Granitic pegmatites have been a focal point of research by petrologists and mineralogists for over a century. Mineralogical interest stems from the diversity of rare minerals that some pegmatites contain. Petrologic efforts are aimed at resolving the processes or agents that produce the complex textures and spatial heterogeneity that distinguish pegmatites from granites. Much of the scientific study of pegmatites has been motivated by exploration for the economic commodities they provide. Pegmatites yield quartz, feldspars, and micas for industrial uses; strategic rare metals for electronic, aerospace, and energy applications; and many of the world's finest gem and mineral specimens.