The ore deposits of Utah . said to have beenfound in the ore horizon, but none wasseen in the Eldorado workings. The ore occurs in irregular bunchesalong the dolomite bed, and in the largest work-ings on the Eldorado property has been followedfor about 100 feet north along the strike andan equal distance down the eastward dip. Theassay records following show the variation incomposition of the ore. The first two of these represent bunches of ore with galena greatly predominating; the third a nearly pure mixture of pyrite and quartz; the fourth a segregation of zinc blende. 35416°—19 15 Assays o
The ore deposits of Utah . said to have beenfound in the ore horizon, but none wasseen in the Eldorado workings. The ore occurs in irregular bunchesalong the dolomite bed, and in the largest work-ings on the Eldorado property has been followedfor about 100 feet north along the strike andan equal distance down the eastward dip. Theassay records following show the variation incomposition of the ore. The first two of these represent bunches of ore with galena greatly predominating; the third a nearly pure mixture of pyrite and quartz; the fourth a segregation of zinc blende. 35416°—19 15 Assays of ore from the Eldorado mine, Sierra Madre district. Gold. Silver. Lead. Copper. Insol-uble. Zinc. Sul-phur. Iron. Oz. Trace. 5G. 0 Trace. None. Trace. None. Trace. None. Trace. None. None. (a) («) a Not determined. Samples of minerahzed rock intervening be-tween ore bunches range in content from a. FiGUKE 39.—Section showing relations between deposits in dolomiteand granite, Sierra Madre district. trace to an ounce of silver to the ton and from4 to 5 per cent each of lead and zinc. Thesuccess of working this deposit depends largelyon the careful separation of the lead and zincores and in the ehmination of gangue matterfrom material shipped. CONCLUSIONS. The character of the mineralization, both inthe granite and in the dolomite, point to theaction of weak solutions remote from their 226 ORE DEPOSITS OF UTAH. source. The failure of ore and gangue min-erals to replace the plagioclaso of the granitemore extensivel}- and their practically com-plete inability to replace the microchne indi-cate lack of concentration and scarcity ofstrong minerahzing elements like-fluorine andcarbon dioxide. The small amounts of sec-ondary sericite, quartz, dolomite, and calcitein the mincraUzod zones of the granite may beregarded as merely recrystaUized and more orless tran
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectminesandmineralresou
