W. David Menzie Frank J. Kleinhampl Dan L. Mosier 1986 Data on grades, tonnages, and geology of selected Tertiary epithermal precious- and base-metal vein districts associated with volcanic rocks were tabulated for ease of examination and comparison of characteristics between districts. There are 215 districts listed, with a cumulative tonnage of 709 million metric tons and average grades of 4.7 g/t Au, 224 g/t Ag, 0.16 percent Cu, 0.55 percent Pb, and 0.83 percent Zn, representing about 60 percent of world districts. application/pdf 10.3133/b1666 en U.S. G.P.O., Geologic and grade-tonnage information on Tertiary epithermal precious- and base-metal vein districts associated with volcanic rocks reports