Coarse-grained intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase.- Granite
500 related topics
That individual mica crystals can easily be split into extremely thin elastic plates.
It is particularly prominent in many granites, pegmatites, and schists, and "books" (large individual crystals) of mica several feet across have been found in some pegmatites.
Generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar.
The terms granite and granitic rock are often used interchangeably for granitoids; however, granite is just one particular type of granitoid.
One of the three main rock types, the others being sedimentary and metamorphic.
in some special circumstances they host important mineral deposits (ores): for example, tungsten, tin, and uranium are commonly associated with granites and diorites, whereas ores of chromium and platinum are commonly associated with gabbros.
Feldspars are a group of rock-forming aluminium tectosilicate minerals, containing sodium, calcium, potassium, or barium.
The perthitic textures in the alkali feldspars of many granites can be seen with the naked eye.
Complex inosilicate series of minerals.
Hornblende is most often confused with the pyroxene series and biotite mica, which are also dark minerals found in granite and charnockite.
Adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts.
Porphyritic intrusive rocks have a matrix with individual crystals easily distinguished with the eye, but one group of crystals appearing clearly much bigger than the rest, as in a porphyritic granite.
Sheet of rock that is formed in a fracture of a pre-existing rock body.
The range of compositions in a composite dike can go all the way from diabase to granite, as is observed in some dikes of Scotland and northern Ireland.
Textural term for an igneous rock consisting of coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass.
Porphyries may be aphanites or phanerites, that is, the groundmass may have microscopic crystals as in basalt, or crystals easily distinguishable with the eye, as in granite.
Early forming, relatively large and usually conspicuous crystal distinctly larger than the grains of the rock groundmass of an igneous rock.
In rapakivi granites, phenocrysts of orthoclase are enveloped within rinds of sodic plagioclase such as oligoclase.
Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%).