gneiss

/nahys/US // naɪs //UK // (naɪs) //

片麻岩,片麻石,片麻子,片麻黄

Definitions

n.名词 noun

1
- : a metamorphic rock, generally made up of bands that differ in color and composition, some bands being rich in feldspar and quartz, others rich in hornblende or mica.

Gneiss is a similar mixture, but characterised by the predominance of mica, and by its banded structure.
A course gneiss is the predominant rock, but is associated with garnetiferous mica-schists and much intrusive granite.
The former—mostly gneiss—is far more rugged and interesting, and there is infinitely more of the latter.
The tertiary formation is followed by an azoic formation of gneiss, mica slate, and phylada with large intrusions of granite.
Hannam operated the forge, and picks and drills were sent along for pointing; an outcrop of gneiss serving as an anvil.