UNITED STATES MINERAL RESOURCES 



SILVER 



By Allen V. Heyl, W. E. Hall, Albert E. Weissenborn, H. K. Stager, 

 W. P. PuFFETT, and Bruce L. Reed 



CONTENTS 



Abstract of conclusions 



Introduction 



Exploitation 



Geologic environment 



Geochemistry 



Mineralogy 



Types of deposits 



Byproduct silver 



Porphyry copper deposits 



Copper-zinc-Iead replacement deposits 



and vein clusters 



Massive sulfide deposits 



Lead-zinc replacement deposits 



Mississippi Valley- and Alpine-type lead, 

 zinc, and fluorspar deposits and re- 

 lated deposits 



Copper deposits in sandstones and shales 



Native copper deposits 



Gold deposits in veins, conglomerates, 



and placers 



Nickel and magnetite deposits 



Silver as a major constituent 



Epithermal veins, lodes, and pipes 



Epithermal disseminated and breccia 



deposits 



Epithermal silver-manganese deposits _ 

 Epithermal silver-lead-zinc replacement 



deposits 



Epithermal silver-copper-barite deposits 

 Mesothermal silver-base metal veins — 

 Mesothermal cobalt-silver, cobalt- 

 uraninite-silver, and cobalt-silver- 

 zeolite deposits 



Sandstone silver deposits 



Sea-floor muds and hot-spring deposits _ 



Resources 



Identified resources 



Hypothetical resources 



Speculative resources 



Problems for research 



Selected references 



581 

 582 

 584 

 584 

 584 

 586 

 587 

 587 

 587 



588 

 588 

 589 



590 

 590 

 591 



591 

 592 

 592 

 592 



593 

 593 



594 

 594 

 594 



595 

 595 

 595 

 596 

 596 

 597 

 597 

 599 

 600 



FIGURE 



Page 

 66. Graph showing exploitation of silver in the 



United States 585 



TABLES 



120. 

 121. 



122. 



123. 



124. 

 125. 



The principal uses of silver 



Mine production of recoverable silver, 1965 and 



1969, in the United States, by States 



World mine production of silver, 1969, by 



countries 



Estimated free-world silver consumption and 



new mine production, 1949-70 



Silver resources in the United States 



Silver reserves of United States and free 



world 



Page 



582 



582 



583 



583 

 596 



596 



ABSTRACT OF CONCLUSIONS 



Silver is a major industrial metal in which a major world- 

 wide imbalance of more than 100 million ounces per year 

 exists between production and consumption. The silver used 

 in photography alone in the United States is greater than 

 our annual production, and most of this silver is not re- 

 covered for reuse. The deficit between domestic production 

 and consumption formerly was partly filled by withdrawal 

 from the U.S. Treasury silver reserves, but these reserves 

 are now depleted. During the next decade this deficit must 

 be filled by liquidation of private holdings, reclaimed silver, 

 imports, increasing new production, or by use of substitutes 

 for silver. 



Identified resources of silver in the United States comprise 

 an estimated 1,440 million troy ounces economically recover- 

 able at present prices (reserves) and an estimated 750 mil- 

 lion ounces in material nearly commercial in grade (condi- 

 tional resources). Other conditional resources that might be- 

 come recoverable at significantly higher prices are roughly 

 estimated to be of about the same magnitude as the present 

 reserves. Only about 35 percent of the identified resources is 

 in deposits that would yield silver as the main product; the 

 remaining 65 percent would be recovered as a byproduct 



U.S. GEOL. SURVEY PROF. PAPER 820 



581 



