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Chemical Composition : Al2SiO5 Aluminum Silicate
Hardness : 5.5 – 7.0
Specific Gravity (Density) : 3.53 – 3.65 (g/cm3)
Refractive Index : 1.712 – 1.734 Biaxial ( – )
Kyanite is a beautiful gem that varies in color from pale blue to very dark blue to green and rarely yellow or pink. Crystals from Brazil may have both blue and green zoned lengthwise. A recent find in Tanzania has produced beautiful orange crystals. The blue variety is most common and may have a beautiful sapphire-blue color. Kyanite is somewhat rare as a faceted gem due to its perfect clevage and extreme variability in hardness in different directions. Kyanite is trimorphous with Andalusite and Sillimanite meaning all three share the same basic chemical formula but have different crystal structures. Notable sources of gem material are Minas Gerais, Brazil, Nepal, Loliondo, Tanzania and Tibet.
Distribution: Widely distributed, even in good crystals. From Mt. Greiner, Zillertal, Tirol, Austria. At Alpe Sponda, Pizzo Forno, and at Alpe Campolungo, Tessin, Switzerland. In the Pfitschtal, Trentino-Alto Adige, Italy. From Röros, Norway. Around Yekaterinburg (Sverdlovsk), Ural Mountains, Russia. At Elovyi, Klavoloke, Karelia. From Sultan Hamud, Machakos district, Kenya. Large crystals from a number of localities in Minas Gerais, Brazil, as at Barro Prêto, São José do Jacuri. Beautiful orange crystals from Nani, Loliondo, Arusha Region, Tanzania. In the USA, at Lyme, Grafton County, New Hampshire; at Judd’s Bridge, Litchfield County, Connecticut; at Darby, Delaware County, Pennsylvania; from near Bakersville, Mitchell County, and near Burnsville, Yancy County, North Carolina; on Willis Mountain, Buckingham County, Virginia.