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A natural bluish-green aluminum silicate mineral. Kyanite has transparent, triclinic long-bladed crystals that appear fibrous or blade-like. It is a common mineral; most of the world's production is from mines in India, Kenya, Ural Mountains, Austria, Italy (Trentino), Switzerland, France and the United States (Massachusetts, Connecticut, North Carolina, Georgia, Virginia). Some clear blue kyanite crystals have been used as gemstones. Kyanite powder, obtained from Florida beach sands, is used for glassmaking and ceramics. Since kyanite is refractory, it is commonly used for lining furnaces. A synthetic kyanite, called Cerox ceramic, is also used for furnace parts.


Synonyms and Related Terms

yanite; disthene; rhoetizite; Cerox ceramic; aluminum silicate; Kyanit (Deut.); Cyanit (Deut.); cianite (It., Port.); kyaniet (Ned.)

Other Properties

Triclinic system. Luster = vitreous to pearly. Fracture = splintery. Streak = colorless.

Cleavage is perfect lengthwise and good in another direction.

Mohs hardness is 4-5 lengthwise and 6-7 crosswise.

Composition Al2O3.SiO3
Mohs Hardness 4 - 7 (directional)
Melting Point 3290
Density 3.56-3.67
Refractive Index 1.71; 1.72; 1.73

Additional Information

Mineralogy Database: Kyanite

Additional Images

Sources Checked for Data in Record

  • Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 434
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997