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[sil-uh-muh-nahyt] /ˈsɪl ə məˌnaɪt/
a mineral, aluminum silicate, Al 2 SiO 5 , occurring in the form of long, slender, and often fibrous crystals.
Also called fibrolite.
1825-30; named after B. Silliman; see -ite1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for sillimanite
  • Older parts of unit are characterized by an abundance of feldspar and local sillimanite.
  • Rare minerals such as garnets, sillimanite, staurolite or andalusite can be common in places.
  • Rare minerals such as garnets, staurolite, or sillimanite can be abundant locally.
British Dictionary definitions for sillimanite


a white, brown, or green fibrous mineral that consists of aluminium silicate in orthorhombic crystalline form and occurs in metamorphic rocks. Formula: Al2SiO5
Word Origin
C19: named after Benjamin Silliman (1779–1864), US chemist
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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sillimanite in Science
A usually white, pale-green or brown orthorhombic mineral occurring as long, slender, fibrous crystals in metamorphic rocks. It is a polymorph of andalusite and kyanite, but can form at higher temperatures than either of these. Chemical formula: Al2SiO5.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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