Kyanite
Kyanite (IMA approved) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; typically forms in bladed, elongated crystals that are often flattened and aggregated. Twinning is common on {100}.
Mineral Group
Silicates; Nesosilicate (within the Al2SiO5 polymorph group)
Chemical Formula
Al2SiO5 (Aluminum Silicate)
Formation Process
Metamorphic; typically forms in high-pressure, regional metamorphic environments including schists and gneisses.
About This Crystal
Elongated, bladed habit with a visible pearly to vitreous luster. Features a signature blue color with variable zoning (white or gray streaks). It is translucent to transparent with a distinct fibrous texture.
Physical Characteristics
Blue body color with a white streak; perfect cleavage on {100}; uneven fracture; specific gravity 3.53-3.67; typically non-fluorescent; noted for extreme hardness anisotropy.
Optical Properties
Biaxial negative; refractive index 1.712-1.734; high birefringence (0.017-0.020); strong pleochroism (colorless to violet-blue to cobalt blue).
Hardness & Durability
Origin Region
Brazil, Nepal, Tibet, Switzerland, and the USA (North Carolina). Commonly found in aluminous metamorphic rocks.
Hardness & Durability
Highly anisotropic: 4.5 to 5.0 parallel to the long axis, 6.5 to 7.0 perpendicular to it. Brittle tenacity; poor wearability in rings due to easy cleavage.
Care & Maintenance
Clean with warm soapy water only; avoid ultrasonic cleaners and steam cleaning. Store separately to avoid scratching softer materials or being scratched by harder ones.
Rarity & Value
Common as a mineral, but gem-quality transparent material is uncommon. Value is based on color saturation and clarity. Rarely treated, though some may be oiled.
Special Characteristics
Anisotropy of hardness (the 'Disthene' property); occasionally shows chatoyancy; serves as a high-pressure metamorphic index mineral.
Lore & History
Historically used as a compass by travelers who believed it could hang from a hair and follow the Earth's magnetic force. Traditionally associated with the Throat Chakra and thought to promote communication.