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. Often observed as a certain indicator for continental rift basin related volcanicity.
References
Peralkaline rock Wikipedia(Text) CC BY-SA