• synonyms


  1. a compact rock consisting essentially of microcrystalline quartz.
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Origin of chert

First recorded in 1670–80; origin uncertain
Related formschert·y, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for chert

Historical Examples

  • Seven specimens were of basalt and one each of chert and porphyry.

    The Topanga Culture Final Report on Excavations, 1948

    A. E. Treganza

  • The chert has sometimes the appearance of calcedony, and is finely striped.

  • In the same limestone there are enormous beds of chert, agates, and carnelians.

  • Nodules and layers of "chert" (an impure kind of flint) occur in it, whilst in places it forms a hard rock called "firestone."

  • Limestones lose their calcium carbonate by solution, leaving only clay with fragments of quartz or chert as impurities.

British Dictionary definitions for chert


  1. a microcrystalline form of silica usually occurring as bands or layers of pebbles in sedimentary rock. Formula: SiO 2 . Varieties include flint, lyddite (Lydian stone)Also called: hornstone
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Derived Formscherty, 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

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].

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Online Etymology Dictionary, © 2010 Douglas Harper

chert in Science


  1. 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.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.