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 spiny lizard Granite spiny lizard The granite spiny lizard (Sceloporus orcutti) is a species of phrynosomatid lizard. The epithet, "orcutti", honors American naturalist Charles Russell Orcutt (1864–1929), who collected the type specimen in San Diego County, California. It is endemic to southern California in the United States and Baja California in Mexico. The granite spiny lizard is snout-to-vent length. Maximum total length including the tail is . Its dorsal scales are strongly keeled and pointed on its body and tail. It has a wide purple mid-dorsal stripe. The males of the species have yellow-green and blue-centered scales on the body; juveniles and