Blue aluminum silicate polymorph with the unusual property of variable hardness: 4.5 along the crystal length but 7 across it. Color: Blue, white, gray, green. Luster: Vitreous to pearly. Streak: White. Cleavage: Perfect in one direction. Hardness: 4.5-7 variable. Transparency: Transparent to translucent. Crystal system: Triclinic. Chemical formula: Al₂SiO₅. Specific gravity: 3.53-3.67. Formation: Forms during medium to high pressure regional metamorphism of aluminum-rich sedimentary rocks. Common geological settings: Brazil, Nepal, Kenya, USA; found in kyanite-bearing schists and gneisses. Common look-alikes and related entries: Sillimanite, Andalusite, Sapphire.
Blue minerals — Place this specimen in a broader field-identification workflow.
Sources, scope & corrections
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
Editorial owner
GeoMiner
Last updated
2026-03-30T14:36:54.390292+00:00
Review status
Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Blue aluminum silicate polymorph with the unusual property of variable hardness: 4.5 along the crystal length but 7 across it.
How can you identify Kyanite?
Compare several properties rather than relying on colour alone. This entry records colour: Blue, white, gray, green; lustre: Vitreous to pearly; streak: White; Mohs hardness: 4.5-7 variable; cleavage: Perfect in one direction; crystal system: Triclinic; transparency: Transparent to translucent. Confirm an important identification with additional field tests or qualified laboratory work.
How does Kyanite form?
Forms during medium to high pressure regional metamorphism of aluminum-rich sedimentary rocks.
Where is Kyanite commonly found?
Brazil, Nepal, Kenya, USA; found in kyanite-bearing schists and gneisses.
What is Kyanite commonly confused with?
Kyanite may be confused with Sillimanite, Andalusite, Sapphire. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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