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, Virginia Granite, Virginia Granite was an unincorporated community in Chesterfield County, Virginia. It was originally located along the Richmond and Danville Railroad five miles west of Manchester and about a mile south of the rapids of the James River along Powhite Creek. According to documents on file at the Library of Virginia, in April 1872, notice was published in Petersburg that Mathew Hall had been appointed postmaster of a new U.S. Post Office at Granite. Granite was named for the granite rock formations which underlie the rapids of the river at the geological fall line which begin downstream from the current