mineral

Blue Kyanite

Kyanite (Al2SiO5)

Hardness: 4.5 to 5.0 parallel to the length and 6.5 to 7.0 across the crystals (anisotropy). Color: Blue with white streaks. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect one-directional. Specific gravity: 3.53 to 3.67.

Hardness: 4
Color: Blue with white streaks
Luster: Vitreous to pearly

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed during the regional metamorphism of clay-rich sedimentary rocks under high pressure. Commonly found in metamorphic rocks like schists, gneisses, and occasionally in pegmatites. It serves as an index mineral for high-pressure environments.

Uses & applications

Used in the manufacture of heat-resistant ceramics (spark plugs, kiln linings, foundry molds), abrasives, and as a minor gemstone for jewelry. It is also a very popular specimen for mineral collectors and metaphysical practitioners.

Geological facts

Kyanite is unusual because it has two different hardness ratings depending on the direction of the scratch test. Its name is derived from the Greek word 'kyanos', meaning deep blue. It is a polymorph with andalusite and sillimanite.

Field identification & locations

Identify in the field by its distinct blue bladed crystal habit and variable hardness. Major deposits are found in Brazil, USA (North Carolina), Nepal, and Switzerland. Collectors look for long, unbroken bladed crystals with deep saturation.