Nepheline-bearing gabbro explained

Nepheline-bearing gabbro is an intrusive rock with a composition intermediate between gabbro and nepheline gabbro. It is defined in the QAPF classification as coarse-grained igneous rock in which feldspathoids makes up 0% to 10% of the QAPF mineral fraction and are predominantly nepheline; plagioclase makes up 90% or more of the total feldspar content; and the plagioclase is calcium-rich (%An > 50). ^{[1] [2] [3]}

Notes and References

1. Le Bas. M. J.. Streckeisen. A. L.. The IUGS systematics of igneous rocks. Journal of the Geological Society. 148. 5. 825–833. 10.1144/gsjgs.148.5.0825. 1991JGSoc.148..825L. 1991. 10.1.1.692.4446. 28548230.
2. 1999. Rock Classification Scheme - Vol 1 - Igneous. British Geological Survey: Rock Classification Scheme. 1. 1–52.
3. Book: Philpotts . Anthony R. . Ague . Jay J. . Principles of igneous and metamorphic petrology . 2009 . Cambridge University Press . Cambridge, UK . 978-0-521-88006-0 . 2nd . 139-143.