mineral

Kyanite (Blue and Green varieties)

Kyanite (Al₂SiO₅)

Hardness: highly anisotropic (4.5 to 7.0 Mohs); Color: blue, teal, or pale green; Luster: vitreous to pearly; Crystal structure: triclinic; Cleavage: perfect in one direction; Specific gravity: 3.53–3.67.

Hardness: highly anisotropic (4
Color: blue, teal, or pale green
Luster: vitreous to pearly

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed through high-pressure regional metamorphism of clay-rich sedimentary rocks (pelites). Commonly found in schist and gneiss; geological age ranges from Precambrian to Cenozoic depending on the tectonic locale.

Uses & applications

Used industrially for refractory materials (high-heat porcelain, spark plugs, brick linings) and as a semi-precious gemstone for jewelry and metaphysical collections.

Geological facts

Kyanite is unusual because its hardness varies significantly depending on which direction you scratch it (anisotropy). It is an aluminosilicate polymorph, sharing the same chemistry as Andalusite and Sillimanite but forming at different pressures.

Field identification & locations

Identify by its bladed/columnar crystal habit, pearly luster, and varying hardness. Common locations include Brazil, Switzerland, Russia, and the United States (North Carolina). Rough specimens appear as splintery, elongated blades.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock

Granite

Granite (Phaneritic intrusive igneous rock)

igneous