Salt Lake Tribune | 1914-02-17 | Page 12 | Frisco District is Subject of Report

IfbWIistrict is-subject is-subject of report Beaver County Minirfg Region Investigated by U. S. Geological Survey. In contlnuanco of Its policy of asslntlng in tho development of tho resources In tho metalliferous regions of the country, through nolentiflc Investigations of tlio geologic Btmoturc and tho naturo of the ore bodies, their inodcB of occurrence, and ihclr probable extent, tho United Statefl geological survey haH published a report on the "Geology and Ore Deposits of the San Franclnco mid Adjacent Districts, Dis-tricts, Utah" professional paper SO. Brief preliminary Inspections of these districts were made by the late . i-. Emmons and by Waldomar Lindgren. .tout the detailed study of the rc-Blon ) as been carried out by Geologist B. S. Budr. Mr. Butler's roport, a volume of 212 pages, which embodies results of work tfatrlb-utcd tfatrlb-utcd through throo field scaoons, presonts much general information on the region and may be considored of Mpwjl ; terest becauso It gives a totalled Bfcount. of a part of tho Great basin hitherto only obscurely known Mine workers, consult- and other branches of ecology will find It of especial Interest, both for Its text nnd for the numerous clear-cut and ln-Ptrticture ln-Ptrticture illustrations, which Include half-tones and lino drawings, of geologic structure, mineral associations, alterations altera-tions nnd ore enrichment. The report Is pot so conspicuous for now or radical Ideas as for the presentation presenta-tion of definito evidence throwing now light on existing theories. Jts comparisons compari-sons of the districts discussed with other districts are also especially helpful. Another An-other noteworthy feature is tho description descrip-tion of several minerals, which oro now or unusual or occur in unusual associations, associa-tions, but which are of considerable economic eco-nomic importance in tho San Francisco and adjacent districts. These minerals, Including wurtzltc, anhydrite, plumbo-inrosJte, plumbo-inrosJte, and neaverlto. are adequately described and illustrated, and their origin and significance are discussed. , The section of the report discussing ore deposits 13 of especial value in showing ho relations of the different ' typos of oe to one another and In pointing out i -e limitations, both in oxtent and value, of each type. Tho deposits include cop-, cop-, per ores as replacement veins in quartz mon.onltc and as contact-metamorphlc deposits in limestone, also lead-silver ores, accompanied by a little zlno and copper, aa replacements of certain lime- , Mono beds along fissures and as replacement replace-ment veins In effusive lavas. Transition tvpes between the contact-metamorprlc and silver-lead deposits In limestone aro of especial Interest. Tho discussion of ore gencHls supplies a missing link In the usual chain of evidence by showing the genetic connection between typical monzonlte and ore bodies through transition transi-tion tvpes of aplltlc and pogmatltlc cliar-acter." cliar-acter." The conditions influencing altera- Itlon of the ores in tho different rocks are next considered, with explanations of chemical processes and changes In metal contents, and the discussion is Illustrated by somo verv instructive half-tones showing show-ing minerals in process of alteration. The section closes with some suggestions as to prospecting and a well-balanced consideration of the future of the region, encouraging prospecting and development in some places and discouraging It In others. Another portion of the report is devoted to mine descriptions accompanied by plans and sections which render them especially valuable for study by nil interested in-terested In tho science of oro deposits. .A copy of tho roport may be obtained free on application to tho director of the geological survey, Washington, D, C.