Kyanite
Kyanite · Mineral Specimen and Semi-Precious Gemstone
Crystal System
Triclinic, typically forming elongate, tabular, blade-like crystals
Mineral Group
Silicates, specifically Nesosilicates
Chemical Formula
Al2SiO5
Formation Process
Metamorphic, formed primarily through regional metamorphism of clay-rich sediments and pelitic rocks under high pressures and varying temperatures
About This Crystal
The specimen is a pale bluish-green to greyish-blue bladed crystal fragment showing characteristic striated crystal faces and distinct cleavage steps along its length, with translucent to semi-transparent areas and a vitreous to pearly luster
Physical Characteristics
Color ranges from light blue, green, grey, to nearly colorless with a white streak; perfect cleavage in one direction parallel to the blade; uneven to splintery fracture; specific gravity around 3.53 to 3.67; notable for its highly anisotropic hardness
Optical Properties
Biaxial negative with strong optical anisotropy; refractive indices are nalpha=1.710-1.729, nbeta=1.715-1.734, ngamma=1.720-1.740; exhibits weak to moderate pleochroism in colored varieties
Hardness & Durability
Origin Region
Notable sources include Brazil, Switzerland, Russia, Nepal, USA (North Carolina), and Kenya, typically in aluminum-rich metamorphic rocks
Hardness & Durability
Mohs hardness is famously variable: 4.5 to 5.5 parallel to the length of the blade and 6.5 to 7.0 across the width; exhibits perfect cleavage making it brittle and challenging to use safely in everyday jewelry without protective settings
Care & Maintenance
Clean gently with warm soapy water and a soft brush; avoid harsh chemical cleaners, ultrasonic cleaners, and steam cleaning; store separately from harder minerals to prevent scratching, and protect from hard impacts due to perfect cleavage
Rarity & Value
Common to uncommon as mineral specimens, with fine gem-grade transparent material being rare and more valuable; value depends on color saturation, clarity, and crystal size, generally ranging from affordable to moderately priced for collector specimens
Special Characteristics
Notable for its extreme directional hardness (anisotropy), which is a key diagnostic property used to distinguish it from similar minerals, along with its characteristic blade habit and strong bladed cleavage
Lore & History
Historically named from the Greek word 'kyanos' meaning dark blue; in modern crystal healing traditions, it is often associated with the throat and third-eye chakras, believed to promote alignment, calm energy, and clear communication, though these are traditional beliefs without scientific backing