Gneiss

Gneiss

Back to Encyclopedia

Gneiss is one of the most popular and common rock types littered in the environment because of how they are formed. These materials are formed from either of Sedimentary or Igneous rocks, and this is why their presence in nature is in large quantities compared to other rock materials. When these sedimentary or igneous rocks are metamorphosed probably due to high grade temperature changes or environmental reasons, Gneiss is formed! Most presentation of Gneiss rocks come in medium and sometimes coarse foliated forms. They are recrystallized but are, however, deficient of chlorites, micas and platy minerals as these usually occur in other crystallized materials.

The fact that Gneiss stems from either of the sedimentary and igneous rock types ensured the different groupings of the Gneiss rock types. Gneiss rock types are formed by the temperature and environmental changes on igneous rocks, which are called, Orthognesis. Those formed from such thermal changes on Sedimentary rocks are known as Paragneiss. Hence the Gneiss materials that show up in the environment are either Orthogneiss or Paragneiss and determination or classification of which origin the rock is of is possible through chemical and physical examination. This examination of course is the responsibility of the soil technicians and geologists whose duty it is by training.

Gneiss is a very popular and common rock type and large deposits can be found in the Rocky Mountains, the Piedmont, New England as well as the Adirondacks. The foliation and Schistosity are the most prominent distinguishable features between Gneiss and Schist. The foliation of Gneiss is well developed, but its cleavage and schistosity are poorly developed; Schist, however, is the opposite. Gneiss is coarse as against the finer physical property of Schist, and this is because of the interaction of the minerals within the Gneiss as they reacted to the temperature and other changes at the time of formation. These minerals, however, bear close semblance to those of granite.

Additional Resources

Glass Worktops   Granite   Granite Uses

 
 
 
Site Map | Login | Privacy Statement | Copyright 2018 Stone Hub Ltd t/a The Worktop Factory