Peralkaline rock

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Peralkaline rocks include those igneous rocks which have a deficiency of aluminium such that sodium and potassium are in excess of that needed for feldspar. The presence of aegerine (sodium pyroxene) and riebeckite (sodium amphibole) are indicative of peralkaline conditions.[1] An example is the peralkaline granite that forms the islet of Rockall in the North Atlantic Ocean.[2]

Peralkaline rocks are indicative of continental rift basin-related volcanicity, for example the peralkaline rhyolite lavas of the East African Rift in central Kenya.[3]

See also[edit]


  1. ^ Dutch, Steven (2009). "Classification of Igneous Rocks". Retrieved 15 September 2009. 
  2. ^ Sutherland, D. S. (editor) (1982). Igneous Rocks of the British Isles. Chichester: John Wiley and Sons. ISBN 0-471-27810-6. 
  3. ^ Scaillet, Bruno; Macdonald, Ray (2003). "Experimental Constraints on the Relationships between Peralkaline Rhyolites of the Kenya Rift Valley". Journal of Petrology. 44 (10): 1867–1894. doi:10.1093/petrology/egg062.