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 Mountain (Texas) as Enchanted Rock State Natural Area can be seen in its undisturbed state west of Marble Falls near Fredericksburg, Texas. Granite Mountain (Texas) Granite Mountain is a solid dome, also known as a bornhardt, of pink granite (pink granite is also known as Sunset Red) rising over 860 feet one mile west of Marble Falls, Texas. Since quarry operations began in the late 19th century, the distinctive pink-red colored rock has been used in the construction of the Texas State Capitol in Austin, Texas, and also for the construction of the Galveston Seawall. The mountain no longer looks like a