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[churt] /tʃɜrt/
a compact rock consisting essentially of microcrystalline quartz.
1670-80; origin uncertain
Related forms
cherty, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for chert
  • The sediments in this photo curve near the ends of chert pods.
  • chert tool stone often was heated first, to improve its flaking qualities.
  • They preferred rocks such as chert, a type of flint, that can be chipped precisely.
  • chert breaks into rounded surfaces with sharp edges.
British Dictionary definitions for chert


a microcrystalline form of silica usually occurring as bands or layers of pebbles in sedimentary rock. Formula: SiO2. Varieties include flint, lyddite (Lydian stone) Also called hornstone
Derived Forms
cherty, adjective
Word Origin
C17: of obscure origin
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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Word Origin and History for chert

"flint-like quartz," 1670s, of unknown origin. Apparently "a local term, which has been taken into geological use" [OED].

Online Etymology Dictionary, © 2010 Douglas Harper
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chert in Science
A hard, brittle sedimentary rock consisting of microcrystalline quartz. It is often reddish-brown to green but can also occur in a variety of other colors, especially white, pink, brown, or black. Chert often contains impurities such as calcium, iron-oxide, or the remains of silica-rich organisms. It usually occurs as nodules in limestone and dolomite and has curved fractures.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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