Geology topics
Publications and source records attributed to Hubert William Lakin.
All of the data are tabulated here (Table 1-43) that we have received through August, 1977 on the six reference samples that were sent to 247 laboratories. Data were received from 109 laboratories. The data are tabulated by method of analysis and by element.
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A sensitive method for the determination of less than crustal abundance amounts of selenium has been developed that can be useful in the geochemical investigation of selenium. The sample is roasted with a flux of sodium carbonate, chloride, and chlorate and then digested in a mixture of nitric and phosphoric acids. The resulting solution is stabilised; the selenium is reacted with 2,3-diaminonaphthalene to form 4,5-benzopiazselenol, extracted with cyclohexane, and measured fluorometrically. The lower limit of selenium content of a sample that can be determined by this method is 0.04 p/m using a 0.5-g sample.
A laboratory method for the determination of gold in large (100-gram) samples has been developed for use in the study of the gold content of placer deposits and of trace amounts of gold in other geologic materials. In this method the sample is digested with bromine and ethyl ether, the gold is extracted into methyl isobutyl ketone, and the determination is made by atomicabsorption spectrophotometry. The lower limit of detection is 0.005 part per million in the sample. The few data obtained so far by this method agree favorably with those obtained by assay and by other atomic-absorption methods. About 25 determinations can be made per man-day.
The field methods described in this report are those currently used in geochemical prospecting by the U. S. Geological Survey. Some have been published, others are being processed for publication, while others are still being investigated. The purpose in compiling these methods is to make them readily available in convenient form. The methods have not been thoroughly tested and none is wholly satisfactory. Research is being continued.
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The zinc content of thirty different kinds of plants growing on slime ponds containing on the average 12.5 per cent zinc were determined by the dithizone method. The zinc content ranged from 39 p.p.m. in the fruit of the false solomon's seal (Smilacina racemosa) to 5,400 in the horsetail (Equiseteum arvense}. This latter plant varied considerably in zinc at different places on the slime ponds. The zinc contents of the aspen (Populus grandidentata}, ragweed {Ambrosia artemisiifolia), and horsetail grown on normal soils are compared to those on the slime ponds and it is recommended that the poplar and ragweed be studied further as indicators of zinc ore bodies.