gneiss
Sign in to saveGneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under pressures ranging from 2 to 15 kbar, sometimes even more, and temperatures over 300 °C (572 °F). Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct cleavage.
AI overview
Gneiss is a common metamorphic rock created when existing igneous or sedimentary rocks are subjected to extreme heat and pressure deep underground. It's recognizable by its distinctive banded appearance, with alternating stripes of darker and lighter colors, and forms under conditions involving pressures of 2 to 15 kilobars or more and temperatures exceeding 300°C.
AI-generated from the Wikipedia summary — may contain errors.
Key facts
- Rock.name
- Gneiss
- Rock.type
- Metamorphic
- Rock.image
- Gneiss.jpg
- Rock.caption
- Sample of gneiss exhibiting "gneissic banding"
via Wikipedia infobox
Article
15 sectionsContents
- Description
- Gneissic banding
- Augen gneiss
- Migmatite
- Occurrences
- Granite-greenstone belts
- Gneiss domes
- Examples
- Etymology
- Uses
- See also
- References
- Citations
- Further reading
- External links
Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under pressures ranging from 2 to 15 kbar, sometimes even more, and temperatures over 300 °C (572 °F). Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct cleavage.
Gneisses are common in the ancient crust of continental shields. Some of the oldest rocks on Earth are gneisses, such as the Acasta Gneiss.