==References==* Blatt, Harvey and Robert J. Tracy, 1996, "Petrology: Igneous, Sedimentary and Metamorphic," 2nd ed., p. 72, Freeman, ISBN 0-7167-2438-3
* Blatt, Harvey and Robert J. Tracy, 1996, "Petrology: Igneous, Sedimentary and Metamorphic," 2nd ed., p. 72, Freeman, ISBN 0-7167-2438-3