Kyanite
Description
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.)
Risks
- Kyanite Mining: SDS
Physical and Chemical Properties
- Triclinic system with columnar, fibrous or bladed crystals
- Luster = vitreous to pearly
- Fracture = splintery
- Streak = white
- Cleavage is perfect lengthwise and good in another direction
- Mohs hardness is 4-5 lengthwise and 6-7 crosswise.
- Fluorescence = weak red under LW
- Pleochroism = trichroic; moderate intensity; usually colorless, dark blue and violet
| Composition | Al2O3.SiO3 |
|---|---|
| Mohs Hardness | 4 - 7 (directional) |
| Melting Point | 3290 C |
| Density | 3.56-3.67 g/ml |
| Refractive Index | 1.71; 1.72; 1.73 |
| Birefringence | 0.012 - 0.017 |
Resources and Citations
- Gem Identification Lab Manual, Gemological Institute of America, 2016.
- Mineralogy Database: Kyanite
- 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
- Encyclopedia Britannica, http://www.britannica.com Comment: "kyanite" [Accessed December 4, 2001].
- Wikipedia: http://en.wikipedia.org/wiki/Kyanite (Accessed Sept. 7, 2005 and Dec 2022)
- 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