Libethenite is a rare copper phosphate hydroxide mineral. It forms striking, dark green orthorhombic crystals. It is a secondary copper phosphate mineral found in the oxidized zone of copper ore deposits. It is an olive green orthorhombic mineral consisting of a basic copper phosphate and occurring in small prismatic crystals or in globular or reniform masses. It was discovered in 1823 in Ľubietová, Slovakia and is named after the German name of that locality (Libethen).
- Category: Phosphate minerals
- Formula: Cu2PO4OH
- Crystal system: Orthorhombic
- Crystal class: Dipyramidal (mmm)
- Color: Light to dark green, blackish green, olive-green.
Libethenite almost always takes the form of dark-green orthorhombic crystals. It is often found in clusters with other libethenite crystals. It is a rare secondary copper mineral that is noted for its deep green color. It is found in deeply weathered, highly concentrated copper sulfide ore bodies.
- Crystal habit: Globular, druzy, slender prismatic
- Cleavage: Indistinct on  and 
- 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 (-)
Libethenite is found in the oxidized zone of copper ore deposits. It is most often formed from the weathering of phosphate rocks such as apatite, monazite, and xenotime. There have been no confirmed findings of primary libethenite, although a probable case has been reported.
Occurrences – An uncommon secondary mineral in the oxidized zone of copper deposits
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.
Typically found in small amounts in Slovakia, England, Russia, Portugal, Zambia, the Democratic Republic of the Congo, Australia, the United States, and Chile, among others.