Definition from Wiktionary, the free dictionary
- (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.
- “Oligoclase” in David Barthelmy, Webmineral Mineralogy Database, 1997–.
- oligoclase mindat.org, Hudson Institute of Mineralogy, accessed 29 August 2016