Quartzolite or silexite is an intrusiveigneous rock, in which the mineralquartz is more than 90% of the rock's felsic mineral content, with feldspar at up to 10%.[1]: 135 [2] Typically, quartz forms more than 60% of the rock,[3] the rest being mostly feldspar although minor amounts of mica or amphibole may also be present.[2] Quartzolite occurs as dykes, sills, veins, bosses and segregation masses;[3][4] it is also found in association with greisen and pegmatite.[5][6][7] Quartzolite is an extremely rare type of rock.[8] No extrusive rock equivalent of quartzolite is known.[9]
Synonyms
The use of the synonym "silexite" is discouraged because it is the French word for chert, which is a sedimentary rock.[10] Other less common synonyms are "igneous quartz" and "peracidite".[11]
Some occurrences of quartzolite are unlikely to have an entirely igneous origin;[8] for example, two types of quartzolite that are associated with deposits of topaz in and around the Mole Granitepluton in Torrington, NSW, are believed to have formed in different ways. One type forms dykes and sills in the granite and in the surrounding metamorphic rocks. The other type has remnants of an earlier granite texture and is found on the outer edges of part of the pluton.[19]
References
^ abLe Maitre, R. W. (editor) (2002). Igneous Rocks:A Classification and Glossary of Terms (2nd ed.). Cambridge: Cambridge University Press. ISBN978-0-521-66215-4. {{cite book}}: |author= has generic name (help)
^Schumann, Walter (1993). Handbook of Rocks, Minerals, and Gemstones. Boston: Houghton-Mifflin Company. p. 198. ISBN978-0-395-51138-1.
^Neuendorf, K.K.E.; Mehl, Jr., J.P.; Jackson, J.A. (editors) (2005). Glossary of Geology (5th ed.). Alexandria, Virginia: American Geological Institute. p. 530. ISBN978-3642066214. {{cite book}}: |first3= has generic name (help)
^Li, Huaqin; Chen, Fuwen (2002). "Chronology and origin of Au-Cu deposits related to paleozoic intracontinental rifting in West Tianshan Mountains, NW China". Science in China Series B: Chemistry. 45: 108–120. doi:10.1007/BF02932212.
^Mair, B.F. (1987). "The Geology of South Georgia: VI. Larsen Harbour Formation". British Antarctic Survey Scientific Reports. 111: 1–60.
^Greenberg, R.M.; Miranda, E. (2009), "Strain localization in granodiorite mylonites: a microstructural and electron backscatter diffraction (EBSD) study of the South Mountains core complex, Arizona", AGU Fall Meeting Abstracts, 2009: T33A–1859, Bibcode:2009AGUFM.T33A1859G
^"Topaz"(PDF). Industrial Mineral Opportunities. NSW Department of Primary Industries. Retrieved 23 November 2016.