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[pich-stohn] /ˈpɪtʃˌstoʊn/
a glassy volcanic rock having a resinous luster and resembling hardened pitch.
1775-85; translation of German Pechstein. See pitch2, stone Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for pitchstone
  • The rate of cooling is too rapid to permit crystallization, which results in the formation of obsidian and pitchstone.
  • Some of the later flows are also formed of obsidian and pitchstone through rapid cooling.
British Dictionary definitions for pitchstone


a dark glassy acid volcanic rock similar in composition to granite, usually intruded as dykes, sills, etc
Word Origin
C18: translation of German Pechstein
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Encyclopedia Article for pitchstone

a volcanic glass with a conchoidal fracture (like glass), a resinous lustre, and a variable composition. Its colour may be mottled, streaked, or uniform brown, red, green, gray, or black. It is formed by the rapid cooling of viscous lava or magma.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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