Vanadium Chlorite from a Sandstone-Hosted Vanadium-Uranium Deposit, Henry Basin, Utah

Abstract

Abstract--An unusual vanadium chlorite precipitated during the formation of a vanadium-uranium ore deposit in the Henry Basin, southeastern Utah. The ore deposit formed by reduction and precipitation of U and V in the presence of organic matter at the interface between a stagnant brine and overlying, circulating meteoric water. Some samples of the vanadium chlorite (heated before analysis) contain > 10% V20~. In fresh samples, most of the vanadium is in the trivalent oxidation state. X-ray powder diffraction data suggest that Fe and V are concentrated preferentially in the interlayer hydroxide sheets of the chlorite. A d(060) value of 1.52 ,~ indicates that the chlorite probably has a dioctahedral structure which is distended by the presence of octahedral Fe and V. The vanadium ore zone is flanked by peripheral zones containing perfectly ordered chlorite/smectite. This chlorite/smectite contains much less V than the pure chlorite. This chlorite may have formed by the progressive precipitation of vanadium-rich interlayer hydroxide sheets in the mixed-layer chlorite/smectite in the most reducing portion of the ore zone. The pure chlorite is a 11b polytype, which, for nonvanadiferous analogs, is ordinarily found in high-temperature environments; however, no evidence exists to show that these rocks have ever been exposed to elevated temperatures. In fact, the presence of unreacted smectite in a potassium-rich setting and the low vi~rinite reflectance of coalified plant debris indicate a low-temperature history for these sediments.

Polygenic chamosite from a hydrothermalized oolitic ironstone (Saint-Aubin-des-Châteaux, Armorican Massif, France): crystal chemistry, visible–near-infrared spectroscopy (red variety) and geochemical significance

“…Thus, the presence of V in chamosite appears to be a necessary but not sufficient condition for the formation of the red variety. This is confirmed by Whitney & Northrop (1986), who have described a V-rich chlorite of (normal) green colour, where V (mainly trivalent) is concentrated in the octahedral sites of the brucite-type sheet. In similar samples, Meunier (1994) considers only V 3+ , which substitutes Al in octahedral sheets.…”

“…In order to check this model of Fe/V IVCT, it would be useful to perform Vis–NIR spectroscopic studies on other vanadiferous green chlorites, such as those from Utah (Whitney & Northrop, 1986). According to the proposed model, such a green colour may be due either to the association of two absorption bands at 550 and 700 nm (Fe 2+ /V 4+ and Fe 2+ /Fe 3+ IVCT, respectively) or to the lack thereof (only Fe 2+ and V 3+ ).…”

Generalized relationships between the ionic radii of octahedral cations and the b crystallographic parameter of clays and related minerals

“…The clinochlore and cookeite samples with refined single crystals fall on or close to the correlation line. The uncommon vanadium-rich chlorites (Whitney & Northrop, 1986), assuming Fe and V as trivalent cations, as well as Fe 3+ -sudoites (Billault et al, 2002), do not reveal any specific behaviour (Fig. 21a).…”

“…To avoid any potential bias from using a unique data source and to enlarge the range of chemical compositions investigated for chlorite, the compiled data from Radoslovich (1962) were added, as well as a few other samples (i.e. two samples whose single-crystal structure has been refined: one ordered triclinic clinochlore (Smyth et al, 1997) and one cookeite (Zheng & Bailey, 1997b); and four uncommon chlorites, namely V 3+ -rich chlorites (Whitney & Northrop, 1986) and Fe 3+ -sudoites (Billault et al, 2002; Table 8).…”