斜しゃ長ちょう石せきしゃちょうせきMeanings1nounplagioclase feldsparmineralogyTechnical mineralogy term for a series of feldspar minerals. Not common in everyday conversation.斜しゃ長ちょう石せきは火か成せい岩がんによく含ふくまれる鉱こう物ぶつです。Plagioclase feldspar is a mineral commonly found in igneous rocks.