pseudomorphs after atacamite, brochantite, chalcopyrite, tetrahedrite, chalcophyllite, gypsum, libethenite, calcite, sphalerite, cerussite, and pyrite.

Rarely found altered to azurite or cuprite.
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:
A minor ore of copper when abundant enough in a copper deposit.

References for Malachite

Reference List:
Wallerius, J.G (1747) Mineralogia, eller Mineralriket. Stockholm: 279 (as Malachit).

L' Abbé Fontana (1778) Le Journal de physique et le radium, Paris: 2: 509.

Thomson (1836): 1: 601 (as Mysorin).

Zincken (1842) Berg.- und hüttenmännisches Zeitung, Freiberg, Leipzig (merged into Glückauf): 1 (as Kalk-malachit).

Lang (1863) Philosophical Magazine and Journal of Science: 25: 432.

Lang (1864) Philosophical Magazine and Journal of Science: 28: 502.

Des Cloizeaux, A. (1874) Manuel de minéralogie. 2 volumes and Atlas, Paris. volume 2, 1 Fasc., 208pp.: 185.

Haege (1888) Inaugural Dissertation, Jena.

Gonnard (1906) Min. du Rhône et de la Loire, Paris: 82.

Galbraith (1914) Arizona Bureau of Mines, Geological Series Bulletin 149.

Schrader, et al (1917) USGS Bulletin 624.

Goldschmidt, V. (1918) Atlas der Krystallformen. 9 volumes, atlas, and text, vol. 5: 187.

Perrier (1921) Reale accademia nazionale dei Lincei, Rome, Att.: 30[5]: 309.

Shannon (1926) U.S. National Museum, Bulletin 131.

Hintze, Carl (1929) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3A]: 3368.

Guillot and Geneslay (1936) Comptes rendus de l’Académie des sciences de Paris: 202: 136.

Binder (1937) Comptes rendus de l’Académie des sciences de Paris: 204: 1200.

Pabst (1938) California Division of Mines Bulletin 113.

Northrop (1942) University of New Mexico Bulletin, Geology Series: 6, no. 1.

Ramsdell and Wolfe (1950) American Mineralogist: 35: 119.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 252-255.

Acta Crystallographica: 4: 200-204.

Zeitschrift für Kristallographie (1977): 145: 412.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana: 488.

F. Girgsdies and M. Behrens (2012): On the structural relations of malachite. II. The brochantite MDO polytypes. Acta Crystallogr. B68, 571-577.

Internet Links for Malachite

Specimens:
The following Malachite specimens are currently listed for sale on minfind.com.

Localities for Malachite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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