Important quantities of gold, silver, platinum-group metals, selenium, tellurium, and arsenic are recovered in the processing of copper concentrates. The objective of this Bureau of Mines study was to determine the occurence of these elements in copper ores and to trace their distribution during subsequent processing steps. The study describes the important areas supplying concentrates, precipitates, and unrefined copper to the copper smelting and refining ndustry in a composite of the years 1971-74. The relative importance of these areas as a source of the respective byproducts is assessed. The lack of certain quantitative and assay data, recycling of dusts and slags, and the addition of scrap to the feed often complicates calculations and estimations of the byproducts in the smelter-refinery throughptus. Such volatile or low-boiling point elements as arsenic, slenium, nad tellurium may be lost in gaseous and other emissions in various processign stages, or they may be concentrated in slags and residues for which samples were not available. the effects of antipollution legislation to improve control of sulfurous and other emissions that may affect recovery of certain byprodcuts was noted. A section on newer technology illustrating hydrometallurgical techniques that may affect the recovery of minor metals is included.