This paper, on the sands of Minnesota, is a report of an investigation begun in 1918, at a time when there was a great demand for information about local molding sands. as a result of the traffic situation that made it difficult or impossible to obtain sands from sources that had previously supplied them. The inquiry, which was in charge of Mr. G. N. Knapp, showed that Minnesota contains an abundance of sands for founding nearly all products. equal to, or better than, the sands that had been imported. Part of the information embodied in the report was placed at the disposal of the metal founders as soon as it became available, either verbally or by means of mimeographed sheets. The field work showed also that molding materials are more widely spread over the state than was supposed. and a fairly comprehensive reconnaissance was made of a considerable part of Minnesota. Materials gathered from widely separated sources were tested in the laboratory and some were tested by founders in their plants. Minnesota contains an abundance of foundry sands and all materials commonly used for making molds in foundries of iron, steel, brass, and aluminum, except possibly a highly plastic refractory clay. An economic bulletin such as this is chiefly utilitarian. It should show the nature of materials used, the tests made to ascertain the value of the materials, and the distribution of the materials in the state. These subjects are taken up separately in this bulletin and the geologic and geographic distribution are discussed in some detail. The report does not contain a geologic map. To have included such a map would have resulted in duplication.