Geology topics

James S. Wahlberg

Publications and source records attributed to James S. Wahlberg.

3 recordsLinked to original sources

USGS1976

Brown, yellow, orange, and greenish-black thorites from the Seerie pegmatite, Colorado

Four types of thorite - brown, yellow, orange, and greenish-black - occur together in narrow fracture fillings rich in brown fluorite near the outer edge of the Seerie pegmatite. The brown thorite is by far the most abundant. The thorites are remarkably similar in composition except for their Fe 2 O 3 and UO 2 contents. The common brown thorite contains about 5 percent Fe 2 O 3 , but the other types have only about 0.3 percent. The greenish-black thorite contains about 15 percent UO 2 ; the yellow and orange, about 7 percent; and the brown, about 3 percent. All four thorites have high total rare-earth oxide contents, which vary from 17.3 to 20 percent. The rare-earth assemblage is unusual in that the heavy rare earths predominate, ytterbium being the most abundant lanthanide. Unheated brown and yellow thorites gave thorite X-ray patterns, but the orange and greenish-black types are metamict. All the thorites gave a ThO 2 -UO 2 X-ray pattern as well as a thorite pattern after heating in air for 1- and 2-hour periods at 1,000°C. In addition, the pattern of the greenish-black thorite contained peaks which we ascribe to a second UO 2 compound. Minute black inclusions present in the greenish-black thorite were identified as uraninite by microprobe analysis.

Colorado↗

USGS1974

Distribution and occurrence of rare earths in the thorium veins on Hall Mountain, Idaho

Rare earths, although equal to or more abundant than thorium in many thorium veins, are much less abundant than thorium in the veins on Hall Mountain, Idaho. Total rare-earth content of these veins ranges from 0.00111 to 0.197 percent in 12 samples from 10 veins; the thoria (ThO 2 ) content, from 0.011 to 5.84 percent. The rare-earth oxide to thoria ratios range from 0.0019 to 3.22. Only two samples contained more rare earths than thorium, and these two samples came from veins related to a fault near the base of a thick sill; the others came from veins near the top of the same sill. The relative amounts of the individual lanthanides are remarkably similar in the Hall Mountain veins, although cerium, gadolinium, or dysprosium are the most abundant in different samples. These veins differ in lanthanide distribution both from the Earth's crust and from the thorium veins of the Lemhi Pass district, Idaho and Montana, in that they contain chiefly yttrium-group rare earths. Most of the rare earths occur in thorite, whose atomic structure will accommodate wide-ranging proportions of the rare earths. Cenosite, one of the few minerals with a high content of the yttrium group of rare earths, was found in one vein.

Idaho↗

USGS1956

Volumetric determination of uranium using titanous sulfate as reductant before oxidimetric titration

A new method for determining uranium in samples containing 0.05 percent or more U 3 O 8 , using titanous sulfate as reducing agent, is much shorter, faster, and has fewer interferences than conventional methods using reductor columns. The sample is dissolved with sulfuric, nitric, perchloric, and hydrofluoric acids. Elements that would otherwise form insoluble fluorides are kept in solution by complexing the fluoride ion with boric acid. A precipitation is made with cupferron to remove interfering elements. The solution is filtered to remove the precipitated cupferrates instead of extracting them with chloroform as is usually done. Filtration is preferred to extraction because any niobium that may be in solution forms an insoluble cupferrate that may be removed by filtering but is very difficult to extract with chloroform. Excess cupferron is destroyed by oxidizing with nitric and perchloric acids, and evaporating to dense fumes of sulfuric acid. The uranium is reduced to U(IV) by the addition of titanous sulfate, with cupric sulfate used as an indicator of the completeness of the reduction. Metallic copper is formed when all the uranium is reduced. The reduced copper is then reoxidized by the addition of mercuric perchlorate, an excess of ferric sulfate added, and the solution titrated immediately with standard ceric sulfate with ferroin as an indicator. Precision of the method compared favorable with methods in common use, both for uranium ores and for most types of uranium-rich materials.

Trace Elements Investigations↗