Caledonite | |
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General | |
Category | Sulfate minerals |
Formula (repeating unit) | Cu2Pb5(OH)6CO3(SO4)3 |
IMA symbol | Cdo[1] |
Strunz classification | 7.BC.50 |
Crystal system | Orthorhombic |
Crystal class | Pyramidal (mm2) (same H-M symbol) |
Space group | Pmn21 |
Unit cell | a = 20.089(7) Å, b = 7.146(3) Å, c = 6.56 Å; Z = 2 |
Identification | |
Color | Blue; green |
Crystal habit | Typically striated prismatic or tabular crystals; radial aggregates |
Cleavage | [001] perfect; [100] distinct |
Fracture | Uneven |
Tenacity | Brittle |
Mohs scale hardness | 2.5–3 |
Luster | Vitreous |
Streak | Green-white; blue-green |
Diaphaneity | Transparent to translucent |
Specific gravity | 5.6–5.8 |
Optical properties | Biaxial (−) |
Refractive index | nα = 1.818(3) nβ = 1.866(3) nγ = 1.909(3) |
Birefringence | δ = 0.091 |
Pleochroism | Weak |
2V angle | Measured: 85° |
References | [2][3][4][5] |
Caledonite, whose name derives from Caledonia, the historical name of its place of discovery (Scotland), is a richly colored blue-green sulfate-carbonate mineral of lead and copper with an orthorhombic crystal structure. It is an uncommon mineral found in the oxidized zones of copper-lead deposits.