Thermodynamic investigation of uranyl vanadate minerals: Implications for structural stability

Spano, Tyler L.; Dzik, Ewa A.; Sharifironizi, Melika; Dustin, Megan K.; Turner, Madison; Burns, Peter C.

doi:10.2138/am-2017-5894

Cited by 18 publications

(13 citation statements)

References 29 publications

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“…The sheet (Fig. 5b), comprised of a mosaic of pairs of edgesharing UO 7 bipyramids and edge-sharing VO 4 pyramids, is of the well-known francevillite topology (Burns 2005;Lussier et al 2016;Spano et al 2017). Sheets are stacked parallel to {101}.…”

Section: Description Of the Crystal Structurementioning

confidence: 99%

“…Uranyl-vanadate minerals are relatively insoluble over a range of pH conditions (circumneutral and alkaline) and they are quite abundant in Colorado Plateau-type U-V deposits, as well as in the mine and mill tailings (Evans and Garrels 1958;Dahlkamp 1993;Spano et al 2017;Kampf et al 2019). The most well-known and abundant of these is carnotite, K 2 (UO 2 ) 2 (V 2 O 8 )•nH 2 O (where n is usually given in the range 1-3).…”

Section: Introductionmentioning

confidence: 99%

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Vandermeerscheite, a new uranyl vanadate related to carnotite, from Eifel, Germany

Plášil¹,

Kampf²,

Škoda³

et al. 2019

J. Geosci.

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Vandermeerscheite (IMA2017-104), K 2 [(UO 2) 2 V 2 O 8 ]•2H 2 O, is a new uranyl-vanadate mineral from the Schellkopf quarry, Eifel, Germany. The new mineral occurs in cavities of volcanic rocks, mostly growing on phillipsite-K. It forms rosettelike aggregates of thin blades up to 50 µm long. Crystals are flattened on {101}, and elongated on [101], with crystal forms {010}, {101} and {111}; crystals are transparent with a vitreous luster. Vandermeerscheite is non-fluorescent under both long-and short-wavelength ultraviolet radiation. The Mohs hardness is ~2. The calculated density is 4.502 g•cm-3 based on the empirical formula; 4.507 g•cm-3 for the ideal formula. Vandermeerscheite dissolves easily in dilute HCl at room temperature. The new mineral is biaxial (-), with α = 1.83 (calc.), β = 1.90(1), γ = 1.91(1) (measured in white light at 22 °C). The measured 2V is 40(10)° estimated from conoscopic observation of interference figure; dispersion is moderate r < v. No pleochroism was observed. Optical orientation is X ≈ ⊥ {101}, Y ≈ [101], Z = b. The empirical formula of vandermeerscheite (on the basis of 14 O apfu) is (K 1.87 Ca 0.05 Na 0.04) Σ1.96 [(U 1.005 O 2) 2 V 1.99 O 8 ]•2H 2 O. Raman spectrum is dominated by the vibrations of UO 2 2+ and V 2 O 8 units. Vandermeerscheite is monoclinic, P2 1 /n, a = 8.292(2),

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Section: Description Of the Crystal Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vandermeerscheite, a new uranyl vanadate related to carnotite, from Eifel, Germany

Plášil¹,

Kampf²,

Škoda³

et al. 2019

J. Geosci.

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“…9, 11–18 Uranium and V can also be present in solid form as oxide, phosphate, carbonate, vanadate, and silicate mineral phases. 19–22 For instance, their co-occurrence as carnotite [K 2 (UO 2 ) 2 V 2 O 8 ], tyuyamunite [Ca(UO 2 ) 2 V 2 O 8 ·(5–8)H 2 O], metahewettite [CaV 6 O 16 ·3(H 2 O)], melanovanadite [CaV 4 O 10 ·5(H 2 O)], and V-bearing clays has been observed at the Rough Rock Sandstone of the Cretaceous Mesa Verde Group study region located in southwestern US. 23 Uranium oxides such as schoepite [(UO 2 ) 8 O 2 (OH) 12 ·12(H 2 O)] are commonly occurring minerals that also influence uranyl solubility under oxic and suboxic environments between pH 6–9.…”

Section: Introductionmentioning

confidence: 99%

Reactive Transport of U and V from Abandoned Uranium Mine Wastes

Avasarala¹,

Lichtner

Ali³

et al. 2017

Environ. Sci. Technol.

