Gneiss - Definition - Law Dictionary Home Dictionary Definition gneiss

Definition :

A crystalline rock consisting like granite of quartz feldspar and mica but having these materials especially the mica arranged in planes so that it breaks rather easily into coarse slabs or flags Hornblende sometimes takes the place of the mica and it is then called hornblendic gneiss or syenitic gneiss Similar varieties of related rocks are also called gneiss