• synonyms


  1. any compact sedimentary rock composed mainly of clay materials; clay stone.
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Origin of argillite

1785–95; < Latin argill(a) argil + -ite1
Related formsar·gil·lit·ic [ahr-juh-lit-ik] /ˌɑr dʒəˈlɪt ɪk/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for argillite

Historical Examples of argillite

  • It is very significant that we never find one where the workman used both flint and argillite.

    The Prehistoric World

    E. A. Allen

  • Next above the Altyn lies thirty-four hundred feet of Appekunny argillite, or dull-green shale.

    The Book of the National Parks

    Robert Sterling Yard

  • The fact that argillite continued in use until the very last does not affect this conclusion.

  • Sandstone may be converted into quartzite, and shale into argillite, a compact, massive clay rock.

    The Elements of Geology

    William Harmon Norton

  • Here anthracitiferous coal is found in beds of argillite and sandstone.

British Dictionary definitions for argillite


  1. any argillaceous rock, esp a hardened mudstone
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Derived Formsargillitic (ˌɑːdʒɪˈlɪtɪk), adjective

Word Origin for argillite

C18: from Latin argilla clay (from Greek argillos) + -ite 1
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

argillite in Science


  1. A highly compacted sedimentary or slightly metamorphic rock consisting primarily of particles of clay or silt. Argillite differs from mudstone in that it does not have the same fine laminations, and from shale and slate in that it is not fissile.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.