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
- a laminated metamorphic rock comparable to granite
- A crystalline stone, consisting, like granite, of quartz, feldspar, and mica, but having these products, especially the mica, organized in airplanes, such that it breaks instead easily into coarse slabs or flags. Hornblende often takes the area of mica, and it's also then labeled as hornblendic / syenitic gneiss. Comparable types of relevant stones may called gneiss.
1757, from German Gneiss "variety of metamorphic stone," probably from Middle tall German gneist "spark" (so-called since the rock glitters), from Old tall German gneisto "spark" (contrast Old English gnast "spark," Old Norse gneisti).
(n.) A crystalline stone, consisting, like granite, of quartz, feldspar, and mica, but having these products, especially the mica, organized in planes, so that it breaks rather quickly into coarse slabs or flags. Hornblende often takes the place regarding the mica, and it is after that known as hornblendic / syenitic gneiss. Similar types of related rocks will also be called gneiss.
Bismuth occurs in metalliferous veins traversing gneiss or clay-slate, and is usually associated with ores of silver and cobalt.