298  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.        [bull.  200. 
native  silver,  pyromorphite,  and  occasionally  a  little  malachite  or 
azurite.  Limonite,  of  course,  is  always  present,  and  results  from  the 
oxidation  of  the  p}^rite  and  the  siderite.  Plattnerite  occurred  in  the 
upper  tunnels  of  the  You  Like  vein. 
The  average  content  of  the  ores  in  silver  is  a  little  over  half  an 
ounce  to  each  per  cent  of  lead  per  ton.  During  the  fiscal  year  1903—1: 
the  ore  of  the  Bunker  Hill  and  Sullivan  mine  averaged  8.8  per  cent 
of  lead  and  3.9  ounces  of  silver.  The  first-class  concentrates  from 
the  same  mine  averaged  55  per  cent  lead  and  19.5  ounces  of  silver 
to  the  ton.  The  ore  of  the  Morning  mine  in  1903  had  an  average 
tenor  of  7.4  per  cent  of  lead  and  2.9  ounces  of  silver  per  ton.  The 
average  contents  per  ton  of  ore  in  the  Helena-Frisco  mine  in  1903 
were  4.5  per  cent  of  lead  and  2.7  ounces  of  silver.  Such  ore,  however, 
is  unprofitable.  In  1897  the  average  of  the  same  mine  was  5.5  per 
cent  of  lead  and  4.2  ounces  of  silver.  Probably  the  richest  ore  now 
produced  on  a  large  scale  is  that  of  the  Hercules,  with  approximately 
50  per  cent  of  lead  and  45  ounces  of  silver  to  the  ton.  This,  how- 
ever, is  picked  material,  as  this  mine  does  not  at  present  concentrate 
any  of  its  ore. 
Treatment  of  the  ores. — The  Hercules  mine  ships  only  crude  ore. 
The  Bunker  Hill  and  Sullivan,  Last  Chance,  and  Hecla  mines  ship 
a  little  crude  or  picked  ore,  which  in  no  case  exceeds  2  per  cent  of  the 
total  tonnage  mined,  or  7  per  cent  of  the  total  shipping  product.  The 
greater  part  of  all  the  ore  mined  is  concentrated  in  the  district  to  a 
product  containing  from  50  to  00  per  cent  of  lead.  The  number  of 
tons  of  ore  reduced  to  1  ton  of  concentrates  varies.  Of  the  low-grade 
Gold  Hunter  ore,  about  12  tons  are  required  to  make  a  ton  of  concen- 
trates containing  50  per  cent  of  lead  and  55  to  GO  ounces  of  silver. 
In  the  Bunker  Hill  and  Sullivan  mill  7^  tons  of  ore  containing  from 
8  to  1G  per  cent  of  lead  and  from  3.6  to  G.8  ounces  of  silver  to  the  ton 
are  concentrated  to  1  ton  containing  about  55  per  cent  of  lead  and 
19.5  ounces  of  silver.  From  900  to  1.000  tons  of  ore  are  treated  daily 
in  this  mill,  and  about  the  same  quantity  in  the  Morning  mill.  The 
combined  Standard  and  Mammoth  mills  treat  from  1,000  to  1.200  tons' 
daily.  The  saving  effected  in  the  best  mills  is  about  80  per  cent  of  the 
total  market  value  of  the  lead  and  silver. 
The  ore  and  concentrates  from  the  Bunker  Hill  and  Sullivan  mine 
go  to  the  Tacoma  smelter,  owned  by  the  company,  where  they  are' 
smelted  with  concentrates  from  the  Treadmill  mine,  on  Douglas 
Island.  The  Hercules  ore  also  goes  westward,  to  the  Selby  Smelting 
and  Refining  Company,  in  California.  The  concentrates  from  the 
Hecla  are  shipped  to  the  Ohio  and  Colorado  Smelting  and  Refining 
Company,  at  Salida,  Colo.  Most  of  the  ore  from  the  other  mines  goes 
to  the  various  plants  of  the  American  Smelting  and  Refining  Com- 
