triclinic Nesosilicates
Kyanite
Al2SiO5
Quick Facts
Hardness
4.0
Specific Gravity
3.53
Refractive Index
1.716
Optical Character
Biaxial -
Crystal Structure
#! Species: Kyanite
#! System: Triclinic (-1)
#! Habit: Bladed with directional colour zoning
triclinic[-1]:{100}@1.0[colour_zone:directional] + {010}@0.4 + {001}@1.5 + {110}@0.6
triclinic
-1
{100} {010} {001} {110}
Physical Properties
Crystal Systemtriclinic
Hardness (Mohs)4.0
Specific Gravity3.53
CleavagePerfect {100}, good {010}
FractureSplintery
LustreVitreous to pearly
Optical Properties
Refractive Index1.716
Birefringence0.012-0.017
Optical CharacterBiaxial -
Dispersion0.02
Pleochroismstrong: Colourless to pale blue / Deep blue (Strong pleochroism visible in different crystallographic directions)
Colours
Blue (classic)Blue with colorless zonesGreenOrange (rare)ColorlessGray
Localities
Nepal (gem quality)BrazilKenya (green)SwitzerlandIndiaUSA (North Carolina)
Crystal Forms
pinacoidbladed crystals
Diagnostic Features
Directional hardness (4-7); blue bladed crystals; triclinic; perfect cleavage {100}
Notes
Diagnostic variable hardness; often contains color zoning; parting on {001}; good toughness despite cleavage
Interactive Preview
Open this crystal in the CDL Playground to rotate, export, and explore in 3D.
Open in Playground #! Species: Kyanite
#! System: Triclinic (-1)
#! Habit: Bladed with directional colour zoning
triclinic[-1]:{100}@1.0[colour_zone:directional] + {010}@0.4 + {001}@1.5 + {110}@0.6
Related Minerals
Other minerals in the triclinic system
