metamorphic
Blue Kyanite
Kyanite (Al2SiO5)
Hardness: Variable (4.5-5.0 parallel to axes, 6.5-7.0 perpendicular), Color: Blue to indigo, Luster: Vitreous to pearly, Crystal Structure: Triclinic (bladed), Cleavage: Perfect in one direction.
- Hardness
- Variable (4
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Physical properties
Hardness: Variable (4.5-5.0 parallel to axes, 6.5-7.0 perpendicular), Color: Blue to indigo, Luster: Vitreous to pearly, Crystal Structure: Triclinic (bladed), Cleavage: Perfect in one direction.
Formation & geological history
Formed during regional metamorphism of clay-rich sedimentary rocks at high pressure. Common in schists and gneisses.
Uses & applications
Used in the manufacture of high-temperature ceramics, kiln linings, abrasives, and as a semi-precious gemstone for jewelry and metaphysical collections.
Geological facts
Kyanite is highly anisotropic, meaning it has a different hardness depending on the direction it is scratched. It is one of the three polymorphs of Al2SiO5 along with andalusite and sillimanite.
Field identification & locations
Identifiable by its bladed crystal habit and distinct blue color. Commonly found in Brazil, Nepal, and the United States (Appalachian Mountains).
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