felsic

1. (petrology) Enriched in minerals predominantly composed of the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.Examples: "Much of the southern half of the southeastern body is a mafic syenite, slightly more felsic than the shonkinite."; "Within comagmatic suites, successively younger granitoids are commonly, but not invariably, more felsic, representing progressively lower temperature mineral assemblages."; "The Claret Creek Supersuite granites are a little more felsic (65-77% SiO₂), and are chemically distinctive, having higher Al₂O₃, CaO, Na₂O and Sr, and lower K₂O, Rb, Th and U than the granites of the Almaden Supersuite."Synonyms: acidic, sialic, silicic