mineral

Likely raw blue kyanite specimens

Kyanite, Al₂SiO₅

AI-generated identification · may be incorrect

Typically blue, bladed crystals with vitreous to pearly luster and strong directional hardness: about 4.5 parallel to blades and 6.5–7 across them; perfect cleavage and triclinic structure. The image appears to show blue fragments on a mineral-rich slab, though exact identification is uncertain from the photograph.

Hardness: about 4

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Kyanite forms mainly in aluminum-rich metamorphic rocks, especially schist and gneiss, under medium- to high-pressure conditions during regional metamorphism. It commonly crystallized during Paleozoic to younger mountain-building events.

Uses & applications

Used as a refractory and ceramic raw material because it expands predictably when heated; attractive blue crystals are collected and occasionally used as cabochons or ornamental material.

Geological facts

Kyanite, andalusite, and sillimanite share the same composition but form under different pressure-temperature conditions. Its unusually directional hardness is a useful diagnostic feature.

Field identification & locations

Look for elongated blue blades, prominent cleavage, and hardness changing with direction; common sources include Nepal, Brazil, Switzerland, India, and the United States. A streak, hardness, and locality test would be needed to distinguish it from blue schorl, dumortierite, or corundum.