oligoclase

ol·i·go·clase  (l-g-kls, -klz, l-)

n.

See plagioclase.

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[oligo- + Greek klasis, cleavage (from kln, to break; see plagioclase).]

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oligoclase  (l-g-kls, l-)

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.

Thesaurus

Noun

1.

oligoclase - any of a series of triclinic feldspars that form rocks plagioclase dacite - a grey volcanic rock containing plagioclase and quartz and other crystalline minerals basalt - the commonest type of solidified lava; a dense dark grey fine-grained igneous rock that is composed chiefly of plagioclase feldspar and pyroxene feldspar, felspar - any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium albite, white feldspar - a widely distributed feldspar that forms rocks anorthite - rare plagioclastic feldspar occurring in many igneous rocks