Difference between revisions of "Kyanite" - New World Encyclopedia
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| − | '''Kyanite''', whose name derives from the Greek word ''kyanos'', meaning blue, is a typically blue [[silicate]] [[mineral]], commonly found in [[aluminium]]-rich metamorphic [[pegmatite]]s and | + | '''Kyanite''', whose name derives from the Greek word ''kyanos'', meaning blue, is a typically blue [[silicate]] [[mineral]], commonly found in [[aluminium]]-rich metamorphic [[pegmatite]]s and [[sedimentary rock]]s. Kyanite is a diagnostic mineral of the [[Blueschist Facies]] of [[metamorphic]] rocks. |
| − | + | == Characteristics == | |
| − | + | Kyanite is a member of the aluminosilicate group of [[silicate]] minerals. It has two [[polymorphism (materials science)|polymorphs]]: [[andalusite]] and [[sillimanite]]. Kyanite and its polymorphs have the same chemical formula, Al<sub>2</sub>SiO<sub>5</sub>, but they differ in crystalline structure. | |
| − | Kyanite | + | |
| + | Kyanite is strongly [[anisotropy|anisotropic]], in that its [[Mohs scale of mineral hardness|hardness]] varies depending on its crystallographic direction. While this is a feature of almost all minerals, in kyanite this anisotropism can be considered an identifying characteristic. | ||
| + | |||
| + | === Identifying traits === | ||
| + | |||
| + | Kyanite's elongated, columnar crystals are usually a good first indication of the mineral, as well as its color (when the specimen is blue). Associated minerals are useful as well, especially the presence of the polymorphs or staurolite, which occur frequently with kyanite. However, the most useful characteristic in identifying kyanite is its anisotropism. If one suspects a specimen to be kyanite, verifying that it has two distinctly different hardnesses on perpendicular axes is a key to identification. | ||
==Associated minerals== | ==Associated minerals== | ||
| − | Kyanite is usually found in association with its polymorphs | + | |
| + | Kyanite is usually found in association with its polymorphs and other silicate minerals. They include: | ||
*[[andalusite]], Al<sub>2</sub>SiO<sub>5</sub> | *[[andalusite]], Al<sub>2</sub>SiO<sub>5</sub> | ||
*[[sillimanite]], Al<sub>2</sub>SiO<sub>5</sub> | *[[sillimanite]], Al<sub>2</sub>SiO<sub>5</sub> | ||
| Line 44: | Line 50: | ||
*[[mica]]s, AB<sub>2-3</sub>(X, Si)<sub>4</sub>O<sub>10</sub>(O,F,OH)<sub>2</sub> | *[[mica]]s, AB<sub>2-3</sub>(X, Si)<sub>4</sub>O<sub>10</sub>(O,F,OH)<sub>2</sub> | ||
*[[garnet]]s, A<sub>3</sub>B<sub>2</sub>(SiO<sub>4</sub>)<sub>3</sub> | *[[garnet]]s, A<sub>3</sub>B<sub>2</sub>(SiO<sub>4</sub>)<sub>3</sub> | ||
| + | |||
| + | ==Uses of kyanite== | ||
| + | [[Image:BBBoxCar50Ft.jpg|thumb|230px|right|In [[Buckingham County, Virginia]] kyanite from the mine at [[Mt. Willis]] is transported by train on the [[Buckingham Branch Railroad]].]] | ||
| + | |||
| + | Kyanite is used primarily in refractory and ceramic products, including porcelain plumbing fixtures and dinnerware. It is also used in electrical insulators and abrasives. An interesting property of kyanite is that it undergoes an irreversible expansion when fired at high temperature. Kyanite has also been used as a gemstone, though this use is limited by its anisotropism and perfect cleavage. Finally, as with most minerals, kyanite is a collector's mineral. | ||
==Alternative names== | ==Alternative names== | ||
| Line 49: | Line 60: | ||
Kyanite has several alternative names, including '''disthene''', '''munkrudite''', and '''cyanite'''. White-gray kyanite is also called '''rhaeticite'''. | Kyanite has several alternative names, including '''disthene''', '''munkrudite''', and '''cyanite'''. White-gray kyanite is also called '''rhaeticite'''. | ||
| − | == | + | ==References== |
| − | + | ||
| + | * Deer, W.A., R.A. Howie, and J. Zussman. 1996. ''An Introduction to the Rock-Forming Minerals''. 2nd ed. Upper Saddle River, NJ: Prentice Hall. ISBN 0582300940. | ||
| + | |||
| + | * Farndon, John. 2006. ''The Practical Encyclopedia of Rocks & Minerals: How to Find, Identify, Collect and Maintain the World's best Specimens, with over 1000 Photographs and Artworks''. London: Lorenz Books. ISBN 0754815412. | ||
| + | |||
| + | * Klein, Cornelis, and Barbara Dutrow. 2007. ''Manual of Mineral Science''. 23rd ed. New York: John Wiley. ISBN 978-0471721574. | ||
| + | |||
| + | * Pellant, Chris. 2002. ''Rocks and Minerals''. Smithsonian Handbooks. New York: Dorling Kindersley. ISBN 0789491060. | ||
| + | |||
| + | * Schumann, Walter. 2006. ''Gemstones of the World'' 3rd ed. New York: Sterling. ISBN 1402740166. | ||
| − | + | * Shaffer, Paul R., Herbert S. Zim, and Raymond Perlman. 2001. ''Rocks, Gems and Minerals''. Rev. ed. New York: St. Martin's Press. ISBN 1582381321. | |
