Blue Kyanite
Kyanite · Mineral Specimen and Semi-Precious Gemstone
Crystal System
Triclinic; typically forms elongated, blade-like, tabular crystals with striated faces.
Mineral Group
Silicates (Nesosilicate subgroup)
Chemical Formula
Al2SiO5
Formation Process
Metamorphic, primarily formed via regional metamorphism of argillaceous (clay-rich) sediments under high pressures and moderate temperatures in pelitic schists and gneisses.
About This Crystal
The specimen displays striking blue blade-like crystal clusters with pronounced linear striations along the length of the blades. It exhibits varying shades of light to medium blue, intermixed with white matrix and grayish-white associated minerals. The luster ranges from vitreous to pearly on cleavage planes, and the transparency is translucent to transparent in thinner blade sections.
Physical Characteristics
Color varies from light blue to deep indigo, sometimes with white patches. Streak is white. Perfect cleavage in one direction parallel to the blade length, and a distinct second cleavage. Fracture is splintery. Specific gravity is approximately 3.53 to 3.67. Tenacity is brittle except along the cleavage planes where it can be slightly flexible in thin laminations.
Optical Properties
Biaxial negative with two refractive indices ranging generally between 1.710 and 1.734. Shows strong pleochroism, displaying colorless, dark blue, and light blue from different angles. Birefringence is strong (around 0.012 to 0.016).
Hardness & Durability
Origin Region
Notable sources include Brazil, Switzerland, Austria, Kenya, Myanmar, and the USA (North Carolina). Forms in aluminum-rich metamorphic environments.
Hardness & Durability
Notable for extreme directional hardness: Mohs hardness is 4 to 4.5 parallel to the length of the blades, but 6 to 7 across the width. Because of this perfect cleavage and variable hardness, it has poor durability and is rarely used in rings or bracelets without protective settings.
Care & Maintenance
Clean gently with warm, soapy water and a soft brush. Avoid ultrasonic and steam cleaners, harsh chemicals, and prolonged exposure to acids. Store separately from harder minerals to prevent scratching, and handle with care due to brittle cleavage.
Rarity & Value
Common to Uncommon, depending on the quality and size of blade clusters. Well-formed blade clusters on matrix like this mounted specimen are popular among mineral collectors. Prices vary widely based on size, color saturation, and aesthetic arrangement.
Special Characteristics
Anisotropic hardness is the most famous physical anomaly of kyanite, meaning it can be easily scratched in one direction while resisting scratching in another direction on the same crystal face. It also forms blade aggregates and fan-like sprays.
Lore & History
Historically used to make primitive compasses due to its directional hardness and magnetic-like alignment associations in early folklore. In modern crystal healing, Kyanite is associated with the throat chakra, believed to encourage communication, tranquility, truth, and alignment of all energy centers without retaining negative energy.