figure 19. Outcrop and samples of the Frontier Formation <strong>in</strong> the southern Spr<strong>in</strong>g Gap area. A, outcrop of green to yellow barren sandstone overla<strong>in</strong> by dark-green to dark-brown radioactive, REE-rich sandstone. B, sample of the upper dark-green to dark-brown REE-rich sandstone (20121128JC-D). C, sample of the green to yellow barren sandstone (20121128JC-E). ppm niobium, and 660 ppm eTh with<strong>in</strong> altered sandstone <strong>in</strong> the Cretaceous Frontier Formation. This sandstone exhibits a m<strong>in</strong>eralogical assemblage typical of beach placer deposits and conta<strong>in</strong>s limonite, pyrite, leucoxene, and an unidentified REE-bear<strong>in</strong>g m<strong>in</strong>eral. The stratigraphy of samples reported by Madsen and Re<strong>in</strong>hart (1982) is ambiguous (K<strong>in</strong>g and Harris, 2002). Recent mapp<strong>in</strong>g (M’Gonigle and Dover, 2004) and field <strong>in</strong>vestigations from this study show that this sandstone is with<strong>in</strong> the lower third of the Frontier Formation (figs. 19 and 20). An exploration trench near the area sampled by Madsen and Re<strong>in</strong>hart (1982), exposes light green to yellow (weathered), angular to subangular, medium- to coarse-gra<strong>in</strong>ed sandstone, with approximately 25 percent weathered plagioclase, 40 percent quartz, 35 percent mafic m<strong>in</strong>erals, 5 percent biotite, and m<strong>in</strong>or limonite and hematite sta<strong>in</strong><strong>in</strong>g (Sample 20121128JC-E). This weathered sandstone unit is overla<strong>in</strong> by a dark green to dark brown, angular, medium- to coarse-gra<strong>in</strong>ed lam<strong>in</strong>ated sandstone (fig. 19) with approximately 40 percent mafic m<strong>in</strong>erals, 25 percent limonite, 20 percent weathered plagioclase, 10 percent quartz, 5 percent black opaque m<strong>in</strong>erals, and calcite fracture fills (Sample 20121128JC- D). In places, the mafic m<strong>in</strong>erals <strong>in</strong> the upper portion of the exposure appear to have grown around plagioclase. Background radioactivity <strong>in</strong> the area is 90 cpm and the upper mafic-rich unit exhibits up to three times the background 260 cpm; the lower unit exhibits no anomalous radioactivity. The bedd<strong>in</strong>g here strikes 202˚ and dips 55˚ NW. The lower, light green sandstone (Sample 20121128JC-E) is not significantly enriched <strong>in</strong> any of the REE. However, the upper, dark green to dark brown sandstone (Sample 20121128JC-D) is enriched <strong>in</strong> all of the REE as well as scandium, yttrium, and niobium; only europium, lutetium, and scandium are enriched at less than five times crustal abundances (table 17). Frontier Formation, Spr<strong>in</strong>g Gap, NE¼SW¼ sec. 8, T. 16 N., R. 117 W., U<strong>in</strong>ta County The same altered Frontier Sandstone as that was sampled <strong>in</strong> sec. 30 crops out here and is reported by Madsen and Re<strong>in</strong>hart (1982) to conta<strong>in</strong> 650 ppm lanthanum, 50 ppm yttrium, 120 ppm niobium, 600 ppm eTh, 25 ppm eU, and an elemental assemblage typical of beach placer deposits. The sandstone exposed <strong>in</strong> a prospect pit at this locality is similar to that of sample 20121128JC-D. It is dark green to dark brown, angular, and medium- to very coarse-gra<strong>in</strong>ed, with approximately 40 percent mafic m<strong>in</strong>erals, 20 percent limonite, 20 percent weathered plagioclase, 10 percent quartz, 2.5 percent black opaque m<strong>in</strong>erals, 2.5 percent hematite, 52
figure 20. Sample locations and geology of the Spr<strong>in</strong>g Gap area, U<strong>in</strong>ta County, modified from M’Gonigle and Dover (2004). 53
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are earth elements in Wyoming Wayne
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Rare Earth Elements in Wyoming Wyom
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Deacon’s Prayer Group Claims . .
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- Page 17 and 18: Gosen, Foley, and Cordier, 2010). T
- Page 19 and 20: Extraction of rEE Aside from genera
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- Page 23 and 24: REE deposit in Wyoming and is curre
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- Page 29 and 30: Precambrian occurrences Precambrian
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- Page 39 and 40: lbs) for 1957 and 450 kg (1,000 lbs
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- Page 45 and 46: table 10. Concentration of the REE,
- Page 47 and 48: tertiary-aged Igneous occurrences L
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- Page 51 and 52: 43 figure 15. Locations of 1952 USB
- Page 53 and 54: samples 20110824WS-C and 20110824WS
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- Page 57 and 58: tourmaline, amphibole, spinel, sphe
- Page 59: Mud creek, nW¼nE¼ sec. 19, t. 44
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- Page 67 and 68: figure 22. Sample locations and lit
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- Page 85 and 86: f fergusonite 12, 13, 33 Ferris Mou
- Page 87 and 88: monazite 1, 11, 12, 13, 14, 15, 18,
- Page 89 and 90: strontianite 18, 19 Stump Formation
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