From abstract: This report describes the geology and mineral resources of the Bayhorse quadrangle, much of the Custer quadrangle, and the area surrounding Round Valley, all in Custer County, and a small part of the Sawtooth quadrangle in Blaine and Custer Counties, Idaho.

From introduction: This report describes the deposits of analcite in the Green River formation, to compare them with other similar deposits, and to present them with other similar deposits, and to present the observations and inferences that led him to explain them as alteration products of volcanic ash that fell into an ancient saline lake. The report also records the occurrence of several thin beds of sepiolite, or meerschaum, in the Green River formation and presents new data on the molds of saline minerals of the Green River formation whose determination affects directly the interpretation of the analcite and sepiolite deposits.