A lovely bright Dioptase Crystals. This mineral always attracts comments for its vivid and natural colour. Large well formed deep green Crystals make this specimen worth collecting. A super piece and collectors favourite.
Altyn, Tyube, Kazakhstan.
2.5cm x 3.9cm x 4.2cm, 33g.
Hydrated copper silicate.
Dioptase Crystals are very beautiful minerals and is one of the few that can challenge emerald’s deep green. The mineral specimens that Dioptase produces are truly a treasure for anyone that likes deep green colours. The faces of the rhombohedrons, and even the prism faces, are very reflective due to a fairly high luster. Crystals can be quite clear but at times they seem to be cloudy due to the deep color.
Dioptase is one of the few silicates to crystallise in the same symmetry class as Dolomite. It forms crystals that can have a typical carbonates Rhombohedral shape. Dioptase shares this symmetry with the typically ice clear silicate Phenakite and the fluorescent but rarely well crystallized Willemite. Surely the brightest most spectacular green in the mineral kingdom. Formation environment in the oxidation zone of copper deposits, in cavities of massive copper minerals
Color is deep green.
Luster is vitreous.
Transparency crystals are transparent to translucent.
Crystal System is trigonal; bar 3 (Dioptase is one of the few rhombic silicates).
Crystal Habits stubby crystals, well formed prisms topped with the three faces of a Rhombohedron. Short six sided and Prisms. Simple rhombohedrons are also common. At times a second rhombohedron will modify the primary rhombohedron faces producing a second set of three smaller faces. Crusts and massive forms too.
Cleavage is perfect in three directions forming rhombohedrons.
Fracture is conchoidal and brittle.
Hardness is 5 (harder than other green copper minerals).
Specific Gravity is approximately 3.3+ (slightly above average)
Streak is green.
Associated Minerals are dolomite, calcite, cerussite, limonite, chrysocolla and other copper minerals.
Other Characteristics: index of refraction is 1.65 – 1.71.
Notable Occurrences include Tsumeb, Namibia; Zaire; Russia; California and Arizona, USA and Chile.
Best Field Indicators are crystal habit, deep color and hardness.