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[ol-i-goh-kleys] /ˈɒl ɪ goʊˌkleɪs/
noun, Mineralogy
a kind of plagioclase feldspar occurring commonly in white crystals, sometimes shaded with gray, green, or red.
1825-35; oligo- + -clase Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for oligoclase
  • Calcic oligoclase commonly has faint euhedral oscillatory zoning but is also highly filled with epidote.
  • Most crystals are andesine, but the composition ranges from oligoclase to labradorite.
British Dictionary definitions for oligoclase


a white, bluish, or reddish-yellow feldspar mineral of the plagioclase series, consisting of aluminium silicates of sodium and calcium. Formula: NaAlSi3O8.CaAl2Si2O8
Word Origin
C19: from oligo- + -clase
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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oligoclase in Science
  (ŏl'ĭ-gō-klās', ō'lĭ-)   
A white to gray triclinic mineral of the plagioclase feldspar group. Oligoclase occurs in igneous rocks with a relatively high silica content, such as granite. Chemical formula: (Na,Ca)(Al,Si)AlSi2O8.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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