The monazite industry in the United States has been practically at a standstill since 1906, principally for the reason that monazite could be mined and Obtained cheaper from Brazil, where large deposits are found and exploited along the seacoast and in the interior. For merly part of the monazite mined in the States of North and South Carolina was used for the manufacture of thorium nitrate in this country and part of the production was sent to Germany. It seems an Opportune time to call attention to the monazite deposits in the United States, as the imports of thorium nitrate are at present cur tailed. There is reason to believe that a more general manufacture of thorium nitrate may be developed in this country. It may be many years before supplies of the nitrate from Europe can be depended upon. There are deposits of monazite in several of our States, and with the knowledge that a valuable product — mesothorium — can be made as a by — product from the residues of thorium nitrate manufacture the industry may be developed in this country and should pay well. Mesothorium is used successfully in therapy in the same manner as radium. With these facts in view the following description of the occurrences of monazite in the United States, the uses to which its products can be put, and the methods of mining and treatment has been prepared by the Bureau of Mines with the purpose of aiding more efficient utilization of radioactive minerals.