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Silicic is the group of silicate magmas which will eventually crystallise a relatively small proportion of ferromagnesian silicates, such as amphibole, pyroxene, and biotite. The main constituents of a silicic rock will be minerals rich in silica-minerals, like silicic feldspar or even free silica as quartz .
Magma can be found in the mantle or molten crust. Magma (from Ancient Greek μάγμα (mágma) 'thick unguent') [1] is the molten or semi-molten natural material from which all igneous rocks are formed. [2]
Lithium aluminium silicate mineral spodumene. Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. [1] [2] [3] In mineralogy, silica (silicon dioxide, SiO 2) is usually considered a silicate mineral rather than an ...
Intermediate composition magma, such as andesite, tends to form cinder cones of intermingled ash, tuff and lava, and may have a viscosity similar to thick, cold molasses or even rubber when erupted. Felsic magma, such as rhyolite, is usually erupted at low temperature and is up to 10,000 times as viscous as basalt. Volcanoes with rhyolitic ...
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.
Fractional crystallization in silicate melts is complex compared to crystallization in chemical systems at constant pressure and composition, because changes in pressure and composition can have dramatic effects on magma evolution.
Mafic magma dominated the seafloor at around 3.9 Ga during the Hadean-Archean transition. [26] Due to rapid silicification, the felsic continental crust began to form. [ 27 ] In the Archean, the continental crust was composed of tonalite–trondhjemite–granodiorite (TTG) as well as granite– monzonite – syenite suites.
Solidified lava on the Earth's crust is predominantly silicate minerals: mostly feldspars, feldspathoids, olivine, pyroxenes, amphiboles, micas and quartz. [6] Rare nonsilicate lavas can be formed by local melting of nonsilicate mineral deposits [7] or by separation of a magma into immiscible silicate and nonsilicate liquid phases. [8]