This dioptase is from the Tsumeb Mine, Tsumeb, Otjikoto Region of Namibia. This is an ore pipe deposit that is mined for copper lead and other metals. It is over 3000 feet deep and contains two oxidation zones. Over 300 mineral species have been identified at the mine including, world class, dioptase. It is a silicate containing the elements Cu, Si, O and H. This specimen consists of a calcite crystal matrix and gemmy dioptase crystals. The calcites crystals have a rhombohedral habit. The dioptase have a bright vitreous luster. The largest crystal measures 9/16 inches or 14 mm long. The piece measures 1 11/16 x 1 1/2 x 7/8 inches or 43 x 38 x 22 mm.