This article surveys the geographical distribution of metal ores, grouped into six categories: iron, manganese, chromium, silver-lead-zinc, copper and tin. The author reviews the occurrence of these ores throughout the world, and their association primarily with broad geotectonic zones. The essential information is encompassed in six maps. Legends explain the classification of the deposits by age (metallogenic eras), type and paragenetic associations of minerals. The symbols for these various classifications of ores are superimposed on maps showing the zones of Precambrian (cratonal), Paleozoic, Mesozoic and Cenozoic folding. The particular interest of this paper is that the author has made this survey as a preliminary to dividing the earth's surface into metallogenic provinces (of which he distinguishes 21), giving a brief discussion of each and showing its connection to areas of different ages and geotectonic structures. The ultimate aim is to construct “prognostic maps”, or maps drawn on such a basis that they may be used to predict the occurrence of a given ore or ores in a given region. — Paul T. Broneer