106  CONTRIBUTIONS    TO   ECONOMIC    GEOLOGY,  1905. 
The  Mammoth  lode  trends  N.  80°  E.  and  is  traceable  for  300  feet  in  length  and  200  feet 
in  depth.  The  dip  is  30°  NW.  The  ore  is  chiefly  pyrite,  with  disseminated  chalcopyrite 
and  zinc  blende,  and  a  little  quartz.  It  is  said  to  be  owned  by  the  General  Electric 
Company. 
The  Shasta  King  (Trinity  Copper  Company)  ore  body  is  basin  shaped,  with  a  north-south 
course,  and  is  delimited  by  fissures.     The  ore  carries  barite  locally. 
The  Balaklala  is  said  to  belong  now  to  the  White  Knob  Copper  Company.  The  deposit 
is  marked  In'  heavy  gossan,  and  is  the  probable  extension  of  the  Shasta  King.  The  ore  is 
a  low-grade  mixture  of  pyrite,  chalcopyrite,  and  a  scanty  quartz  gangue.  The  main  ore 
body  is  up  to  20  feet  thick,  trends  N.  70°  E.,  dips  northwest,  and  pitches  northeast.  The 
ore  body  is  followed  for  1,000  feet  on  the  course  and  50Q  feet  on  the  dip. 
The  Spread  Eagle,  King  Copper,  and  Lorraine  properties  are  still  prospects. 
The  Foothill  copper  belt  is  in  part  mapped  and  described  in  folio  No.  11  of  the  Geologic 
Atlas  of  the  United  States.  The  chief  interest  in  this  region  is  in  the  two  copper  belts 
near  Copperopolis,  Calaveras  County,  where  the  lone,  Caledonia,  Union,  and  Napoleon 
mines  are  found.  The  ore  consists  of  chalcopyrite  and  quartz.  The  Napoleon-Camp  Seco 
lode  lies  3  miles  west  of  the  Copperopolis  lode.  At  the  Union  mine  the  lode  is  a  vein  of 
black  pyritous  slate  in  a  belt  of  amphibole  schist,  identical  in  age  and  character  with  the 
Mother  Lode  vein,  12  miles  to  the  east.  The  lone  and  Caledonia,  with  the  Copperopolis 
mine,  occur  in  a  similar  belt  in  the  schist  area  just  east  of  the  western  belt  of  Mariposa 
slates. 
The  Copperopolis  vein  is  3  to  -10  feet  wide.  The  Union  or  Keystone  mine  has  an  average 
width  of  15  feet  and  carries  a  chain  of  lenticular  masses  of  chalcopyrite,  connected  by  ore 
stringers.  Three  ore  bodies  have  been  worked,  the  largest,  at  the  Union  mine,  being  2  to 
40  feet  wide,  300  feet  long,  and  000  feet  deep,  and  pitching  to  the  north,  a 
The  ore  carries  no  gold  or  silver,  and  is  exceptionally  pure,  varying  from  3  to  5£  per  cent, 
with  some  11  per  cent  smelting  ore.  The  property  is  14  miles  from  a  railway  and  40 
miles  from  tide  water. 
The  second,  or  Camp  Seco  belt,  contains  the  mines  of  the  Penn  Chemical  Company,  on 
Mokelumne  River,  20  miles  aorthwesl  of  Copperopolis.  The  vein  contains  chalcopyrite 
and  pyrite,  with  a  trace  of  zinc  and  low  values  in  gold  and  silver,  in  a  gangue  of  talcose 
schist,  clay,  and  quartz.  A  quartz-porphyry  dike  accompanies  part  of  the  vein.  The 
deepest  development  is  by  a  550-foot  shaft  at  the  Union.  A  100-ton  pyritic  smelter  is 
intermittently  in  operation. 
The  Napoleon,  the  oldest  copper  mine  of  the  State,  is  9  miles  southwest  of  Copperopolis. 
The  vein  channel  is  100  feet  wide,  and  consists  of  diabase  and  metadiabase  down  to  talcose 
schist.     The  dip  is  62°  and  the  vein  is  developed  to  250  feet  in  depth. 
At  Copperopolis  the  smelter  was  blown  in  during  December,  but  closed  for  three  weeks 
during  January.  The  ore  supplied  is  derived  from  the  Copper  King  mine,  but  as  the 
smelter  is  15  miles  from  the  railroad  and  the  fuel  is  oil,  hauled  by  traction  engine,  it  was 
obliged  to  shut  down  on  account  of  the  bad  roads. 
COLORADO. 
Colorado  has  few  producing  copper  mines.  The  copper  output  is  obtained  mainly  as  a 
by-product  of  the  precious-metal  ores  treated  in  custom  smelters.  The  production  comes 
from  eleven  different  counties,  one-third  of  it  being,  however,  from  Lake  County.  San 
Juan  County  is  the  next  largest  producer.  At  Pearl,  an  extension  of  the  Encampment, 
Wyo.,  district,  a  small  matte  smelter  erected  in  1904  is  idle  and  the  property  unproductive. 
The  production  by  counties  for  1904-5  is  given  in  the  following  table: 
«  See  Copper  Resources  of  California;  also  Mother  Lode  district:  Geologic  Atlas  U.  S.,  folio  63,  U.S. 
Gcol.  Survey,  1900. 
