mineral

Kyanite

Kyanite, Al₂SiO₅

AI-generated identification · may be incorrect

Blue-gray, bladed mineral with pearly to vitreous luster and prominent lengthwise striations. Mohs hardness is strongly directional: about 4.5–5 parallel to blades and 6.5–7 across them; typically has excellent cleavage and a triclinic crystal structure.

Identified September 4, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in aluminum-rich, high-pressure metamorphic rocks such as schist and gneiss, commonly during regional metamorphism of clay-rich sediments. It is generally associated with Paleozoic to younger metamorphic terrains, though the mineral itself can be much older.

Uses & applications

Used as a refractory and ceramic raw material because it converts to mullite and expands predictably when heated; attractive blue crystals are sold as collector specimens and occasionally cut as gemstones.

Geological facts

The specimen’s elongated, blue-gray, striated blade strongly matches kyanite, though laboratory testing would distinguish it from sillimanite or fibrous blue minerals.

Field identification & locations

Common localities include Nepal, India, Brazil, Kenya, Switzerland, and the southeastern United States. Identify it by bladed habit, strong directional hardness, cleavage, and association with mica schist; avoid acid testing.