Libethenite

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Libethenite
Libethenite-tuc1033a.jpg
General
Category Phosphate minerals
Formula
(repeating unit)
Cu2PO4OH
Strunz classification 8.BB.30
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Pnnm
Identification
Color Light to dark green, blackish green, olive-green
Crystal habit Globular, druzy, slender prismatic
Cleavage Indistinct on [100] and [010]
Fracture Irregular, uneven to conchoidal
Tenacity Brittle
Mohs scale hardness 4
Luster Vitreous, greasy
Streak light green
Specific gravity 3.6 - 4, Average = 3.8
Optical properties Biaxial (-)
Refractive index nα = 1.701 - 1.704 nβ = 1.743 - 1.747 nγ = 1.787 - 1.790
References [1][2]

Libethenite is a rare copper phosphate hydroxide mineral. It forms striking, dark green orthorhombic crystals. It was discovered in 1823 in Ľubietová, Slovakia and is named after the German name of that locality (Libethen).[1][2] Libethenite has also been found in the Miguel Vacas Mine, Conceição, Vila Viçosa, Évora District, Portugal, and in Tier des Carrières, Cahai, Vielsaim, Stavelot Massif, Luxembourg Province, Belgium.[2]

Appearance[edit]

Libethenite almost always takes the form of dark-green orthorhombic crystals.[1][2] It is often found in clusters with other libethenite crystals.

Formation[edit]

Libethenite is found in the oxidized zone of copper ore deposits.[2] It is most often formed from the weathering of phosphate rocks such as apatite, monazite, and xenotime.[2] There have been no confirmed findings of primary libethenite, although a probable case has been reported.[2]

References[edit]

Detail of gemmy, emerald-green, orthorhombic libethenite microcrystals on malachite, from the type locality, Ľubietová, Slovakia. See File:Libethenite-258236.jpg for the full specimen.