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
Forbach Granite (at the time the formation of the stone). Forbach Granite is a bright mica, coloured from gray to pink. Forbach Granite includes the following minerals. Forbach Granite Forbach Granite (), also called Raumünzach-Granite ("Raumünzach-Granit"), is a type of granite rock that occurs in the Northern Black Forest. It is part of the Northern Black Forest's granitic massif, to which Bühlertal granite and Wildbad granite also belong. Forbach granite predominantly outcrops in the counties of Calw and Rastatt. The most important quarrying area for Forbach granite used to be the middle Murg valley near Forbach. Today it is only quarried near