In the past decade, military and economic pressures have greatly accelerated research in the field of physical metallurgy. As a result, many uses have been found for elements which hitherto were considered laboratory curiosities, and now some of these minor metals are of strategic importance. This newly-created demand has prompted the extractive metallurgist to devise methods of recovering these elements and to determine which raw materials are the best sources. In some cases the prospector finds deposits which, because of size or some other favorable factors, may encourage the chemist and metallurgist to work out new recovery and refining methods, although the usual role of the prospector is to search for deposits of material already in demand. In any event, the prospector should know what substances to seek, some of the important characteristics of those substances, how they occur geologically, and what tests can be used to determine their presence. The lack of uses developed for the strategic minor metals until recently is a direct reflection of the rarity of known important deposits of these metals. If relatively large, rich deposits of them had been known in the past, there is little doubt that the metals would long since have been put to use. Another factor which delayed the utilization of the strategic minor metals is the difficulty with which many of them are separated from their impurities. The difficulty of separation gives rise to another problem as far as the prospector is concerned; that is, the identification or testing for these metals. With the exception of two or three of them, there are no satisfactory field tests that can be used. Most of the strategic minor metals occur in very minor concentrations and bear marked chemical similarity to other, more abundant elements; hence their detection by chemical methods necessarily involves the use of elaborate, time-consuming and expensive laboratory procedures.