A variety of evidence suggests that the fluids forming stratiform and red-bed copper deposits derived their Cu, Ag, and other metals from adjacent red sandstones and shales. To examine variability in relative adsorption of 0.5 mg/l Ag, Co, Cu, Ni, Pb, and Zn, adsorption on goethite has been measured as a function of pH, temperature and redox state. The observed range of metal associations in red-bed and stratiform copper deposits seems explainable by variations among districts in pH, Eh, temperature, major element content of pore fluid, and Fe oxide character of the diagenetic environment. Similar adsorption phenomena may account for varying metal ratios in other low-temperature ore deposits and in noneconomic metal enrichments. -from Authors