mineral

Blue kyanite

Kyanite (Al₂SiO₅)

AI-generated identification · may be incorrect

Usually blue, bladed, and strongly fibrous with pearly-to-vitreous luster; Mohs hardness is 4.5–5 parallel to blades and 6.5–7 across them. It has distinct cleavage and commonly forms flattened, striated blades; specific gravity is about 3.5–3.7.

Identified September 8, 2026More mineral →

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Physical properties

Formation & geological history

A metamorphic aluminosilicate formed mainly in medium- to high-pressure schists and gneisses during regional metamorphism, commonly associated with quartz and mica. Individual crystals may be hundreds of millions to billions of years old depending on the host rock.

Uses & applications

Used as a refractory ceramic material because it expands predictably when heated; gem-quality transparent blue material is cut into cabochons or occasionally faceted. Small natural specimens are common collector pieces.

Geological facts

Its unusual hardness variation by direction is diagnostic and reflects its anisotropic crystal structure. The blue color generally comes from trace iron and titanium.

Field identification & locations

Identify it by blue, blade-like crystals, strong lengthwise striations, pearly cleavage surfaces, and directional hardness; common sources include Nepal, Brazil, India, Kenya, Switzerland, and the United States. Value is typically $5–$30 for a small rough specimen, or $30–$150+ for attractive cabinet specimens or gem-quality material.