Granophyres are alkali feldspar and quartz rocks that may represent the most differentiated portions of mafic intrusions. The granophyre in the photo above (field of view 1.5 mm) shows altered sodic plagioclase and clear quartz, in some cases intergrown to form myrmekite.
Granophyres form small sills and dikes in highly differentiated, layered intrusions.Petrography Home Minerals List Rocks List