Kyanite
Species
Uncommon · Al₂SiO₅
Aluminium silicate formed by regional metamorphism at moderately high pressure. Unusual in having two different hardnesses: 5.5 along the crystal length and 7 across it. Used as an indicator mineral to estimate the pressure of metamorphism.
Identity
- Formula
- Al₂SiO₅
- Chemical class
- Silicate
- Also known as
- Cyanite, Disthene
Crystallography
- Crystal system
- Triclinic
- Habits
- Bladed, Tabular
- Fracture
- Splintery
Physical properties
- Mohs hardness
- 5.5
- Density
- 3.67 g/cm³
- Luster
- Vitreous, Pearly
- Colors
- blue, pale blue, white, gray, green, black
- Streak
- white
- Transparency
- Transparent, Translucent
Geology
- Origins
- Metamorphic
- Host rocks
- Granite, Schist and gneiss
- Associated minerals
- Quartz, Staurolite, Garnet, Mica
- Found in
- Hydrothermal vein (lode), Pegmatite deposit
- Geography
- Brazil (Minas Gerais), USA, Kenya, Austria (Tyrol), Switzerland (Ticino), Russia (Ural Mountains)
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.
- Kyanite. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Kyanite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
Browse the Crystal Encyclopedia — MGS Toolbox