oligoclase

American  

[ol-i-goh-kleys] / ˈɒl ɪ goʊˌkleɪs /

noun

Mineralogy.

1. a kind of plagioclase feldspar occurring commonly in white crystals, sometimes shaded with gray, green, or red.

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oligoclase British  

/ ˈɒlɪɡəʊˌkleɪs /

noun

1. a white, bluish, or reddish-yellow feldspar mineral of the plagioclase series, consisting of aluminium silicates of sodium and calcium. Formula: NaAlSi 3 O 8 .CaAl 2 Si 2 O 8

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oligoclase Scientific  

/ ŏl′ĭ-gō-klās′,ō′lĭ- /

1. 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)AlSi ₂ O ₈ .

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Etymology

Origin of oligoclase

First recorded in 1825–35; oligo- + -clase

Example Sentences

Of their minerals felspar Is usually the most abundant, and is principally labradorite and bytownite, though anorthite occurs in some, while oligoclase and orthoclase have been found in others.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 4 "G" to "Gaskell, Elizabeth" by Various

Aventurine and moonstone varieties occur, though these special appearances are more usually displayed by the oligoclase and orthoclase felspars respectively.

From The Project Gutenberg Encyclopedia Volume 1 of 28 by Project Gutenberg

The felspar of the granulites is mostly orthoclase or cryptoperthite; microcline, oligoclase and albite are also common.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 "Gordon, Lord George" to "Grasses" by Various

He found oligoclase and pyroxene on the trachytes of Chimborazo, Popocatepetl,xlviii Colima, Tunguragua, Purac�, Paramo de Ruiz, and the Peak of Teneriffe, which has recently been accurately examined by Mr. Charles Deville.

From Narrative of the Circumnavigation of the Globe by the Austrian Frigate Novara, Volume I (Commodore B. Von Wullerstorf-Urbair,) Undertaken by Order of the Imperial Government in the Years 1857, 1858, & 1859, Under the Immediate Auspices of His I. and R. Highness the Archduke Ferdinand Maximilian, Commander-In-Chief of the Austrian Navy. by Scherzer, Karl Ritter von

To these succeeded during the Pliocene epoch still more highly silicated rocks of trachytic type, consisting of sanidine and oligoclase trachytes.

From Volcanoes: Past and Present by Hull, Edward