mineral
Green Kyanite
Kyanite (Al2SiO5)
Hardness: 4.5–5 parallel to the axis and 6.5–7 perpendicular to the axis (highly anisotropic). Color: Pale to sea green. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect in one direction.
- Hardness
- 4
- Color
- Pale to sea green
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 4.5–5 parallel to the axis and 6.5–7 perpendicular to the axis (highly anisotropic). Color: Pale to sea green. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect in one direction.
Formation & geological history
Formed through high-pressure regional metamorphism of clay-rich sedimentary rocks. Usually found in aluminous metamorphic rocks like schists and gneisses.
Uses & applications
Used in the manufacture of refractory materials (bricks, mortars) for high-heat furnaces, glassmaking, and in spark plugs. It is also a popular collector’s mineral and semi-precious gemstone.
Geological facts
Kyanite is unique because its hardness varies significantly based on the direction of the crystal. While blue is the most common color, green kyanite is rarer and gets its color from trace amounts of chromium or iron.
Field identification & locations
Identify in the field by its distinct bladed crystal habit and its varying hardness when scratched in different directions. Commonly found in Brazil, India, and North Carolina, USA.
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Banded Gneiss (River Rock/Pebble)
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Green Apatite on Albite
Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]
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Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
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