| − | == | + | == External links == |
| − | *[http://webmineral.com/data/Kyanite.shtml | + | * [http://webmineral.com/data/Kyanite.shtml Kyanite Mineral Data.] ''Webmineral.com''. Retrieved May 15, 2007. |
| − | *[http://www.mindat.org/min-2303.html | + | * [http://www.mindat.org/min-2303.html Kyanite.] ''Mindat.org''. Retrieved May 15, 2007. |
| − | *[http://mineral.galleries.com/minerals/silicate/kyanite/kyanite.htm Mineral Galleries | + | * [http://mineral.galleries.com/minerals/silicate/kyanite/kyanite.htm The Mineral Kyanite.] ''Amethyst Galleries''. Retrieved May 15, 2007. |
[[Category:Physical sciences]] | [[Category:Physical sciences]] | ||
Revision as of 23:32, 15 May 2007
| Kyanite | |
|---|---|
 |
|
| General | |
| Category | Mineral |
| Chemical formula | Al2SiO5 (aluminum silicate) |
| Identification | |
| {{{molweight}}} | |
| Color | Blue; also green, white, grey, black |
| Crystal habit | Columnar; fibrous |
| Crystal system | Triclinic |
| Cleavage | [100] Perfect, [010] Imperfect |
| Fracture | Brittle |
| Mohs Scale hardness | 4.5-5 parallel to one axis 6.5-7 perpendicular to that axis |
| Luster | Vitreous; Pearly |
| Refractive index | 1.71 - 1.75 |
| Pleochroism | Trichroic, colorless to pale blue to blue |
| Streak | White |
| Specific gravity | 3.56 - 3.67 |
| {{{density}}} | |
| Solubility | None |
| Diaphaneity | Transparent to translucent |
Kyanite, whose name derives from the Greek word kyanos, meaning blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and sedimentary rocks. Kyanite is a diagnostic mineral of the Blueschist Facies of metamorphic rocks.
Characteristics
Kyanite is a member of the aluminosilicate group of silicate minerals. It has two polymorphs: andalusite and sillimanite. Kyanite and its polymorphs have the same chemical formula, Al2SiO5, but they differ in crystalline structure.
Kyanite is strongly anisotropic, in that its hardness varies depending on its crystallographic direction. While this is a feature of almost all minerals, in kyanite this anisotropism can be considered an identifying characteristic.
Identifying traits
Kyanite's elongated, columnar crystals are usually a good first indication of the mineral, as well as its color (when the specimen is blue). Associated minerals are useful as well, especially the presence of the polymorphs or staurolite, which occur frequently with kyanite. However, the most useful characteristic in identifying kyanite is its anisotropism. If one suspects a specimen to be kyanite, verifying that it has two distinctly different hardnesses on perpendicular axes is a key to identification.
Associated minerals
Kyanite is usually found in association with its polymorphs and other silicate minerals. They include:
- andalusite, Al2SiO5
- sillimanite, Al2SiO5
- quartz, SiO2
- staurolite, Fe2Al9Si4O22(OH)2
- micas, AB2-3(X, Si)4O10(O,F,OH)2
- garnets, A3B2(SiO4)3
Uses of kyanite
Kyanite is used primarily in refractory and ceramic products, including porcelain plumbing fixtures and dinnerware. It is also used in electrical insulators and abrasives. An interesting property of kyanite is that it undergoes an irreversible expansion when fired at high temperature. Kyanite has also been used as a gemstone, though this use is limited by its anisotropism and perfect cleavage. Finally, as with most minerals, kyanite is a collector's mineral.
Alternative names
Kyanite has several alternative names, including disthene, munkrudite, and cyanite. White-gray kyanite is also called rhaeticite.
ReferencesISBN links support NWE through referral fees
- Deer, W.A., R.A. Howie, and J. Zussman. 1996. An Introduction to the Rock-Forming Minerals. 2nd ed. Upper Saddle River, NJ: Prentice Hall. ISBN 0582300940.
- Farndon, John. 2006. The Practical Encyclopedia of Rocks & Minerals: How to Find, Identify, Collect and Maintain the World's best Specimens, with over 1000 Photographs and Artworks. London: Lorenz Books. ISBN 0754815412.
- Klein, Cornelis, and Barbara Dutrow. 2007. Manual of Mineral Science. 23rd ed. New York: John Wiley. ISBN 978-0471721574.
- Pellant, Chris. 2002. Rocks and Minerals. Smithsonian Handbooks. New York: Dorling Kindersley. ISBN 0789491060.
- Schumann, Walter. 2006. Gemstones of the World 3rd ed. New York: Sterling. ISBN 1402740166.
- Shaffer, Paul R., Herbert S. Zim, and Raymond Perlman. 2001. Rocks, Gems and Minerals. Rev. ed. New York: St. Martin's Press. ISBN 1582381321.
External links
- Kyanite Mineral Data. Webmineral.com. Retrieved May 15, 2007.
- Kyanite. Mindat.org. Retrieved May 15, 2007.
- The Mineral Kyanite. Amethyst Galleries. Retrieved May 15, 2007.
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