Dioptase
Species
Rare · CuSiO₃·H₂O
Hydrated copper silicate forming vivid emerald-green crystals in the oxidised zones of copper deposits. Despite its intense colour, its softness and perfect cleavage make it fragile as a gemstone. Valued as a collector mineral; its name, from the Greek for seeing through, refers to the cleavages visible inside clear crystals.
Identity
- Formula
- CuSiO₃·H₂O
- Chemical class
- Silicate
- Also known as
- Emerald copper (archaic)
Crystallography
- Crystal system
- Trigonal
- Habits
- Prismatic, Rhombohedral
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 5
- Density
- 3.28 g/cm³
- Luster
- Vitreous
- Colors
- dark green, blue-green, green
- Streak
- green
- Transparency
- Transparent, Translucent
Geology
- Origins
- Sedimentary, Hydrothermal
- Associated minerals
- Malachite, Chrysocolla, Cerussite, Wulfenite
- Found in
- Oxidized zone (gossan)
- Geography
- Namibia, Kazakhstan, DR Congo, USA, Chile
Classification
- Rarity
- Rare
- Gem quality
- Yes
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Dioptase. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Dioptase. Gemdat.org (Hudson Institute of Mineralogy).
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