oligoclase

IPA: oʊɫɪgʌkɫeɪs

(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.

Examples of "oligoclase" in Sentences

The plagioclase is sodium rich, usually albite or oligoclase.
Myrmekitic textures occur within oligoclase within the garnet zone.
The plagioclase feldspar oligoclase also produces moonstone specimens.
Oligoclase is a high sodium feldspar crystallizing in the triclinic system.
Oligoclase is a rock forming mineral belonging to the plagioclase feldspars.
They are commonly oligoclase, and sometimes assume branching or feathery forms.
Oligoclase and biotite schist have also been pushed to the surface of the Earth.