Dioptase

Object/Artifact

-

Crater Rock Museum

Name/Title

Dioptase

Entry/Object ID

78.63.44

Description

Chemical Composition: CaCO3 Crystal System: Hexagonal System Description: Common Name: Dioptase Group Name: Silicates Chemistry: CuSiO3 -H2O Location: Tsumeb, Namibia Description: Large and small deep green crystals on a rusty red and pale blue matrix. Physical Description: 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 include stubby crystals that are usually well formed prisms topped with the three faces of a rhombohedon. Prisms are six sided and usually not very long. 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 are also seen. • 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, Nambia; Zaire; Russia; California and Arizona, USA and Chile. • Best Field Indicators are crystal habit, deep color and hardness. Fracture: conchoidal Hardness: 3 Calcite Luster: Vitreous Rock Type: Sedimentary Specific Gravity: 2.7 Streak: white

Collection

Delmar Smith Mineral Collection

Dimensions

Height

2-7/8 in

Width

1 in

Length

1-1/4 in

Dimension Notes

Dimension taken at widest points

Location

Location

Display Case

FS-11

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Permanent