What is Libethenite?
Libethenite is a deep green copper phosphate from oxidised ore deposits, admired for sharp crystals and its place in classic secondary copper assemblages.
Mineralogy and crystal structure
Reference formula: Cu2PO4OH. Libethenite is an orthorhombic copper phosphate hydroxide and is closely associated with pseudomalachite, sampleite and other secondary phosphates. Its strong green colour is attractive but should be interpreted alongside crystal form and paragenesis. Libethenite is classified with phosphates and has a orthorhombic crystal system. Typical hardness is 4–4.5 on the Mohs scale and specific gravity is approximately 3.9–4.1.
Colour, lustre and habit
Typical colours include green, dark green, olive-green, black-green. The usual prismatic, botryoidal, granular habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Libethenite forms in or is associated with oxidised copper deposits and phosphate-rich zones above primary sulfide ores. Important documented localities include Slovakia, Namibia, the United States, Australia, France and Germany.
Deep green geometry from an oxidised copper zone
Libethenite combines the colour appeal of copper minerals with unusually crisp small crystals. A good specimen shows how phosphate-bearing groundwater can reorganise a copper deposit into a new generation of collector minerals.
Collecting and care
Protect crystals from scratches and acids; avoid dust from broken material and keep the specimen labelled as copper-bearing.
