RT Journal Article SR Electronic T1 Piedmontite and scheelite from the ancient rhyolite of South Mountain, Pennsylvania JF American Journal of Science JO Am J Sci FD American Journal of Science SP 50 OP 57 DO 10.2475/ajs.s3-46.271.50 VO s3-46 IS 271 A1 George Huntington Williams YR 1893 UL http://www.ajsonline.org/content/s3-46/271/50.abstract AB