Hypersolvus

In hypersolvus granites, crystallization at relatively low water pressures results in the formation of a single feldspar as opposed to subsolvus granites in which two distinct types of feldspar are present.

The distinctive character of feldspar in this kind of granite is to present exsolution textures. That is because the high temperature feldspar was ternary (i.e. contained comparable parts of the Ca, Na, K components) and was later dissociated during the cooling phase into K-rich parts and Na,Ca-rich parts, inside the frame and shape of the initial crystal.