Torbernite is a mineral belonging to the uranyl phosphate group. Its chemical formula is (Cu,U)2(PO4)2·8-12H2O. It typically forms bright green to emerald-green crystals, often with a lustrous or glassy appearance. The vivid coloration is due to its high uranium content. Torbernite is radioactive, and its green coloration can fade upon prolonged exposure to light due to dehydration.