CornetiteCornetite is a phosphate of copper with hydroxyl, named after the geologist. It was discovered in 1917.Type localityCornetite is most notably found in the Star of Congo mine, near Lubumbashi.EnvironmentCornetite is a rare secondary mineral in some hydrothermal copper deposits.StructureUnlike related phases such as pseudomalachite, the copper atoms are all five-fold coordinated by oxygen. There are three unique copper sites that are all quite distorted from ideal symmetry. Two are in approximate tetragonal pyramids and the third is essentially a trigonal bipyramidal coordination. Edge sharing polyhedra lead to copper-copper dimer formation, and the overall structure is a three-dimensional network of copper-oxygen polyhedra.