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 Falls, Minnesota or over. Granite Falls, Minnesota Granite Falls is a city in Chippewa, Renville and Yellow Medicine counties in the State of Minnesota. The population was 2,897 at the 2010 census. It is the county seat of Yellow Medicine County. The Andrew John Volstead House, a National Historic Landmark, is located in Granite Falls. Granite Falls was platted in 1872. The city was named for deposits of granite rock in the area. A post office has been in operation at Granite Falls since 1870. Granite Falls was incorporated as a city in 1889. On July 25, 2000, the city of Granite