mineral

Blue Kyanite

Kyanite (Al2SiO5)

Hardness: Variable (4.5 parallel to axes, 7 perpendicular); Color: Blue, white, gray; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect; Specific Gravity: 3.53–3.67.

Hardness: Variable (4
Color: Blue, white, gray
Luster: Vitreous to pearly

Identified May 24, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: Variable (4.5 parallel to axes, 7 perpendicular); Color: Blue, white, gray; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect; Specific Gravity: 3.53–3.67.

Formation & geological history

Forms during the regional metamorphism of clay-rich sedimentary rocks (pelites) at high pressures and relatively low temperatures. Common in schists and gneisses worldwide.

Uses & applications

Used in the manufacture of heat-resistant ceramics, spark plugs, and refacting bricks for furnaces. Also popular as a semi-precious gemstone for jewelry and metaphysical collections.

Geological facts

Kyanite is unique because it is anisotropic, meaning its hardness varies significantly depending on the direction of the scratch. It is used as an index mineral to determine pressure/temperature paths of rocks.

Field identification & locations

Identified by its bladed crystal habit, distinct blue color, and differential hardness. Commonly found in metamorphic belts like the Appalachians or the Himalayas.