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
Rock of Ages Corporation natural stone producer, announced the acquisition of Swenson Granite and Rock of Ages Corporation to become the largest producer of marble and granite in North America. This also includes the Canadian division of Rock of Ages Corporation, located in Stanstead, Quebec, along the Vermont and Quebec border. ROAC maintains the world's largest "deep hole" granite quarry. The quarry is called the "E. L. Smith Quarry", and the Devonian Barre Granite is mined there. Granite was originally quarried using primitive techniques which implemented hand saws and explosive charges to blast away the "benches" of the quarry. Modern techniques have evolved to