Oligoclase meaning

ŏlĭ-gō-klās, -klāz, ōlĭ-
A white, gray, green or red variety of plagioclase feldspar that contains a higher proportion of sodium than calcium and is common in silica-rich igneous rocks.
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A plagioclase feldspar whose composition corresponds to 70 to 90 percent albite.
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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.
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(mineralogy) A plagioclase feldspar, the second member of the Albite-Anorthite solid solution series. Primarily found as small crystals in impure marble. Oligoclase contains a small amount of calcium substituting for some of the sodium in its formula. Oligoclase with reddish-golden inclusions found in Norway and Canada is called sunstone.
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Origin of oligoclase

  • oligo– Greek klasis cleavage (from klān to break plagioclase feldspar)

    From American Heritage Dictionary of the English Language, 5th Edition

  • From oligo- +"Ž clase

    From Wiktionary