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Mafic enclave in granite rock, at Yosemite National Park Granite forms from silica-rich ( felsic ) magmas. Felsic magmas are thought to form by addition of heat or water vapor to rock of the lower crust , rather than by decompression of mantle rock, as is the case with basaltic magmas. [ 20 ]
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase ...
Alkali feldspar granite – Type of igneous rock rich in alkali feldspar; Ankaramite - Igneous rock belonging to basalt family; Anorthosite – Mafic intrusive igneous rock composed predominantly of plagioclase; Aplite – Fine-grained intrusive igneous rock type similar to granite; Basalt – Magnesium- and iron-rich extrusive igneous rock
Often the species of mafic minerals is included in the name, for instance, hornblende-bearing granite, pyroxene tonalite or augite megacrystic monzonite, because the term "granite" already assumes content with feldspar and quartz. The rock texture thus determines the basic name of a felsic rock. Close-up of granite from Yosemite National Park.
Mafic rocks have a relatively low silica content and are composed mostly of pyroxenes, olivines and calcic plagioclase. These rocks (basalt, gabbro) are usually dark coloured, and have a higher density than felsic rocks. Ultramafic rock is very low in silica, with more than 90% of mafic minerals (komatiite, dunite).
Its silica content (by one common classification) would make it a mafic rock in chemical terms, but an ultramafic rock in mineralogical terms, because it would be entirely composed of a mafic mineral. [6] Some examples of felsic rocks include granite and rhyolite, while examples of mafic rocks include gabbro and basalt. [1]
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in ...
Typical acidic rocks are granite or rhyolite. The term is used in chemical classification of igneous rock based on the content of silica (SiO 2 ). Due to the fact that chemical analyzes are not always available, especially during the fieldwork, classification based on the mineral (modal) composition is more often used (dividing the igneous ...