- Igneous rock dominated by the light-coloured, silicon-and aluminum-rich minerals feldspar and quartz.The presence of these minerals gives felsic rock its characteristic light gray colour. The presence of small amounts of dark minerals rich in magnesium and iron produces slight colour variations. Typical felsic rocks include granite and rhyolite.
* * *igneous rock dominated by the light-coloured, silicon- and aluminum-rich minerals feldspar and quartz (qq.v.). The presence of these minerals gives felsic rock its characteristic light gray colour. The silica (SiO2) content of felsic rock is greater than about 60 percent by weight. Slight colour variations result from the presence of small amounts of mafic minerals (i.e., dark minerals rich in magnesium and iron). The colour index or volume percent of dark minerals is used as a macroscopic quantitative measure of felsic (or mafic) character. Typical felsic rocks include granite and its fine-grain extrusive equivalent, rhyolite. See also mafic rock.
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felsic rock — A general term for igneous rock containing abundant, light colored minerals (granite, etc); also applied to those minerals (quartz, feldspars, feldspathoids, muscovite) as a group. Compare: mafic rock. GG … Glossary of landform and geologic terms
Felsic — is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. The term combines the words feldspar and silica. Felsic minerals are… … Wikipedia
rock — rock1 rockless, adj. rocklike, adj. /rok/, n. 1. a large mass of stone forming a hill, cliff, promontory, or the like. 2. Geol. a. mineral matter of variable composition, consolidated or unconsolidated, assembled in masses or considerable… … Universalium
Rock — /rok/, n. a male given name. * * * I In geology, a naturally occurring and coherent aggregate of minerals. The three major classes of rock igneous, sedimentary, and metamorphic are based on the processes that formed them. These three classes are… … Universalium
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felsic and mafic rocks — ▪ igneous rock division of igneous rocks (mafic rock) on the basis of their silica content. Chemical analyses of the most abundant components in rocks usually are presented as oxides (oxide) of the elements; igneous rocks typically consist… … Universalium
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felsic — ALASKA VOLCANO OBSERVATORY GLOSSARY An igneous rock having abundant light colored minerals … Glossary of volcanic terms
Igneous rock — Geologic provinces of the world (USGS) Shield … Wikipedia
igneous rock — Any of various crystalline or glassy, noncrystalline rocks formed by the cooling and solidification of molten earth material (magma). Igneous rocks comprise one of the three principal classes of rocks, the others being metamorphic and sedimentary … Universalium