mineral

Blue Kyanite

Kyanite (Al2SiO5)

Hardness: 4.5 parallel to the long axis and 6.5-7.0 perpendicular; Color: Blue-grey to sky-blue; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect in one direction.

Hardness: 4
Color: Blue-grey to sky-blue
Luster: Vitreous to pearly

Identified July 20, 2026More mineral →

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Physical properties

Hardness: 4.5 parallel to the long axis and 6.5-7.0 perpendicular; Color: Blue-grey to sky-blue; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect in one direction.

Formation & geological history

Forms in regional metamorphic environments where aluminum-rich sedimentary rocks (like shale) undergo high-pressure, low-temperature metamorphism.

Uses & applications

Used in the manufacture of heat-resistant ceramics, spark plugs, abrasive wheels, and as a gemstone for jewelry or metaphysical collecting.

Geological facts

Kyanite is strongly anisotropic, meaning it has two different hardness ratings depending on the direction it is scratched. It is one of the three polymorphs of Al2SiO5 alongside andalusite and sillimanite.

Field identification & locations

Identified by its distinctive bladed crystal habit and blue color. Common in metamorphic belts such as the Appalachian Mountains in the US, Brazil, and India.