Malachite
Malachite is Cu2(CO3)(OH)2: hardness 3.5 to 4, density 4.05, pale green streak. Of 29 green copper sheets in our set, only its colour field records banding.
Malachite is copper carbonate hydroxide, Cu2(CO3)(OH)2, grandfathered by the IMA: monoclinic, hardness 3.5 to 4, measured density 4.05, pale green streak, perfect {-201} cleavage. It is usually botryoidal and radially fibrous inside. Of 29 green copper sheets in this site's reference set, only malachite's colour line records banding.
In short
- The identity card: Cu2(CO3)(OH)2, monoclinic, hardness 3.5 to 4, density 4.05(2), streak pale green. The Handbook of Mineralogy sheet describes it as typically stalactitic, mammillary, botryoidal, radially fibrous internally, with crystals to 9 cm.
- The banding rule. Of the 176 sheets in this site's reference set, 43 have copper in the header formula and 29 of those list green in the Color field. Only malachite's Color field records banding: commonly banded in masses. Across all 176, four Color fields mention banding.
- Worked composition: 57.48% copper by mass; as oxides CuO 71.95%, CO2 19.90% and H2O 8.15%, exactly the sheet's ideal column. The Elba analysis recalculates to Cu1.99 per carbonate.
- The most-named copper mineral in the set. Malachite is in the Association field of 30 other sheets, more than any other copper-bearing species name in the set. Azurite follows at 18 and chalcopyrite at 17.
- Localities with large crystals on the sheet: the Mashamba West mine in Katanga, Congo, and the Onganja mine, Namibia. Large pure masses came formerly from the mines around Nizhni Tagil and Ekaterinburg in the Urals.
| Species | Formula (Handbook) | Banding in the Color field | Streak | Hardness | Density (measured) | Lustre |
|---|---|---|---|---|---|---|
| Malachite | Cu2(CO3)(OH)2 | Commonly banded in masses | Pale green | 3.5 to 4 | 4.05 | Adamantine to vitreous; silky if fibrous; dull to earthy if massive |
| Pseudomalachite | Cu5(PO4)2(OH)4 | None | Pale green to pale bluish green | 4.5 to 5 | 4.15 to 4.35 | Vitreous to resinous |
| Brochantite | Cu4(SO4)(OH)6 | None | Pale green | 3.5 to 4 | 3.97 | Vitreous, somewhat pearly on cleavages |
| Atacamite | Cu2Cl(OH)3 | None | Apple-green | 3 to 3.5 | 3.745 to 3.776 | Adamantine to vitreous |
| Libethenite | Cu2(PO4)(OH) | None | Not printed | 4 | 3.97 | Vitreous, greasy on fracture |
| Dioptase | CuSiO3·H2O | None | Green | 5 | 3.28 to 3.35 | Vitreous |
| Rosasite | (Cu,Zn)2(CO3)(OH)2 | None | Not printed | 4.5 | 4.0 to 4.2 | Not printed |
| Aurichalcite | (Zn,Cu)5(CO3)2(OH)6 | None | Not printed | 1 to 2 | 3.96 | Silky to pearly |
What is malachite?
Malachite is Cu2(CO3)(OH)2, a copper carbonate with hydroxyl. The Handbook and the September 2026 IMA-CNMNC Master List write the formula the same way. The IMA list records it as grandfathered, with the year printed as a question mark and the country as unknown. The name is from the Greek for mallow, in allusion to its green color.
It is monoclinic, point group 2/m, space group P21/a. Crystals are acicular to prismatic, thick tabular, equant, with {100}, {010}, {001}, {110} and {-201} among the forms, rounded, in sprays and crude composite aggregates, to 9 cm. The usual habit is the massive one: stalactitic, mammillary, botryoidal, and radially fibrous internally. Twins are very common, as contact or penetration twins, and also polysynthetic.
