Because few other metals can at this time be mined profitably and because the purchasing power of gold has so greatly risen, great interest is being taken in that metal and hundreds of people are seeking deposits of gold are in Arizona. While many of these prospectors are experienced, a large number are "greenhorns" who have no idea how to extract the gold from any are found. This little bulletin has been prepared to answer, in part at least, the large number of inquiries received by the Arizona Bureau of Mines from such people. The Bureau will welcome questions on subjects not covered by this publication, and they will be answered by experts, free of charge, if it is possible to do so without making laboratory tests. For such tests, a charge must be made. No treatment plant of any kind should ever be erected, no matter how small the cost, until the ore to be treated has been completely tested. Thousands of dollars may easily be saved by spending a few hundred dollars on such tests. A successful mining company ever erects a mill until exhaustive tests have been made, and they are just as essential when a small, " rawhide" plant is to be built. 32 p.