Bremen green
| Malachite | |
|---|---|
Barite (included by malachite) on malachite
|
|
| General | |
| Category | Carbonate mineral |
|
Formula (repeating unit) |
Cu2CO3(OH)2 |
| Strunz classification | 5.BA.10 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/a |
| Identification | |
| Formula mass | 221.1 g/mol |
| Color | Bright green, dark green, blackish green, commonly banded in masses; green to yellowish green in transmitted light |
| Crystal habit | Massive, botryoidal, stalactitic, crystals are acicular to tabular prismatic |
| Twinning | Common as contact or penetration twins on {100} and {201}. Polysynthetic twinning also present. |
| Cleavage | Perfect on {201} fair on {010} |
| Fracture | Subconchoidal to uneven |
| Mohs scale hardness | 3.5–4.0 |
| Luster | Adamantine to vitreous; silky if fibrous; dull to earthy if massive |
| Streak | light green |
| Diaphaneity | Translucent to opaque |
| Specific gravity | 3.6–4 |
| Optical properties | Biaxial (–) |
| Refractive index | nα = 1.655 nβ = 1.875 nγ = 1.909 |
| Birefringence | δ = 0.254 |
| References | |
Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and spaces, deep underground, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare but do occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur.
The stone's name derives (via Latin: molochītis, Middle French: melochite, and Middle English melochites) from Greek Μολοχίτης λίθος molochitis lithos, "mallow-green stone", from μολόχη molōchē, variant of μαλάχη malāchē, "mallow". The mineral was given this name due to its resemblance to the leaves of the mallow plant.
Malachite was extensively mined at the Great Orme mines in Britain 3,800 years ago using stone and bone tools. Archaeological evidence indicates that mining activity ended around 600 B.C.E with up to 1,760 tonnes of copper being produced from the mined Malachite.
Archaeological evidence indicates that the mineral has been mined and smelted to obtain copper at Timna Valley in Israel for over 3,000 years. Since then, malachite has been used as both an ornamental stone and as a gemstone.
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Wikipedia