Report issued by the Bureau of Mines over the Leadville Drainage Tunnel. Descriptions and details about the tunnel are presented. This report includes tables, maps, illustrations, and photographs.

Report issued by the U.S. Bureau of Mines on the study of contamination of cores obtained with conventional core barrels. The effect of the oil-based drilling fluid and analysis of the cores are presented. The report includes tables, graphs, and illustrations.

Report issued by the U.S. Bureau of Mines on sub-bituminous slack from Denver, Colorado. The characteristics and properties of 2-1/2 inch slack samples are listed. This report includes tables, graphs, maps, illustrations, and photographs.

From introduction: The Big Boulder prospect is in SE 1/4 sec. 36, T.7N., R.,72W., in Tarimer County, Colorado. The prospect has been opened by four irregular trenches and shallow cuts, and a 10-foot discovery shaft. Hanley 1/4 states that 10.5 tons of beryl were produced from the Big Boulder prospect in 1936, and about 600 pounds in 1941.

From introduction: The results of Geological Survey exploration at Blue Mesa are summarized in this preliminary report. No additional drilling is planned.

A 7118 ft (2170 m) deep geothermal test well was drilled on the south edge of the city of Alamosa, Colorado as part of the Department of Energy's User Coupled Confirmation Drilling Program. The project was selected on the bases of a potential direct heat geothermal resource within the Rio Grande rift graben and resource users in Alamosa. The well site was selected on the hypothesis of a buried horst along which deep thermal fluids might be rising. In addition, there were city wells that were anomalous in temperature and the location was convenient to potential application. The Alamosa No. 1 penetrated 2000 ft (610 m) of fine clastic rocks over 4000 ft (1219 m) of volcaniclastic rock resting on precambrian crystalline rock at a depth of 6370 ft (1942 m). Due to poor hole conditions, geophysical logs were not run. The stabilized bottom hole temperature was 223/sup 0/F (106/sup 0/C) with a gradient of 2.6/sup 0/F/100 ft (47/sup 0/C/km). Limited testing indicated a very low production capacity. 16 refs., 6 figs.

Final report documenting a survey of the Durango quadrangle in Colorado as part of the Platoro Caldera detail survey. This volume outlines survey and analysis methods, and summarizes results.

A fully-parameterized model for the formation and growth of aerosols via gas-to-particle conversion has been developed and tested. A particularly significant contribution is a new method for the prediction of numbers of particles nucleated using information on the vapor source rate, relative humidity, and preexisting aerosol alone, thus eliminating the need to solve a system of coupled ODEs. Preliminary tests indicate substantial reduction in computational costs, but it is recommended that the BIMODAM model be incorporated into a large-scale model of the sulfur cycle in order to more fully test its computational feasibility.

The entry rate of {sup 22}Rn into a basement structure was measured continuously. These measurements demonstrated that radon entry did not vanish even when the structure was slightly pressurized. This persistent entry has been determined to be dominated by diffusion through the floor and walls and a combination of diffusion and convection through the floor-wall joint. The highest indoor radon concentrations occurred during calm periods when the pressure differentials between the inside and outside of the structure were small. The objectives of this work were to identify the origins of the radon and investigate the entry pathways. The radon could originate either in the concrete or in the soil surrounding the structure. Entry pathways into the basement were through the concrete floor and walls as well as through the floor-wall joint. The contributions of the origins and entry pathways were determined by continuously measuring the radon entry rate into the basement, using a trace gas system, and the flux density through portions of the floor and walls. Radon entry through the floor-wall joint could be controlled using a baseboard barrier system. Results indicated that, during calm conditions with wind speeds less than 1 m s{sup {minus}1}, 25 % of the …

