Blue Kyanite
Kyanite (variety of Aluminosilicate) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Triclinic; commonly occurs as long, bladed, flattened crystals or columnar aggregates.
Mineral Group
Silicates (Nesosilicates)
Chemical Formula
Al2SiO5 (Aluminum Silicate)
Formation Process
Metamorphic; forms during the regional metamorphism of clay-rich sedimentary rocks under high pressure and low to medium temperatures.
About This Crystal
Elongated, bladed habit with a characteristic deep blue to indigo color, often with white or translucent streaks. Displays a vitreous to pearly luster and is translucent to transparent in thin sections.
Physical Characteristics
Color: Blue to blue-grey; Streak: White; Cleavage: Perfect in one direction, good in another; Fracture: Splintery; Specific Gravity: 3.53–3.67; Fluorescence: Occasionally weak red under UV.
Optical Properties
Biaxial negative; Refractive Index: 1.712–1.734; Birefringence: 0.012–0.020; Pleochroism: Distinct (colorless to light blue to dark blue).
Hardness & Durability
Origin Region
Brazil (Minas Gerais), Nepal, Switzerland, India, and the United States (North Carolina/Virginia).
Hardness & Durability
Highly anisotropic hardness: 4.5–5.0 parallel to the long axis and 6.5–7.0 perpendicular to the long axis. Brittle tenacity.
Care & Maintenance
Avoid ultrasonic and steam cleaners due to splintery fracture. Use warm soapy water and a soft cloth. Store separately from harder stones like sapphire to prevent scratching.
Rarity & Value
Relatively common in mineral form but rare in gem quality. Value increases with color depth, clarity, and size. Frequently untreated, though occasionally dyed.
Special Characteristics
Notable for its extreme anisotropy of hardness (hardness varies significantly by direction) and its distinct bladed crystal habit.
Lore & History
Historically used as a 'compass' to guide travelers. In modern metaphysical beliefs, it is associated with the throat chakra, intended for communication and alignment without holding negative energy.