mineral
Kyanite
Al2SiO5
Hardness: 4.5-5 along length, 6.5-7 across width (Mohs), Color: Blue, white, gray, green, Luster: Vitreous to pearly, Crystal structure: Triclinic, Cleavage: Perfect in two directions
- Hardness
- 4
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Physical properties
Hardness: 4.5-5 along length, 6.5-7 across width (Mohs), Color: Blue, white, gray, green, Luster: Vitreous to pearly, Crystal structure: Triclinic, Cleavage: Perfect in two directions
Formation & geological history
Forms during regional metamorphism of clay-rich sediments, primarily in schists and gneisses
Uses & applications
Used in the manufacture of refractory materials, ceramics, and occasionally as a gemstone or for collecting
Geological facts
Kyanite is strongly anisotropic, meaning highly variable hardness depending on the direction it is scratched.
Field identification & locations
Identified by its bladed crystals, blue color, and distinct hardness variations. Found in areas like Brazil, USA, Switzerland, and India.
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