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The reactive transport of uranium (U) and vanadium(V) from abandoned mine wastes collected from the Blue Gap/Tachee Claim-28 mine site in Arizona was investigated by integrating flow-through column experiments with reactive transport modeling, and electron microscopy. The mine wastes were sequentially reacted in flow-through columns at pH 7.9 (10 mM HCO3−) and pH 3.4 (10 mM CH3COOH) to evaluate the effect of environmentally relevant conditions encountered at Blue Gap/Tachee on the release of U and V. The reaction rate constants (km) for the dissolution of uranyl–vanadate (U–V) minerals predominant at Blue Gap/Tachee were obtained from simulations with the reactive transport software, PFLOTRAN. The estimated reaction rate constants were within 1 order of magnitude for pH 7.9 (km = 4.8 × 10−13 mol cm−2 s−1) and pH 3.4 (km = 3.2 × 10−13 mol cm−2 s−1). However, the estimated equilibrium constants (Keq) for U–V bearing minerals were more than 6 orders of magnitude different for reaction at circumneutral pH (Keq = 10−38.65) compared to acidic pH (Keq = 10−44.81). These results coupled with electron microscopy data suggest that the release of U and V is affected by water pH and the crystalline structure of U–V bearing minerals. The findings from this investigation have important implications for risk exposure assessment, remediation, and resource recovery of U and V in locations where U–V-bearing minerals are abundant.

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“…Among these, carnotite and tyuyamunite can be used to define the pH conditions of formation in the outer part of the weathered zone. Although historically it had been considered that these minerals typically crystallized under alkaline conditions and only very rarely at pH < 6 [77,78] -unless rauvite was present [95]-, recent studies have shown that they can easily form under slightly acidic environments (pH = 5.5-7) [94,96,97]. A shift towards slightly acidic conditions in Eureka is consistent with mineralizing fluids affected by extensive sulphide alteration.…”

Section: Stage 5: Supergene Mineralisationmentioning

confidence: 76%

Sandstone-Hosted Uranium Deposits as a Possible Source for Critical Elements: The Eureka Mine Case, Castell-Estaó, Catalonia

et al. 2019

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The Eureka deposit in Castell-estaó in the Catalan Pyrenees is a Cu–U–V deposit, hosted by Triassic red-bed sandstones, and classified here as a low-temperature, sandstone-hosted stratabound metamorphite U deposit. The main mineralisation is stratabound, related to coal-bearing units and produced during the Alpine deformation by migration of hydrothermal fluids. In this stage, the original sedimentary and diagenetic components (quartz and calcite, micas, hematite and locally apatite) were replaced by a complex sequence of roscoelite, fine-grained REE phosphates, sulphides and Ni–Co arsenides and sulpharsenides, Ag–Pb selenides, bismuth phases, sulphosalts and uraninite. The black shales of the Silurian sediments underlying the deposit and the nearby Carboniferous volcanoclastic rocks are interpreted as the source of the redox-sensitive elements concentrated in Eureka. The sulphur source is related to leaching of the evaporitic Keuper facies. The REE transport would be facilitated by SO4-rich solutions. The reduction of these solutions by interaction with organic matter resulted in the widespread precipitation of REE and redox-sensitive elements, including many critical metals (V, Bi, Sb, Co), whereas barite precipitated in the oxidized domains. The occurrence of similar enrichments in critical elements can be expected in other similar large uranium deposits, which could be a source of these elements as by-products.

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Thermodynamic investigation of uranyl vanadate minerals: Implications for structural stability

Cited by 18 publications

References 29 publications

Vandermeerscheite, a new uranyl vanadate related to carnotite, from Eifel, Germany

Vandermeerscheite, a new uranyl vanadate related to carnotite, from Eifel, Germany

Reactive Transport of U and V from Abandoned Uranium Mine Wastes

Sandstone-Hosted Uranium Deposits as a Possible Source for Critical Elements: The Eureka Mine Case, Castell-Estaó, Catalonia

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