Formula: Cu₃(PO₄)(OH)₃

Species: Phosphates

Colour: Dark blue to green-blue; green-blue in transmitted light.

Lustre: Vitreous

Hardness: 4½

Specific Gravity: 4.10

Crystal System: Orthorhombic

Name: Named in honor of Mr. Jules Cornet (1865-1929), Belgian geologist. He prospected in the Congo and particularly in Katanga where he discovered its immense mineral wealth.

Type Locality:  L’Etoile du Congo Mine, Lubumbashi, Haut-Katanga, DR Congo