mineral

Likely blue kyanite

Kyanite, Al₂SiO₅

AI-generated identification · may be incorrect

Small, rough blue-gray blade with a pearly to vitreous luster and prominent lengthwise striations. Kyanite has triclinic crystals, perfect cleavage, and unusual directional hardness: about Mohs 4.5–5 parallel to the blades and 6.5–7 across them; identification from the photo is tentative.

Hardness: about Mohs 4

Identified September 27, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly during regional metamorphism of aluminum-rich sedimentary rocks, commonly in schist and gneiss. Its age depends on the host rock and may range from millions to billions of years.

Uses & applications

Used in high-temperature ceramics and refractory products; attractive blue material is cut for jewelry, though this specimen appears small and rough.

Geological facts

Kyanite, andalusite, and sillimanite share the composition Al₂SiO₅ but form under different pressure-temperature conditions.

Field identification & locations

Look for flattened, striated blue blades and strongly differing hardness by direction; common sources include Brazil, Nepal, India, and the United States. A small specimen like this typically sells for about $2–$15 USD.