gbant.]  ZINC    AND   LEAD    OF    SOUTHWESTERN    WISCONSIN.  309 
separated  from  each  other  by  ordinary  jigging.  Still  tlio  marcasite 
percentage  in  the  cleaned  ore  is  frequently  low  enough  to  allow  the 
ores  to  be  used  by  the  zinc  smelters,  and  in  cases  where  the  marcasite 
percentage  is  higher  the  ores  arc  sold  to  the  Mineral  Point  Zinc  Com- 
pany for  use  in  the  manufacture  of  sulphuric  acid  and  zinc  oxide.  A 
few  of  the  mine-  have  installed  roasters  and  magnetic  separators,  and 
thus  the  quality  of  the  ore  is  increased.  The  results  in  this  work 
seem  to  be  very  satisfactory.  In  fact  it  is  claimed  that  ore  running  60 
to  62  per  cent  zinc  is  produced  in  this  manner,  and  that  price-  above 
$40  per  ton — in  one  can-  as  high  as  $47  have  been  obtained.  The 
problem  of  the  marcasite  impurities  in  the  zinc  ores,  which  is  a  very 
important  one  in  this  region,  thus  appear-  to  have  been  solved  in  a 
satisfactory  manner,  and  steps  are  now  being  taken  to  build  more 
roasters  and  magnetic  separators. 
Some  experiments  have  been  made  on  the  separation  of  the  marca- 
site from  the  sphalerite  by  static  electricity.  If  this  can  be  success- 
fully and  economically  done  the  marcasite,  which  after  roasting  is  now 
unsalable,  can  be  used  in  acid  making.  In  a  few  of  the  mills  concen- 
trating tables  have  been  introduced,  but  their  use  has  not  become 
common. 
PRODUCTION 
Tiie  annual  zinc  output  of  the  district  i>  probably  about  20,000  tons, 
selling  for  a  little  less  than  a  half  million  dollars.  To  this  should  be 
added  approximately  $135,000  realized  from  the  sale  of  3.00c  ion-  of 
galena,  and  a  few  thousand  from  iron  sulphide  (marcasite),  which 
si  has  recently  begun  to  be  produced  in  commercial  quantities  in  the 
vicinity  of  Mont  fort. 
CONCLUSIONS. 
In  the  Wisconsin  region  there  still  exist  above  the  level  of  ground 
water  considerable  quantities  of  galena  and  smithsonite.  Below  the 
level  of  ground  water  are  extensive  bodies  of  sphalerite,  at  time- 
mixed  with  galena.  There  i-  good  reason  to  believe  that  such  bodies 
of  sphalerite  will  last  for  a  uumber  of  year-  and  that  a  considerable 
mining  industry  will  be  here  carried  on.  The  present  high  prices  of 
lead  and  spelter,  coupled  with  the  fact  that  the  lower  grade-  of  sul- 
phide ore-  can  be  brought  up  to  higher  grades  by  roasting  and  mag- 
netic separation,  make  the  outlook  promising. 
Explorations  should,  in  the  main,  be  carried  on  by  deeper  work  in 
areas  which  have  already  produced  considerable  quantities  of  galena 
and  smithsonite  above  the  level  of  ground  water.  While  it  i-  not  to 
be  expected  that  below  every  area  which  ha-  produced  these  ore-  in 
the  higher  level>  there  are  deposits  of  sulphide  ore-  of  zinc  (or  of 
zinc  and  lead)    of  economic  value,  still  this   fact  ha-   been   demon- 
