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
This Is What Rock n' Roll Looks Like depth about the genre mix in "This Is What Rock n' Roll Looks Like": Although the song's title references the physical appearance of what rock and roll looks like, Porcelain Black revealed in an interview with AOL's "NoiceCreep" that rock and roll is not dependent on the physical appearance of someone. She stated: "This Is What Rock n' Roll Looks Like" received generally mixed reviews by critics, most of whom were surprised with Porcelain Black's outgoing persona and the pop production by RedOne. Gerrick D. Kennedy of "Los Angeles Times" complimented the song's production by stating that it could have