Diaspore
Species
Uncommon · AlO(OH)
Aluminium oxide hydroxide like boehmite but much harder, the third main mineral of bauxite, formed as bauxites are buried and altered, and also in emery and marble with corundum. Its name, from the Greek "to scatter", recalls how it bursts into pearly scales in a flame. It can turn from brownish green in daylight to pink in artificial light; gem diaspore from the İlbir Mountains of southwest Turkey is sold under trade names such as zultanite and csarite.
Identity
- Formula
- AlO(OH)
- Chemical class
- Oxide
- Also known as
- Zultanite (trade name, gem), Csarite (trade name, gem)
- Ore of
- Aluminum
Crystallography
- Crystal system
- Orthorhombic
- Habits
- Tabular, Acicular, Foliated, Massive
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 6.5
- Density
- 3.38 g/cm³
- Luster
- Vitreous, Adamantine, Pearly
- Colors
- white, pale gray, colorless, greenish gray, brown, pale yellow, pink
- Transparency
- Transparent, Translucent
Geology
- Origins
- Sedimentary, Metamorphic, Hydrothermal
- Host rocks
- Marble
- Associated minerals
- Corundum, Magnetite, Spinel, Chlorite, Gibbsite, Boehmite, Hematite
- Found in
- Bauxite, Laterite, Lateritic deposit
- Geography
- Russia (Mramorsk, Kossoi Brod, Urals), Turkey (Aydın, Muğla), Greece (Naxos, Samos), Slovakia (Banská Štiavnica), USA (Chester, Massachusetts), South Africa (Postmasburg)
Classification
- Rarity
- Uncommon
- 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, Diaspore. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Diaspore. Wikipedia.
- Bauxite. Wikipedia.
Browse the Crystal Encyclopedia — MGS Toolbox