This folder contains correspondence and other documents relating to the procurement, sale, and testing of minerals. Some of the letters pertain to diamonds, which were a crucial component in Edison disc phonograph reproducers and difficult to obtain as a result of the war. Also included is correspondence on the extraction of potash from feldspar, involving Milton Whitney of the U.S. Dept. of Agriculture, the Spar Chemical Co., and patent holder Harry P. Bassett. In addition, there is a confidential memorandum by experimenter Ludwig F. Ott regarding a diamond dust reclamation process, as well as a few unsolicited inquiries regarding diamonds that bear brief notations by Edison. Other correspondents include Robert A. Bachman, general manager of the Edison Storage Battery Co., and Sir Guy R. Gaunt, naval attaché and chief of the British intelligence service in the United States.

Approximately 15 percent of the documents have been selected. The unselected items include correspondence about the transmittal and receipt of samples; analytical reports; and general inquiries, requests, and proposals, some of which were referred elsewhere and many of which are marked "no ans."