mineral
Blue Kyanite
Kyanite (Al2SiO5)
Hardness: 4.5 to 7 (anisotropic); Color: Blue, streaks of white/grey; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect in one direction.
- Hardness
- 4
- Color
- Blue, streaks of white/grey
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 4.5 to 7 (anisotropic); Color: Blue, streaks of white/grey; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect in one direction.
Formation & geological history
Formed during high-pressure regional metamorphism of clay-rich sedimentary rocks. Common in metamorphic facies such as blueschist or eclogite.
Uses & applications
Used in the manufacturing of heat-resistant ceramics, spark plugs, and refractory linings. High-quality specimens are used in jewelry and as popular metaphysical crystals.
Geological facts
Kyanite is one of the few minerals that exhibits a significant variation in hardness depending on the direction it is scratched; it is 4.5 parallel to the long axis and 7 perpendicular to it.
Field identification & locations
Identify in the field by its bladed crystal habit, distinct blue color, and varying hardness. Commonly found in metamorphic belts in Brazil, USA, and Switzerland.
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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
Granite
Granite (Phaneritic intrusive igneous rock)
igneous