An agpaitic rock is a peralkaline igneous rock, typically nepheline syenite or phonolite. Characteristics include complex silicates containing zirconium, titanium, sodium, calcium, the rare-earth elements, and fluorine. Agpaites are unusually rich in rare and obscure minerals such as eudialyte, wöhlerite, loparite, astrophyllite, lorenzenite, catapleiite, lamprophyllite, and villiaumite (NaF). Notice the sodaic (Na) constituent of these minerals. Sodalite is typically present, but not diagnostic. Less alkaline igneous rocks in which zircon, titanite, and ilmenite are characteristic are called miaskitic.
Agpaitic rocks were first described for an occurrence in the Ilimaussaq complex of southwest Greenland in 1811. Agpaitic rocks are present in the Lovozero and Khibiny Massif complexes of the Kola Peninsula, in Mont Saint-Hilaire, Quebec, Canada, in addition to the type locality of Ilimaussaq.
- http://www.minersoc.org/pages/Archive-MM/Volume_39/39-306-729.pdf Archived 2014-04-08 at the Wayback Machine Edgar, A. D., On the use of the term 'Agpaitic', MINERALOGICAL MAGAZINE, JUNE I974, VOL. 39, PP. 729–30.
- http://minmag.geoscienceworld.org/cgi/content/abstract/61/4/485 Henning Sorensen, The agpaitic rocks; an overview, Mineralogical Magazine; August 1997; v. 61; no. 4; p. 485–498.