A secondary mineral, with the formula Cu(UO2)2 (PO4)2. 8–12H2O; sp. gr. 3.2; hardness 2.5; tetragonal; normally bright emerald-green, but occasionally dark green; pale green streak; vitreous lustre; crystals tabular, square, foliated, scaly aggregates; cleavage perfect basal {001}; occurs in the oxidized zones of veins containing uranium and copper minerals, often with autunite.