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.