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At least 55 records · Page 3Linked to original sources
USGS1980

Preliminary data describing the distribution of fluoride and silica in the water in the Ogallala aquifer on the High Plains of Texas

The Ogallala aquifer of Texas historically has been known for elevated fluoride concentration, with many areas in excess of 4 milligrams per liter. In addition, on a regional scale, silica concentrations are also somewhat elevated, with concentrations averaging in the 40 to 50 milligrams per liter range. This aquifer provides a unique geochemical and epidemiological study area because it is completely contained within the High Plains physiographic province.

Texas↗
USGS1996

Calcioaravaipaite: A new mineral and associated lead fluoride minerals from the Grand Reef mine, Graham County, Arizona

The Grand Reef mine in southeastern Arizona, best known to collectors for superb crystals of linarite, is also the type locality far a unique suite of lead fluoride minerals. Grandreefite, pseudograndreefite, laurelite, aravaipaite, and artroeite have been found nowhere else; added to this group is calcioaravaipaite, described here for the first time.

Mineralogical Record↗
USGS2015

Corrigendum to “Comparing activated alumina with indigenous laterite and bauxite as potential sorbents for removing fluoride from drinking water in Ghana” [Appl. Geochem. 56 (2015) 50–66]

The authors regret that the application of the t -plot to determine the presence of micropores in the three sorbents needs the following corrections: (1) Fig. 1a, c, e are N 2(g) adsorption and desorption isotherms” (remove “BET”). This correction applies to descriptions in the text as well. (2) Table 2, the column titled “Micropores” is mislabelled, and should be labelled “Film thickness”, which may not equal the pore width. The column titled “Micropore volume” is a correct description for laterite volume 0.0022 cm 3 g −1 ( t = 0.3–0.5 nm), but the other pore volumes listed cannot be identified as corresponding to micropores. They likely comprise both micropores and mesopores in laterite, while the presence of micropores in activated alumina is not clear. The positive y-intercept for the lowest linear portion of the laterite t -plot curve indicates micropores (Fig. 1f), and the shape of the t -plot curve suggests the presence of both micropores and mesopores. The shape of the activated alumina t -plot curve suggests the presence of micropores and mesopores, but the zero intercept for the lowest linear portion of the curve (Fig. 1b) creates uncertainty regarding the presence of micropores. Also see Storck et al., 1998; Hay et al. 2011 and references therein. (Additional note: analytical instrument Micromeritics ® was misspelled as “Micrometrics”). The authors would like to apologise for any inconvenience caused.

Applied Geochemistry↗
USGS1973

Polyphenyl fluorides

Studies related to the chemistry of aromatic fluorine compounds have been carried out at the Illinois State Geological Survey since 1933. In our reference collection we have several compounds that have not previously been described. This communication records data on 18 biphenyl, three terphenyl and some benzene fluorinated derivatives that were obtained as by-products and/or by specific synthesis. ?? 1973.

Journal of Fluorine Chemistry↗
USGS2009

The use of fluoride as a natural tracer in water and the relationship to geological features: Examples from the Animas River Watershed, San Juan Mountains, Silverton, Colorado

Investigations within the Silverton caldera, in southwestern Colorado, used a combination of traditional geological mapping, alteration-assemblage mapping, and aqueous geochemical sampling that showed a relationship between geological and hydrologic features that may be used to better understand the provenance and evolution of the water. Veins containing fluorite, huebnerite, and elevated molybdenum concentrations are temporally and perhaps genetically associated with the emplacement of high-silica rhyolite intrusions. Both the rhyolites and the fluorite-bearing veins produce waters containing elevated concentrations of F - , K and Be. The identification of water samples with elevated F/Cl molar ratios (> 10) has also aided in the location of water draining F-rich sources, even after these waters have been diluted substantially. These unique aqueous geochemical signatures can be used to relate water chemistry to key geological features and mineralized source areas. Two examples that illustrate this relationship are: (1) surface-water samples containing elevated F - concentrations (> 1.8 mg/l) that closely bracket the extent of several small high-silica rhyolite intrusions; and (2) water samples containing elevated concentrations of F - (> 1.8 mg/ l) that spatially relate to mines or areas that contain late-stage fluorite/huebnerite veins. In two additional cases, the existence of high F - concentrations in water can be used to: (1) infer interaction of the water with mine waste derived from systems known to contain the fluorite/huebnerite association; and (2) relate changes in water quality over time at a high elevation mine tunnel to plugging of a lower elevation mine tunnel and the subsequent rise of the water table into mineralized areas containing fluorite/huebnerite veining. Thus, the unique geochemical signature of the water produced from fluorite veins indicates the location of high-silica rhyolites, mines, and mine waste containing the veins. Existence of high F - concentrations along with K and Be in water in combination with other geological evidence may be used to better understand the provenance of the water. ?? 2009 AAG/Geological Society of London.

Colorado↗
USGS1949

The U.S.G.S. phosphate-fluoride-iodate method for the determination of very small amounts of thorium in naturally occurring materials

Detailed procedures are presented for the determination of very small percentages of thorium. The methods are designed to determine 0.001% of thorium oxide as the lower limit and are applicable to nearly all types of rocks. For quantities below a milligram of ThO 2 , the thorium is determined nephelometrically as the iodate or photemetrically with p-dimethylamineasephenylarsonic acid. For quantities of thorium above one milligram of ThO 2 , the thorium is determined gravimetrically. A discussion of the important feature of the methods and a summary of the more important experimental work that lead to the adoption of the procedures.

Report↗