From introduction: The Martha E prospect, in Spring Gulch about three and one-half miles southwest of Idaho Springs, Colo. (fig. 1), is on a claim, originally called the Daisy Freese, which was first prospected by the Stanley Mines. The occurrence of radioactive minerals in the adit was called to the attention of the U. S. Geological Survey in 1950 by the owners of the claim. The Survey's Trace Elements Section Washington Laboratory identified metatorbernite, autunite, and sooty pitchblende.

From abstract: Eight tons of high grade pitchblende ore was sold from the Jo Reynolds mine near Lawson, Clear Creek County, Colo., in 1919. The pitchblende occurs with silver, lead, and zinc in carbonate-quartz veins cutting pre-Cambrian schist, granite gneiss, and granite.

From abstract: Pitchblende is known to occur in the Jo Reynolds deposit, which was primarily a lead-zinc-silver ore body. The reported production in 1919 of 8 tons of high-grade uranium ore, presumably from the lowest workings of the mine, is still unconfirmed but has a fair degree of credibility.

Report discussing the geology and numerous ore deposits of the Chicago Creek area in Clear Creek County, Colorado. Prior to this report, gold, silver, copper, lead, zinc, and uranium were produced from this area.

Report discussing an investigation of radioactivity in part of Clear Creek County, Front Range, Colorado. The methods and results of the reconnaissance are included. Veins containing chalcopyrite were found to be the best source of radioactivity in the region.

Report containing geologic and vein maps for part of the Central City District, Colorado. Tables containing Shafts and adits in the area are included.

Report discussing the results of a geological study of the Idaho Springs-Central City area of the Front Range mineral belt. The study was still in progress at the time of publication.

"The purpose of the reconnaissance was to determine the distribution and the economic importance of the radioactive occurrences of the region. The methods, as well as the results, of the investigation, are given in this report."

A report regarding a geological survey of the geology and ore deposits of the Freeland-Lamartine District, Clear Creek County, Colorado. Concerns work done on behalf of the Division of Raw Materials of the U.S. Atomic Energy Commission.

This report describes the Fall River Area that was examined for favorable areas between known occurrences of pitchblende at Quartz Hill and at Lawson.