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Mineral symbols (text abbreviations) are used to abbreviate mineral groups, subgroups, and species, just as lettered symbols are used for the chemical elements. The first set of commonly used mineral symbols was published in 1983 and covered the common rock-forming minerals using 192 two- or three-lettered symbols. [ 1 ]
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.
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 ]
Monzogranite – Biotite granite rocks that are considered to be the final fractionation product of magma – A silica-undersaturated granite with <5% normative quartz; Monzonite – Igneous intrusive rock with low quartz and equal plagioclase and alkali feldspar – a plutonic rock with <5% normative quartz
The quartz percentage among felsic minerals in TTG rocks is usually larger than 20% but less than 60%. [1] In tonalite and trondhjemite, more than 90% of the feldspars are plagioclase, while in granodiorite, this number is between 65% and 90%. [1] Trondhjemite is a special kind of tonalite, with most of the plagioclase in the rock being ...
The name has come to be used most frequently as a textural term where it implies plagioclase rims around orthoclase in plutonic (intrusive) rocks. Rapakivi is a Finnish compound of "rapa" (meaning "mud" or "sand", while rapautua means "to erode") and "kivi" (meaning "rock"), [ 1 ] because the different heat expansion coefficients of the ...
Gabbro is known in the construction industry by the trade name of black granite. [31] However, gabbro is hard and difficult to work, which limits its use. [32] The term "indigo gabbro" is used as a common name for a mineralogically complex rock type often found in mottled tones of black and lilac-grey.
A larvikite quarry in Larvik, Norway, 2008 Polished larvikite (marketed as "Blue Pearl Granite"), showing labradorescence, is a popular decorative stone. Light larvikite with a polished surface Larvikite is an igneous rock , specifically a variety of monzonite , [ 1 ] notable for the presence of thumbnail-sized crystals of feldspar .