Quartzolite

Quartzolite or silexite is an intrusive igneous rock, in which the mineral quartz 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]

Not to be confused with quartzite or silex.
Quartzolite at the Q vertex of the QAPF diagram for plutonic rocks

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]

Examples

Formation

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 Granite pluton 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.[18]

References
  1. Le Maitre, R. W. (editor) (2002). Igneous Rocks:A Classification and Glossary of Terms (2nd edition). Cambridge: Cambridge University Press. ISBN 978-0-521-66215-4.CS1 maint: extra text: authors list (link)
  2. "Quartzolite". BGS Rock Classification Scheme. British Geological Survey. Retrieved 20 November 2016.
  3. "Definition of silexite". mindat.org. Retrieved 20 November 2016.
  4. Lishmund, S.R. (1974). "The Torrington silexite deposits". Geological Survey of New South Wales: Quarterly Notes. 17: 3–6.
  5. Fraser, Dean (2013). "Ackley Mo-Sn-F-W" (PDF). Newfoundland & Labrador: Explore The Opportunities. Matty Mitchell Prospectors Resource Room. Retrieved 21 November 2016.
  6. Klominsky, Josef; Fediuk, Ferry; Veselovsky, Frantisek; Schovanek, Pavel; Jarchovsky, Tomas; Taborsky, Zdenìk (2003). "Topazový Kvarcolit (Greisen) u Chrastavy v Severních Čechách Jako Metalogenetický Indikátor W-Sn Mineralizace" [Topaz quartzolite (greisen) near Chrastava in Northern Bohemia – metallogenic indicator of the W-Sn mineralization] (PDF). Zprávy o geologických výzkumech v roce (in Czech): 112–114. ISSN 0514-8057.
  7. Zozulya, D.; Lyalina, L.; Macdonald, R.; Dzierzanowski, P. (2014). "Genesis and alteration mechanisms of britholite group minerals from ore bodies related to the Keivy peralkaline granite-nepheline syenite complex, Kola Peninsula, NW Russia". Workshop on accessory minerals, at University of Warsaw. Retrieved 22 November 2016.
  8. Gillespie, M.R.; Styles, M.T. (1999). "BGS Rock Classification Scheme, Volume 1: Classification of igneous rocks". British Geological Survey. p. 10. Retrieved 19 November 2016.
  9. Schumann, Walter (1993). Handbook of Rocks, Minerals, and Gemstones. Boston: Houghton-Mifflin Company. p. 198. ISBN 978-0-395-51138-1.
  10. Neuendorf, K.K.E.; Mehl, Jr., J.P.; Jackson, J.A. (editors) (2005). Glossary of Geology (5th edition). Alexandria, Virginia: American Geological Institute. p. 530. ISBN 978-3642066214.CS1 maint: extra text: authors list (link)
  11. Manutchehr-Danai, M. (2009). "Silexite". Dictionary of Gems and Gemology (3rd edition). Berlin: Springer. p. 778. doi:10.1007/978-3-540-72816-0_19824. ISBN 978-3-540-72795-8.
  12. Jackson, Norman J.; Douch, Colin J. (1986). "Jabal Hamra REE-mineralized silexite, Hijaz region, Kingdom of Saudi Arabia". Journal of African Earth Sciences. 4: 269–274. doi:10.1016/S0899-5362(86)80088-4.
  13. Miller, William J. (1919). "Pegmatite, Silexite, and Aplite of Northern New York". The Journal of Geology. 27: 28–54. doi:10.1086/622638.
  14. 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.
  15. Shokouhian Rad, A . R.; Kazemi Koohbanani, Hadi; Kazemi Koohbanani, S.; Kazemi Koohbanani, N. (2014). "Petrology and Petrogenesis of Intrusive in North-East Saveh, Iran" (PDF). International Journal on Technical and Physical Problems of Engineering. 6: 6–11. ISSN 2077-3528.
  16. 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
  17. "Topaz" (PDF). Industrial Mineral Opportunities. NSW Department of Primary Industries. Retrieved 23 November 2016.
  18. Skinner, Mike (2015). "The Torrington Project" (PDF). Top Tung. Retrieved 23 November 2016.
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