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Granite (/ ˈɡrænɪt / GRAN-it) is a coarse-grained (phaneritic) 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.
W.N. Flynt Granite Co., in Monson, Massachusetts, a granite quarry that opened in 1809 and operated until 1935. By 1888, the company employed over 200 workers, and produced about 30,000 tons of granite per year. Quincy Quarries Reservation, in Quincy, Massachusetts, producer of granite from 1826 to 1963, including for the Bunker Hill Monument.
Igneous rock. Monzogranite (Col des Croix, Haute-Saône, France) QAPF diagram with the Monzogranite field highlighted. Monzogranite is a plutonic rock that occupies the middle of the QAPF diagram, consisting of between 20-60% quartz, and of the remainder, between 35-65% alkali feldspar and the remainder plagioclase.
Chert – Hard, fine-grained sedimentary rock composed of cryptocrystalline silica. Claystone – Clastic sedimentary rock composed primarily of clay-sized particles. Coal – Combustible sedimentary rock composed primarily of carbon. Conglomerate – Sedimentary rock composed of smaller rock fragments.
The Idaho Batholith is a granitic and granodioritic batholith of Cretaceous - Paleogene age that covers approximately 25,000 square kilometres (9,700 sq mi) of central Idaho and adjacent Montana. The batholith has two lobes that are separate from each other geographically and geologically. The Bitterroot lobe is the smaller lobe and the larger ...
A-type granite. A-type granite is a particular category of the S-I-A-M or 'alphabet' system which classifies granitoids and granitic rock by their photoliths or source. [1][2] The 'A' stands for Anorogenic or Anhydrous, as these granites are characterized by low water content and a lack of orogenic or transitional tectonic fabric. [3]
I-type granite. I-type granites are a category of granites originating from igneous sources, first proposed by Chappell and White (1974). [1] They are recognized by a specific set of mineralogical, geochemical, textural, and isotopic characteristics that indicate, for example, magma hybridization in the deep crust. [2]
Rhyolite (/ ˈraɪ.əlaɪt / RY-ə-lyte) [1][2][3][4] is the most silica -rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase.