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). It is a secondary copper phosphate mineral found in the oxidized zone of copper ore deposits. The phosphate is often derived from the weathering of apatite and other rock-forming phosphates such as monazite and xenotime. This mineral is sporadically available from the Congo but is exceptionally rare and very collectible!