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Quartz gabbro

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Quartz gabbro is an intrusive rock with a composition intermediate between gabbro and tonalite. It is defined in the QAPF classification as coarse-grained igneous rock in which quartz makes up 5% to 20% of the QAPF mineral fraction, plagioclase makes up 90% or more of the total feldspar content, and the plagioclase is calcium-rich (%An > 50).[1][2][3]


  1. ^ Le Bas, M. J.; Streckeisen, A. L. (1991). "The IUGS systematics of igneous rocks". Journal of the Geological Society. 148 (5): 825–833. Bibcode:1991JGSoc.148..825L. CiteSeerX doi:10.1144/gsjgs.148.5.0825. S2CID 28548230.
  2. ^ "Rock Classification Scheme - Vol 1 - Igneous" (PDF). British Geological Survey: Rock Classification Scheme. 1: 1–52. 1999.
  3. ^ Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. pp. 139–143. ISBN 978-0-521-88006-0.