COPPER    MINES    OF    THE    UNITED    STATES. 
Precious  metals  contained  in  the  copper  ores  of  each  State. 
95 
Utah 
Arizona 
Montana  (Butte) .... 
California  (Shasta) 
New  Mexico 
Colorado.. 
Appalachian  States  (esti- 
mated)   , 
Washington 
Gold. 
Ounces. 
109,968 
47,  563 
44,  400 
24, 727 
4,137 
3,288 
1,060 
582 
Silver. 
Ounces. 
2, 572, 582 
1,464,731 
10,236,119 
844,265 
79,369 
131,695 
79,600 
16,710 
Idaho 
Wyoming 
Oregon 
South  Dakota. 
Nevada 
Michigan 
Total. 
Gold. 
Ounces. 
538 
326 
326 
145 
10 
237,116 
Silver. 
Ounces. 
201,843 
4,601 
11,677 
789 
2,519 
122,807 
15,768,307 
The  distribution  of  the  copper  mines  of  the  country  is  shown  in  PI.  III. 
The  Butte,  Mont.,  copper  district  is  the  greatest  silver-producing  camp  of  the  entire 
world,  its  production  being  10,236,119  ounces  in  1904.  Utah  leads  in  the  amount  of  gold 
produced  from  its  copper  ores,  Bingham  and  Tintic  yielding  109,968  ounces,  the  ores  also 
carrying  2,572,582  ounces  of  silver.  The  Arizona  mines  yield  more  gold  than  the  Butte 
mines,  but  far  less  silver. 
GENERAL  CONDITIONS. 
The  marked  change  from  lead  to  copper  as  a  collector  of  precious  metals  in  smelting 
practice  is  one  of  the  notable  features  of  recent  years  and  has  furnished  a  market  for  gold 
and  silver  ores  whose  copper  content  was  not  formerly  paid  for,  3  per  cent  copper  being 
long  considered  the  minimum. 
The  most  striking  feature  of  copper  mining  in  the  last  two  years  is  the  complete  success 
of  experiments  made  in  the  treatment  of  the  so-called  disseminated  ores,  in  which  small 
particles  of  copper  sulphides  occur  disseminated  through  altered  porphyry.  Enormous 
bodies  of  this  class  of  ore  occur  at  Morenci,  Ariz.,  at  Bingham,  Utah,  and  at  Ely,  Nev., 
that  were  formerly  considered  of  too  low  grade  to  work,  but  that  have  been  proved  to 
yield  a  handsome  profit  when  treated  in  concentrating  mills  and  concentrated  10  to 
20  into  1. 
The  extent  to  which  these  great  bodies  of  "disseminated"  ore  will  contribute  to  the 
world's  supply  of  copper  can  be  estimated  from  the  fact  that  preparations  are  being  made 
to  mine  and  mill  12,000  tons  of  this  ore  a  day  at  Bingham  and  nearly  as  much  at  Ely, 
while  the  mills  of  both  the  companies  at  Morenci  have  been  greatly  enlarged.  Although 
similar  disseminations  of  glance  and  pyrite  in  altered  granite  alongside  of  and  between  the 
veins  at  Butte,  Mont.,  have  long  been  milled,  it  has  been  customary  to  regard  a  3  per  cent 
or  even  a  4  per  cent  ore  as  the  lowest  grade  that  could  be  profitably  treated,  whereas  at  the 
localities  mentioned  above  the  grade  is  much  lower,  as  shown  by  the  following  table,  after 
J.  P.  Charming: 
Tenor  of  " disseminated^''  copper  ores. 
Per  cent. 
Morenci,  Ariz.,  Arizona  Copper  Company 2. 6 
Morenci,  Ariz.   Detroit  Copper  Company 3. 0 
Bingham,  Utah,  Utah  Copper  Company. 1.9 
Bingham,  Utah,  Boston  Consolidated  Copper  Company  1.  4 
Ely,  Nev.,  Nevada  Consolidated  Copper  Company ,  Ruth  mine 2. 6 
Ely,  Nev.,  Nevada  Consolidated  Copper  Company,  Eureka  mine 2.  2 
It  is  evident  that  the  price  of  the  metal  will  determine  the  minimum  grade  of  copper  ore 
that  can  be  treated  at  a  profit.  The  above  ores  can  be  made  to  pay  with  copper  at  12 
cents  a  pound. 
The  widespread  adoption  of  so-called  pyritic  or  raw-sulphide  smelting,  in  which  the  fuel 
value  of  the  suiphur  is  utilized,  has  had  its  effect  on  copper  mining,  as,  indeed,  have  the 
Bull.  285—06 7 
