Examples of money axes and decorative rings from Oaxaca are found to have been made of smelted copper hammered to shape with intermediate anneals. The impurities present and the schedule of working and annealing used are different for each artifact. The ingot casting and subsequent metal forming are to a lower standard of workmanship in the rings than in the axes. The copper of highest purity found among the artifacts contains inclusions of cuprite; in the examples of less pure copper, impurities are strongly concentrated in the nonmetallic inclusions. At an arsenic concentration of 1%, both cuprite and copper arsenide inclusions are present. Unlike the cuprite inclusions, the copper arsenide inclusions are shattered during cold working of the copper. When annealed, they retain the total elongation they acquired during working and so can serve as indicators of the total amount of plastic deformation used in fabrication. Close examination of the exteriors of three money axes and consideration of their design show that it is unlikely that they served a utilitarian function.