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J. A. Erdman

Publications and source records attributed to J. A. Erdman.

32 records · Page 2Linked to original sources
USGS1985

The use of plants in prospecting for gold: A brief overview with a selected bibliography and topic index

The focal point of this report is a bibliography of 133 references and an associated topic index — both of which could be useful to geochemists attempting to locate new Au deposits. Fifty of these references originated in the Soviet Union, where most of the initial work on biogeochemical exploration for Au had been done. The 15 topics in the index range from agriculture (Au in crop plants) to silver. As an introduction to the bibliography, we have briefly described some examples of applications and difficulties in using plants. These examples are drawn from the literature and from field experience. Because of the generally low Au concentrations found in plants, the analysis of plant tissue is critical to the successful application of the biogeochemical method of prospecting. Neuron activation analysis is the most widely used method to detect Au in plants, due largely to its sensitivity; levels in the parts per billion range are easily attained. Two general types of sampling media are used in prospecting for Au: humus and living plants. Humus has been widely used in Canada, but the sampling of plants has increased there and elsewhere in recent years. Our use of douglas-fir ( Pseudotsuga menziesii ) at a Au-bearing stockwork in Idaho is a prime example. A maximum Au concentration of 14 μg/g (ppm) was detected in the wood ash of this coniferous tree, well above the normal concentration of ≈ 0.15 μg/g. Among shrubs that might be useful in Au prospecting, we recommend sagebrush or wormwood (genus Artemisia ), because it is extremely responsive to concealed mineralization. It has been used extensively in the Soviet Union and could be used in areas of the western United States where disseminated Au occurrences might be located.

Journal of Geochemical Exploration↗
USGS1984

Copper and cobalt in aquatic mosses and stream sediments from the Idaho Cobalt Belt

Samples of stream sediments and aquatic mosses were collected from nine sites across several mineralized zones at the southeasternmost extension of the Idaho Cobalt Belt. Because the steepness of the terrain and the attendant high flow rate of the streams made it difficult to obtain adequate sediment samples, mosses were considered as an alternative sampling medium. The results not only showed that the Cu and Co content of the mosses correlated almost perfectly with that of the sediments, but that the contrast between samples taken from mineralized and background areas was greater in mosses, especially for Co. Maximum concentrations of 35,000 μg/g Cu and 2000 μg/g Co were observed in the ash of mosses, compared to maximum concentrations of 1700 μg/g and 320 μg/g, respectively, in the associated sediments. Species identification was considered unimportant, which should dispel some reluctance to use mosses in mineral exploration.

Journal of Geochemical Exploration↗
USGS1982

Uranium in spring water and bryophytes at basin creek in central idaho

Arkosic sandstones and conglomerates of Tertiary age beneath the Challis Volcanics of Eocene age at Basin Creek, 10 km northeast of Stanley, Idaho, contain uranium-bearing vitrainized carbon fragments. The economic potential of these sandstones and conglomerates is currently being assessed. Springs abound at the contacts of rock units, and water from these springs supports abundant growths of bryophytes (mosses and liverworts). Water from 22 springs and associated bryophytes were sampled; two springs were found to contain apparently anomalous concentrations (normalized) of uranium — as much as 6.5 μg/L (ppb) in water and 1800 μg/g (ppm) in ash of mosses. Moss samples from both springs also contained anomalous concentrations of arsenic, and one contained highly anomalous amounts of beryllium. Water from a third spring contained slightly anomalous amounts of uranium, and two species of mosses at the spring contained anomalous uranium (400 and 700 μg/g) and high levels of both cadmium and lead. Water from a fourth spring was normal for uranium (0.18 μg/L), but the moss from the water contained a moderate uranium level and highly anomalous concentrations of lead, germanium, and thallium. These results suggest that, in the Basin Creek area, moss sampling at springs may give a more reliable indication of uranium occurrence than would water sampling. The reason for this may be the ability of mosses to concentrate uranium and its associated pathfinder elements and to integrate uranium fluctuations that occur in the spring water over any period of time.

Idaho↗
USGS1981

Laser fluorometric analysis of plants for uranium exploration

A preliminary test of biogeochemical exploration for locating uranium occurrences in the Marfa Basin, Texas, was conducted in 1978. Only 6 of 74 plant samples (mostly catclaw mimosa, Mimosa biuncifera ) contained uranium in amounts above the detection limit (0.4 ppm in the ash) of the conventional fluorometric method. The samples were then analyzed using a Scintrex UA-3 uranium analyzer ∗ - an instrument designed for direct analysis of uranium in water, and which can be conveniently used in a mobile field laboratory. The detection limit for uranium in plant ash (0.05 ppm) by this method is almost an order of magnitude lower than with the fluorometric conventional method. Only 1 of the 74 samples contained uranium below the detection limit of the new method. Accuracy and precision were determined to be satisfactory. Samples of plants growing on mineralized soils and nonmineralized soils show a 15-fold difference in uranium content; whereas the soils themselves (analyzed by delayed neutron activation analysis) show only a 4-fold difference. The method involves acid digestion of ashed tissue, extraction of uranium into ethyl acetate, destruction of the ethyl acetate, dissolution of the residue in 0.005% nitric acid, and measurement.

Texas↗
USGS1981

Uranium in big sagebrush from western U.S. and evidence of possible mineralization in the Owyhee mountains of Idaho

Two regional studies of big sagebrush ( Artemisia tridentata ), a widely distributed and dominant shrub in the western United States, have shown its responsiveness to known uranium mineralization in the Monument Hill and Pumpkin Buttes districts of the southern Powder River Basin, Wyoming, and the Uravan mineral belt area in southeastern Utah and southwestern Colorado. Uranium concentrations in the ash of 154 stem-and-leaf samples of sagebrush are plotted on two maps, one representing the sampling design for the Powder River Basin study, and the other representing the sampling design for the Colorado Plateaus, the Basin and Range, and the Columbia Plateaus physiographic provinces of the West. Sites having high concentrations in sagebrush correspond not only to the above uranium districts, but also reveal an area along the northeast flanks of the Owyhee Mountains in Idaho that should be further explored for its possible uranium potential.

Journal of Geochemical Exploration↗