From Introduction: "Figure 1 shows the location of sources that have been either exploited or seriously considered at one time or another, super-imposed upon a map indicating by small letters the order of consumption of K2O in the leading States; the amount used in these States, together with the percentage of the total consumption of potash used as fertilizer in the United States in 1939, is given in table 1. Figure 2 shows the domestic production and total consumption of potassium salts, in terms of tons of K2O, with the value per unit at the plants, for each year since 1913. Considered together, these two figures tell a significant story."

From Abstract: "The micaceous schist ores yielded concentrates containing 95 to 98 percent mica, with recoveries ranging from 70 to 83 percent. Part 1 of this report summarizes the process development work and demonstrates the feasibility of producing commercial-grade mica concentrates. The report also includes details of commercial beneficiation and grinding of mica. Also included in part 2 of this report are details of commercial mica production, including methods of mining, recovering, and grinding mica, and information on the production, uses, and prices of mica."

From Introduction: "The investigation described in this report was carried on to determine the practicability of applying technical control of clay disperse systems to the refining of kaolins and the utilization of the prepared clay in the manufacture of vitreous china and wall tile."

Report issued by the U.S. Bureau of Mines on exploration of kaolin clay deposits for alumina. Properties of the kaolin clay and alumina recovered are listed. This report includes tables, graphs, and illustrations.