989,925,179 visitors served.
989,925,179 visitors served. |
|
 Dictionary/ thesaurus |  Medical dictionary |  Legal dictionary |  Financial dictionary |  Acronyms |  Idioms |  Encyclopedia |  Wikipedia encyclopedia | ? |
gneiss |
Also found in: Dictionary/thesaurus, Wikipedia, Hutchinson | 0.03 sec. |
|
gneiss (nīs), coarse-grained, imperfectly foliated, or layered, metamorphic rock rock, aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and ..... Click the link for more information. . Gneiss is characterized by alternating light and dark bands differing in mineral composition and having coarser grains than those of schist. The light bands of gneiss are generally composed of quartz quartz, one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO2. ..... Click the link for more information. and feldspar feldspar (fĕl`spär, fĕld`–) or felspar ..... Click the link for more information. . Hornblende, biotite mica, garnet, or graphite commonly form the dark bands. Gneisses result from the metamorphism of many igneous or sedimentary rocks, and are the most common types of rocks found in Precambrian regions. Gneiss is found in New England, the Piedmont, the Adirondacks, and the Rocky Mts. Some gneisses are used as facing stone on buildings. gneissMedium- to coarse-grained metamorphic rock with parallel, somewhat irregular banding that has little tendency to split along planes. Gneiss is the principal rock over extensive metamorphic terrains. Orthogneiss is formed by the metamorphism of igneous rocks; paragneiss results from the metamorphism of original sedimentary rocks. Pencil gneiss contains rod-shaped individual minerals or segregations of minerals, and augen gneiss contains large lenticular mineral grains or mineral aggregates having the appearance of eyes scattered through the rock. |
|
? Mentioned in | ? References in periodicals archive | |
|---|---|---|
Field evidence for this ancient crust is limited to a few remnants of supracrustal and plutonic rocks preserved in the Nuvvuagittuq belt and rare enclaves of tonalitic gneiss. It includes bedded limestone, dolomite, shale, slate, sandstone, marble, flagstone banded gneiss, massive white to red granite and black anorthsite. All of the remaining samples were comprised of variations of the bulk host lithology of garnetiferrous, biotitic gneiss. |
 |
| Free Tools: |
For surfers:
Browser extension |
Word of the Day |
Help
For webmasters: Free content NEW! | Linking | Lookup box | Double-click lookup | Partner with us |
|
|---|
Disclaimer |
Privacy policy |
Feedback | Copyright © 2008 Farlex, Inc.
Printer friendly
Cite / link
Email
Feedback
gneiss
