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Granite (/ ˈ ɡ r æ n ɪ t / GRAN-it) is a coarse-grained intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous ...
A silicate mineral is generally an inorganic compound consisting of subunits with the formula [SiO 2+n] 2n−. Although depicted as such, the description of silicates as anions is a simplification. Balancing the charges of the silicate anions are metal cations, M x+. Typical cations are Mg 2+, Fe 2+, and Na +. The Si-O-M linkage between the ...
Most commonly, silicates are encountered as silicate minerals. For diverse manufacturing, technological, and artistic needs, silicates are versatile materials, both natural (such as granite, gravel, and garnet) and artificial (such as Portland cement, ceramics, glass, and waterglass).
The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent. [1] Granite and rhyolite are the most common silicic rocks. Silicic is the group of silicate magmas which will eventually crystallise a relatively small proportion of ferromagnesian silicates, such as amphibole, pyroxene, and biotite.
Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Molten felsic magma and lava is more viscous than molten mafic magma and lava. Felsic magmas and lavas have lower temperatures of melting and solidification than mafic magmas and lavas.
Granite plutons can be grouped into suites and super suites by their source regions, which in turn are interpreted by comparing their compositions. [9] This interpretation comes from the plotting of different element concentrations against the level of evolution of the granite, usually as percent silica or its magnesium to iron ratio.
Typical sial material, a Precambrian granite from St. Francois Mountains, Missouri, showing the potassium feldspar (felsic) matrix. In geology, sial is an antiquated [1] blended term for the composition of the upper layer of Earth's crust, namely rocks rich in aluminium silicate minerals.
Granite plutons can be grouped into suites and super suites by their source regions, which in turn are interpreted by comparing their compositions. This interpretation comes from the plotting of different element concentrations against the level of evolution of the granite, usually as percent silica or its magnesium to iron ratio.