Granite may have more alkali feldspar, whereas a granite derived from partial melting of metaigneous rocks may be richer in plagioclase. It is on this basis that the modern "alphabet" classification schemes are based. The letter-based Chappell & White classification system was proposed initially to divide granites into I-type (igneous source) granite and S-type (sedimentary sources). Both types are produced by partial melting of crustal rocks, either metaigneous rocks or metasedimentary rocks. M-type granite was later proposed to cover those granites that were clearly sourced from crystallized mafic magmas, generally sourced from the mantle. However, this proposal has been rejected by
Granite Mountain (Arizona) to interior chaparral. Granite Mountain is a nesting site for the peregrine falcon ("Falco peregrinus"), and the climbing area on the south face is periodically closed to rock climbing, typically from February 1 until July 15 each year. Granite Mountain (Arizona) Granite Mountain () is a mountain located in Yavapai County, Arizona that covers roughly 12 square miles (31 km). It was once known as Mount Gurley, for the first governor of the Arizona Territory, John A. Gurley. Its southwest face has a sheer granite cliff approximately 500 feet (150 m) high that is one of the best locations for