metamorphic
Kyanite in Quartz
Kyanite (Al2SiO5) with Quartz (SiO2) matrix
Hardness: 4.5 to 7 (anisotropic: 4.5 parallel to length, 7 perpendicular); Color: Blue blades with clear/white matrix; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect in one direction.
- Hardness
- 4
- Color
- Blue blades with clear/white matrix
- Luster
- Vitreous to pearly
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 4.5 to 7 (anisotropic: 4.5 parallel to length, 7 perpendicular); Color: Blue blades with clear/white matrix; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect in one direction.
Formation & geological history
Formed through the regional metamorphism of clay-rich sedimentary rocks under high pressure and relatively low temperatures. Commonly found in schists and gneisses.
Uses & applications
Used in the manufacture of refractory products (high-heat porcelain/ceramics), spark plugs, and as a semi-precious gemstone in jewelry or collector clusters.
Geological facts
Kyanite is unusual because its hardness varies significantly depending on the direction of the scratch test. It is a blue polymorph of aluminosilicate, sharing the same chemistry as sillimanite and andalusite.
Field identification & locations
Identify by the elongated, bladed crystal habit and distinct blue color. Found in high-grade metamorphic terrains like the Appalachian Mountains, Brazil, and India.
More like this
