An igneous rock of granitic composition characterized by the presence of two types of alkali feldspar: a potassium-rich type displaying perthitic (see perthite) texture; and a sodium-rich type displaying antiperthitic texture. Subsolvus granites have a high water content, which depresses their liquidii sufficiently to intersect the subsolidus solvus surface and cause two extremes of feldspar composition to crystallize from the melt, instead of one intermediate-composition feldspar as in hypersolvus granites.