1995-03-22_GENERAL DOCUMENTS - M1977451 (4)

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SR-11 (Ike #1 Mine) Designated Mining Operation January 31, 1995 - Page 7 had little, if anything, to do with localization of uranium- vanadium deposits at this horizon. " In fact, his studies found that the mineral composition of all the sandstones exposed from the floor of Summit Canyon up through the mesa cap of Summit Point are "surprisingly similar. " The siltstones and mudstones are mineralogically similar to the sandstones, except that they contain higher proportion of clay minerals. The Brushy Basin mudstones do contain more barite and analcite than the other units because they contain larger amounts of altered rock fragments. The only other exception is that calcite content is about three times higher in ore-bearing sandstones than in non-ore upper Salt Wash sandstones. However, both calcite and silica cement are quite variable in amount and form in unmineralized sandstones. The local variation within the rock types have been described by Shawe (1976) as three rock facies: 1) red-bed facies, 2) carbon facies, and 3) altered facies. The red-bed facies come from diagenetic processes that removed iron from the detrital black opaque minerals by oxidation and redeposited it nearby as hematite coatings and fillings. The carbon facies also formed diagenetically, but under reducing conditions, probably where stagnant water was trapped by thin clay layers in sandstone containing abundant detrital plant fragments. Here, the iron occurs in pyrite instead of hematite. It will oxidize to limonite when exposed to surface or near-surface conditions. The altered facies resulted from solutions introduced following lithification of the sediments. Both red-bed and carbon facies were locally altered. The solutions leached the bulk of the black opaque minerals and destroyed the hematite, thus "bleaching" the rocks. Pyrite was introduced during alteration, as were small amounts of several other trace elements. Shawe mapped most of the upper Salt Wash sandstone and lower Brushy Basin on the west side of Summit Canyon as altered facies. It was during this alteration (which occurred during early Tertiary time) that uranium and vanadium were probably introduced to the sediments, resulting in ore-bodies locally where suitable conditions existed in carbon facies rocks. Several other elements are somewhat enriched in ore, but they are in such small quantities and/or mineral form as to not constitute hazards. The following elements (with their average enrichment ratios in parentheses) may be of interest, but should certainly not be of concern to the State: Co (20) , Ni (20) , Cu (7) , As (17) , Se (6) , Y (8) , Mo (3) , and Pb (9) . Chromium can be highly enriched, but usually in very limited areal extent, in clay minerals near ore bodies. Summary and Conclusions Extensive research has shown that "if uranium and vanadium are oxidized in the same environment, carnotite or tyuyamunite will be precipitated until the uranium or vanadium is used up" (Evans, U. S.G.S. Prof. Paper 320) . Once crystallized, the solubility of