Blue Kyanite
Kyanite (variety of Nesosilicate) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; typically forms in long, flattened, bladed crystals that are often aggregated.
Mineral Group
Silicates; Nesosilicate (Aluminosilicate polymorph group)
Chemical Formula
Al2SiO5 (Aluminum Silicate)
Formation Process
Metamorphic; forms under high-pressure regional metamorphism of clay-rich sedimentary rocks (pelites). It is an indicator mineral of high-pressure environments.
About This Crystal
A deep blue, bladed specimen with a pearly to vitreous luster. It exhibits strong color zoning with darker blue centers and lighter edges. The texture is distinctly fibrous and splintery.
Physical Characteristics
Color: Blue with white or grey streaks. Streak: White. Cleavage: Perfect in one direction, good in another. Specific Gravity: 3.53–3.67. Fluorescence: Often weak red under long-wave UV.
Optical Properties
Biaxial negative. Refractive Index: 1.712–1.734. Birefringence: 0.012–0.017. Strong pleochroism (colorless to violet-blue to cobalt-blue).
Hardness & Durability
Origin Region
Brazil, Nepal, Tibet, Switzerland (St. Gotthard), and USA (North Carolina). Typically found in metamorphic rocks.
Hardness & Durability
Notable variable hardness (anisotropy): 4.5 to 5 parallel to the long axis, and 6.5 to 7 perpendicular to the axis. Low toughness due to cleavage; fragile.
Care & Maintenance
Avoid ultrasonic cleaners and steam. Clean with warm, soapy water and a soft cloth. Store separately to prevent the blades from splintering or scratching softer stones.
Rarity & Value
Common as a mineral; gem-quality transparent material is uncommon. Value is based on color depth (deep 'sapphire' blue is prized) and transparency. Usually untreated.
Special Characteristics
Anisotropy (significant hardness variation based on direction), bladed growth habit, and distinct pearly luster on cleavage faces.
Lore & History
Historically used as a compass by travelers who believed it could follow Earth's magnetic force. In modern lore, it is associated with the Throat Chakra, communication, and self-expression.