RT Journal Article SR Electronic T1 Communications from the U. S. Geological Survey, Rocky Mountain Division; on hypersthene andesite JF American Journal of Science JO Am J Sci FD American Journal of Science SP 139 OP 144 DO 10.2475/ajs.s3-25.146.139 VO s3-25 IS 146 A1 Cross, W. YR 1883 UL http://www.ajsonline.org/content/s3-25/146/139.abstract AB