A geologic map and a bulletin describing the geology and mineral deposits of Gillespie County, Texas, are being prepared by the Bureau of Economic Geology. Awaiting completion of this map and bulletin, abbreviated mimeographed circulars describing the more important mineral deposits are being issued by the Bureau. The first scheelite recognized in Gillespie County was mentioned in a recent circular. Work Project No.

This report deals essentially with the occurrence of manganese on the Ingram-Howe ranch, 3 miles north of Shumla, where several test pits were dug and the manganese sampled for analyses. Included also are brief descriptions of the occurrence of manganese on the Babb and Mills ranches along the Pecos River. The purpose of this investigation was to locate manganese deposits, determine their mode of occurrence, tonnage, and whether or not the deposits could be mined on a commercial basis.

Feldspars represent one of the most abundant groups of minerals and account for approximately 60 percent of the igneous rocks of the earth, according to Clark. All are grouped in a series of related aluminum silicates that contain varying amounts or proportions of potash, soda, and lime. The three principal types are: potash feldspars (microcline and orthoclase); soda feldspar or albite; and soda-lime feldspars (plagioclase).

Young County, located in the belt of Pennsylvanian and Permian formations of north-central Texas, is one of the important oil-bearing counties in the State. In 1930, a geologic map of the county was issued by the Bureau of Economic Geology of The University of Texas in cooperation with the American Association of Petroleum Geologists. In the southern part of the county, the formations were mapped at that time in considerable detail, but in the northern part, where the formations are difficult to follow owing to changes in facies, the mapping is less satisfactory.