The project objective is to explore the generation of soft X-ray laser radiation in a plasma column created by a fast capillary discharge. The proposed capillary lasing scheme offers the potential for compact, simple and efficient soft X-ray laser sources. For this purpose a compact, fast pulse generator which produces 100 kA current pulses with a risetime of 11 ns was constructed. Initial experiments were conducted in evacuated capillaries, in which the plasma is produced by ablation of the capillary walls. The soft X-ray emission from discharges in polyethylene capillary channels was studied to investigate the possibility of amplification in the 3-2 transition of C VI, at {lambda} = 18.2 nm. Time-resolved spectra in which this transition appears anomalously intense with respect to the 4--2 transition of the same ion were obtained. To date, however, this phenomenoa could not be confirmed as gain, as the intensity of the 18.2 nm line has not been observed to increase exponentially as a function of the capillary length. Encouraging results were obtained by fast pulse discharge excitation of capillaries filled with preionized gas. High temperature (Te > 150 eV), small diameter ({approximately}200 {mu}m) plasma columns were efficiently generated. Fast current pulse excitation of …

Rock and stream-sediment samples were collected to define areas favorable for uranium deposits northeast of Gunnison, Colorado. Areas considered most favorable for further exploration are: (1) the Bronco Mountain area, approximately 10 mi south of Taylor Park Reservoir, (2) the area near the Big Red mine, and (3) the area 5 mi north-northeast of Taylor Park Reservoir. On the basis of known deposits in the Marshall Pass and Cochetopa districts, fault contacts between Precambrian granites and Paleozoic or Mesozoic sedimentary rocks are favorable structural sites.

The following report describes the study of sediment in South Park, Colorado, the study taking 464 water samples to test for uranium in the Rocky Mountains.

From introduction: This report details mineral and chemical relations in two uranium-vanadium ores of the Colorado Plateau.

From abstract: Many of the mining districts of the Colorado Front Range mineral belt contain mesothermal sulfide ores that exhibit a zonal distribution. Present data indicate that in most of the zoned districts pitchblende and/or secondary uranium minerals are most abundant in a transition zone between central areas containing predominantly pyritic gold ores and peripheral areas containing dominantly lead-zinc-silver deposits. Copper in the form of chalcopyrite is also probably more abundant in the transition zone than in adjacent zones.

Abstract: "The relative isotopic abundance of copper has been measured in a number of minerals. Suites of samples from Michigan and the Colorado Plateau have been examined to determine if local variations due to isotopic exchange or diffusion could be found. The relative isotopic abundance of copper in specimens from a number of other places was also determined. The variations noted were small but in most cases were felt to be significant because they were larger than the experimental error (0.1 percent in the ratio). A total spread of +3 to -8 parts per mil compared to the standard was found in the specimens tested."

Report discussing uranium oxides, their thermodynamic relations, and how these relations connect to the oxidation states of uranium ores found at the Colorado Plateaus. This report provides information regarding thermodynamic properties of some compounds and ions of the U-O-H2O system, discussion and interpretation of thermodynamic properties, and a summary with conclusion.

A report about the Central City district and adjoining mining areas in the central part of the front range mineral belt which has supplied small quantities of uranium ore intermittently since the discovery of pitchblende at Central City in 1871.

Report discussing the relationship between uranium deposits and hypogene mineral zoning in the Front Range mineral belt of Colorado. This report is mostly based on work done by other geologists.

Report discussing geologic structures which localize carnotite deposits of the Colorado Plateau.

A report about a 22-square mile tract of pre-Cambrain rocks and veins containing thorium mapped at the scale of 1:6,000 located on the west flank of the Wet Mountains, Custer and Fremont Counties, northeast of Westcliffe, Colorado.

The following report analyzes channel samples from two mines (Mineral Joe No. 1 and Virgin No. 3) on the Colorado Plateau that have been studied in detail both mineralogically and chemically.

Report discussing the U.S. Geological Survey's exploration aimed at locating uranium-vanadium deposits of the Beaver Mesa area. The report provides information regarding the geology of the area, uranium-vanadium deposits, the U.S. Geological Survey's exploration, reserves, and plans/recommendations.

Report discussing a study regarding the highly radioactive Tertiary porphyries, which were found in Colorado.

Report discussing the geography and ores of the Spud patch area, which acted as a source of carnotite ore from deposits in a sandstone lens.