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Name Origin | Kyanite color stone gets its name from the Greek kyanos, meaning blue |
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Chemical Formula | Al2SiO5 |
Color | Blue, blue-green, green; also white, gray, yellow, pink, nearly black. Color zoned in individual crystals. |
Hardness | 4 - 7.5 on Mohs Scale |
Crystal System | Triclinic. Crystals bladed, flattened and elongated; fibrous, massive |
Cleavage | Perfect 1 directions |
Specific Gravity (SG) | 3.53 - 3.68; gems usually upper end of range |
Pleochroism | Pronounced: violet-blue/colorless/cobalt-blue Also pleochroic in all shades of yellow-green and green |
Luster | Vitreous; pearly on cleavage |
Stone sizes |
Gems have been cut up to about 20 carats; they are seldom completely clean over 5 carats, however. |
Spectral | one line observed in deep red at 7100 and 2 lines in deep blue, with dark edge at about 6000 |
Note: Kyanite is typically blue in color. The blue is the most intense in the center of crystal blades and becomes paler toward the edges, sometimes changing to white or colorless. Kyanite is very rare as a faceted gem, especially if free from inclusions and flaws. The material is extremely difficult to cut because of its perfect cleavage and the extreme variability in hardness in different directions in the same crystal. A few catseye kyanites are know to exist.
Photo Credit:
"Kyanite crystals" by User:Aelwyn - Self made picture. Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Kyanite_crystals.jpg#/media/File:Kyanite_crystals.jpg
www.shutterstone.com
"Kyanite crystals" by User:Aelwyn - Self made picture. Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Kyanite_crystals.jpg#/media/File:Kyanite_crystals.jpg
www.shutterstone.com