noun
oligoclase
A mineral name; a type of plagioclase feldspar. Used in geological and mineralogical contexts.
灰曹長石は斜長石の一種で、ナトリウムを多く含む。
Oligoclase is a type of plagioclase feldspar that is rich in sodium.
The Japanese name 灰曹長石 is composed of 灰 (kai, 'ash', referring to its grayish color), 曹 (sō, here from 曹達, 'soda' i.e. sodium), and 長石 (chōseki, 'feldspar'). The exact historical derivation is uncertain; the spelling is conventionally associated with its composition and appearance.