What's the difference between gneiss and gneissoid?
Gneiss
Definition:
(n.) 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 / syenitic gneiss. Similar varieties of related rocks are also called gneiss.
Example Sentences:
(1) Houses located on a granite, ortho-gneiss or verrucano subsoil have a cellar 222Rn level that is on the average 4.4 times higher than houses which are built on grey-schist or sediments.
(2) These include thermophilic and mesophilic oak-forest communities on loess and communities of acid oak forests on gneiss.
Gneissoid
Definition:
(a.) Resembling gneiss; having some of the characteristics of gneiss; -- applied to rocks of an intermediate character between granite and gneiss, or mica slate and gneiss.