珪けい長ちょう岩がん

noun

felsite; felstone

A fine-grained igneous rock composed mainly of felsic minerals. Technical term used in geology and mineralogy.

• この地ち域いきの珪けい長ちょう岩がんは石せき英えいと長ちょう石せきを多おおく含ふくんでいる。

  The felsite in this area contains a lot of quartz and feldspar.