RT Journal Article SR Electronic T1 On some general terms applied to metamorphism, and to the porphyritic structure of rocks JF American Journal of Science JO Am J Sci FD American Journal of Science SP 69 OP 72 DO 10.2475/ajs.s3-32.187.69 VO s3-32 IS 187 A1 James Dwight Dana YR 1886 UL http://www.ajsonline.org/content/s3-32/187/69.abstract AB