. The ore deposits of Utah. r andother nodules that are composed largely ofiron oxide cementing quartz and strongly sug-gesting altered pyrite. Massive beds of sand-stone inclosed in these shoots are said tobe commonly too low in silver content to beof commercial value. Rolker ^ gives the following description ofthe reefs: The reefs themselves are made up of whitish-gray andred to reddish-brown sandstones, and between the reefslie beds of clay shale, varying in color from blue to greento cinnamon brown. The ore occurs in similar strata of 1 Op. cit., pp. 24-26. SILVER RKEF DTSTRTOT. 589 sandst
. The ore deposits of Utah. r andother nodules that are composed largely ofiron oxide cementing quartz and strongly sug-gesting altered pyrite. Massive beds of sand-stone inclosed in these shoots are said tobe commonly too low in silver content to beof commercial value. Rolker ^ gives the following description ofthe reefs: The reefs themselves are made up of whitish-gray andred to reddish-brown sandstones, and between the reefslie beds of clay shale, varying in color from blue to greento cinnamon brown. The ore occurs in similar strata of 1 Op. cit., pp. 24-26. SILVER RKEF DTSTRTOT. 589 sandstone and clay shale. The roof is generally markedby a reddish micaceous sandstone, while the floor is madeup of an arenaceous sandstone of a whitish color, withargillaceous sands underlying. The outcrop of the ore less frequently vegetable remains than the remainingportion and the White Reef, and in parts these remainsare absent. In other parts, and thia true for thewhole district, we find the producing sandstone beds. 50 100 150 200 Feet Figure 70.—Vertical cross section of LastChancemine. is marked on the east face of the reef, with the excep-tion of those places where the former apex of the reef hasbeen washed off. as in portions of the Buckeye Reef onits northwest side of the horseshoe. The ore is by nomeans confined always to one bed, but it is limited to asilver zone of from 30 to 90 feet wide, horizontally meas-ured, and anywhere within this belt the horn silver isliable to be found. As a rule it is more concentrated incertain layers (beds) of this belt, but in places it is soscattered as to bring the grade down to a uniform $10,which at present does not pay to work. Frequently, also,the ore is thrown in consequence of very fine slips fromone bed into another. Hence the giving out of the orein one bed is not exactly a discouraging fact, for a cross-cut may, and very often does, prove it to have jumpedinto a lower or higher bed, respectively. In other words,the ar
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectminesandmineralresou
