mineral
Blue Kyanite
Kyanite (Al2SiO5)
Hardness: 4.5-5 (along axes) and 6.5-7 (across axes). Color: Blue, gray, white. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect in one direction. Specific gravity: 3.53-3.67.
- Hardness
- 4
- Color
- Blue, gray, white
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 4.5-5 (along axes) and 6.5-7 (across axes). Color: Blue, gray, white. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect in one direction. Specific gravity: 3.53-3.67.
Formation & geological history
Formed during the regional metamorphism of clay-rich sedimentary rocks (pelites) under high pressure and low to moderate temperatures. It is often found in schists and gneisses.
Uses & applications
Used in the manufacturing of refractory products like bricks and mortars for furnaces, spark plugs, ceramic fixtures, and occasionally as a gemstone for jewelry or collecting.
Geological facts
Kyanite is highly anisotropic, meaning its hardness varies significantly depending on the crystallographic direction. It was once called disthene, meaning 'two strengths'.
Field identification & locations
Identify in the field by its bladed crystal habit, distinct blue color, and varying hardness. Commonly found in Brazil, Switzerland, Russia, and the Appalachian Mountains of the USA.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock