RT Journal Article SR Electronic T1 Studies in the mica group JF American Journal of Science JO Am J Sci FD American Journal of Science SP 131 OP 137 DO 10.2475/ajs.s3-34.200.131 VO s3-34 IS 200 A1 Clarke, Frank Wigglesworth YR 1887 UL http://www.ajsonline.org/content/s3-34/200/131.abstract AB