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.

This report gives the results of a study of barite deposits on the adjoining Freeman and Hillsmeier properties in northern Llano County, where a small tonnage of residual barite has been mined or "gophered" during recent years.

The information contained in this circular was gathered by a unit of the WPA State-wide Mineralogical Survey of Texas, a project sponsored by The University of Texas Bureau of Economic Geology.

As an outcome of a paper published by The University of Texas in 1938 calling attention to the high magnesia marbles of the Sharp Mountain area of Llano County, magnesite is mined at the present by two companies, the Meramec Minerals, Inc., and the Texas Mines.