Hardness 3.5 to 4, measured density 4.05(2), calculated 3.983. Cleavage is perfect on {-201} and fair on {010}; the {-201} was read from the rendered sheet, because text extraction drops the bar. Colour is bright green, dark green or blackish green, commonly banded in masses. The streak is pale green and the lustre adamantine to vitreous, silky if fibrous, dull to earthy if massive. Why a massive piece can look dull from new is on why is my malachite dull.
How do you recognise malachite? The banding rule
Method. For the 176 sheets in this site's reference set, the header formula and the Color field were read from the pdftotext -layout text. Copper appears in 43 formulas. Of those, 29 list green in the Color field (case-insensitive), from antlerite and atacamite to torbernite and turquoise. The Color field was then searched for band. It matches on four sheets of the 176: goethite, hydrozincite, rhodochrosite and malachite. Of the 29 green copper sheets, malachite is the only one. Neither search word contains a ligature.
The rule: green, banded in the mass, with a pale green streak and hardness 3.5 to 4, is malachite until shown otherwise. The table sets the look-alikes against it. Pseudomalachite, named for the resemblance, is harder at 4.5 to 5 and has a vitreous to resinous lustre. Brochantite matches the hardness and streak but not the banding. Atacamite has an apple-green streak.
What the rule does not do is catch imitations. Dyed stone, resin and reconstituted material can be banded too, and a density reading is the test that exposes them. That is covered on how to tell if malachite is real, which uses the same sheet figures, and on how to tell if a crystal is dyed. The botryoidal habit is explained on what does botryoidal mean.
What is malachite made of? A worked composition
On standard atomic weights, Cu2(CO3)(OH)2 has a formula mass of 221.114: 57.48% copper. As oxides it is CuO 71.95%, CO2 19.90%, H2O 8.15%, which is exactly the sheet's ideal column (2).
The analysed specimen is from Rio Marina, Elba, Italy: CO2 20.04%, CuO 72.03%, H2O 8.09%, total 100.16%. Set to one carbonate, that is Cu1.989 and H2O 0.986, equivalent to (OH)1.97. Elba malachite, in other words, sits within about 1.5% of the ideal formula on every component.
Against azurite, the other copper carbonate: azurite is Cu3(CO3)2(OH)2, 55.31% copper, with CuO 69.24%, CO2 25.54% and H2O 5.23% on the same method. The two differ in the ratio of copper to carbonate, 2 to 1 against 3 to 2. By hand they differ in colour and streak, pale green against pale blue, and density, 4.05 against 3.773. What the copper content means for handling is not this page's subject; see the FAQ.
Why does malachite occur with so many other copper minerals?
The sheet's occurrence line: a common secondary mineral formed in the oxidation zone of copper deposits; locally may be an ore of copper. Its own associates are azurite, cuprite, cerussite, chrysocolla, calcite and “limonite”.
Method. Each of the 176 species names in the set was searched as a whole word in the Association fields of the other 175 sheets (the same run as on the calcite page). Malachite appears on 30 sheets, fourth of all 176 names after calcite (60), quartz (50) and pyrite (31). Among the names with copper in their formula it is first: azurite 18, chalcopyrite 17, chrysocolla 14, brochantite 13. The 30 include azurite, brochantite, dioptase, rosasite, aurichalcite, conichalcite, olivenite, libethenite and native copper.
So a malachite label says something about the rest of the specimen: an oxidised copper zone. The copper species are indexed at the species index.
Where malachite is found
The Handbook says many localities; some for abundant and rich material include, then, in order: Chessy, near Lyon, France; large pure masses formerly from mines around Nizhni Tagil and Ekaterinburg in the Urals, Russia; in Katanga, Congo, Lubumbashi, the Musonoi mine near Kolwezi, and large crystals from the Mashamba West mine; in Namibia, Tsumeb, and large crystals at the Onganja mine, 60 km northeast of Windhoek; in Australia, Broken Hill and Cobar, New South Wales, and Burra, South Australia; in the USA, the Copper Queen, Czar and other mines at Bisbee and Morenci, Arizona, and the Fierro-Hanover district and Santa Rita, New Mexico.
The sheet names no British locality. That is a statement about the sheet, not about Britain. The locality pages are Tsumeb and Broken Hill. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.