Origin of oligoclaseGerman oligoklas from Classical Greek oligos (see oligo-) + klasis, a fracture (see clastic), in contrast to orthoclase, because cleavage differs slightly from 90°
Origin of oligoclaseoligo- Greek klasis cleavage ( from klān to break ; see plagioclase feldspar . )
(usually uncountable, plural oligoclases)
- (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.
From oligo- +"Ž clase