ST.   JOE    KIVER    BASItf,   IDAHO.  135 
The  Bald  Mountain  ledge,  situated  near  the  north  line  of  T.  46  N.,  R.  7  E.,  may  be 
taken  as  a  typical  example  of  the  copper-bearing  veins  in  this  belt.  This  ledge  is  developed 
by  a  tunnel  for  nearly  1,000  feet.  It  strikes  approximately  east  and  west,  but  does  not 
extend  in  an  exactly  straight  line,  and  dips  to  the  north  at  an  angle  of  about  60°.  The  ledge 
matter  varies  in  width  from  1  to  8  or  9  feet  and  consists  of  brecciated  quartzite  similar  to 
the  walls,  cemented  with  vein  matter  consisting  of  quartz,  calcite,  and  siderite,  in  which 
sulphides  of  copper  and  iron  are  contained.  At  one  point  there  is  a  definite  ore  shoot 
several  feet  thick,  extending  for  100  or  200  feet  along  the  tunnel.  The  ore  in  this  shoot 
consists  of  nearly  pure  siderite  containing  chalcopyrite  scattered  through  it.  When 
assayed  a  specimen  of  this  ore  was  found  to  contain  1.5  per  cent  of  copper,  0.02  ounce  of 
gold,  and  1  ounce  of  silver  per  ton.  At  the  face  of  the  tunnel  the  ledge  consists  of  brec- 
ciated country  rock  cemented  together  by  quartz,  with  some  calcite  and  siderite.  A 
specimen  of  the  most  promising  ore  in  the  face  was  assayed,  showing  a  trace  of  gold  and 
1.42  per  cent  of  copper.  The  croppings  of  this  ledge  are  said  to  be  easily  traceable  on 
account  of  a  heavy  "iron  cap."  Some  distance  beyond  the  end  of  the  tunnel  an  ore 
shoot  which  promises  to  be  considerably  richer  than  that  described  has  been  found  and 
toward  this  the  tunnel  is  being  extended. 
The  Monitor  mine,  also  in  T.  46  N.,  R.  7  E.,  and  about  2h  miles  southeast  from  the  Bald 
Mountain,  is  the  only  one  which  has  actually  produced  ores  on  a  commercial  scale.  It  is 
connected  with  the  railroad  at  Saltese,  Mont.,  by  a  wagon  road  5h  miles  long.  The  devel- 
opments have  not  yet  progressed  far  enough  to  tell  definitely  either  the  dimensions  of  the 
ledge  or  the  direction  of  its  strike,  but  it  is  evident  from  the  developments  already  made 
that  it  is  of  the  same  type  as  the  Bald  Mountain  ledge  already  described.  The  strike 
is  said  to  be  nearly  east  and  west  and  it  dips  about  80°  N.  The  ore  consists  of  a  great 
deal  of  brecciated  material  cemented  by  vein  matter  and  is  evidently  deposited  along  a 
fault.  That  the  movement  has  continued  since  the  deposition  commenced  is  shown  by 
slickensiding  of  some  of  the  ore.  The  mine  is  developed  by  a  shaft  to  a  depth  of  300  feet, 
and  by  short  tunnels  on  the  100,  200,  and  300  foot  levels.  Above  the  100-foot  level  nearly 
all  of  the  ore  is  oxidized  and  consists  of  hematite  and  limonite  mixed  with  the  carbonates 
of  copper.  Below  a  depth  of  125  feet,  however,  there  are  no  carbonate  ores,  and  the 
principal  copper- bearing  mineral  is  chalcopyrite  associated  with  pyrrhotite.  Evidently 
the  main  shaft  of  the  mine  has  been  sunk  directly  on  a  rich  ore  shoot  which  cropped  at 
the  surface.  The  ore  body  is  probably  at  least  10  feet  wide,  though  the  walls  are  not  yet 
well  defined  and  its  extent  has  not  been  determined.  Ores  from  this  mine  carry  con- 
siderable gold  as  well  as  copper.  In  the  oxidized  upper  portion  the  gold  value  is  often 
as  high  as  $12  per  ton,  but  below  the  60-foot  level  it  ranges  from  $3.60  to  $8  or  $9  per  ton. 
The  copper  ore  shipped  ranges  from  10  to  30  or  40  per  cent.  This  mine  was  discovered 
in  1897  and  the  first  shipment  of  ore  was  made  in  1900.  In  all,  about  500  tons  of  ore 
have  been  sent  to  the  smelter.  The  ore  is  first  hauled  by  wagon  5i  miles  to  Saltese,  Mont., 
whence  it  is  shipped  by  rail  to  Tacoma,  Wash.;  the  total  cost  of  shipping  and  smelting 
amounts  to  nearly  $8  per  ton.  Three  hundred  tons  of  the  ore  netted  the  owners  of  the 
mine  $34.85  per  ton  after  the  freight  and  smelting  charges  were  deducted. 
In  the  immediate  vicinity  of  the  Monitor  mine,  both  west  and  south  for  6  or  7  miles, 
copper-bearing  ledges  have  been  located  which  are  reported  to  be  of  the  same  general 
type.  One  of  these,  known  as  the  Buffalo,  crosses  the  Montana-Idaho  boundary  and  was 
examined  by  the  writer.  This  mine  or  prospect  is  about  8  miles  southeast  of  the  Monitor, 
and  is  being  developed  on  the  Montana  side,  where  it  is  reported  to  carry  good  prospects 
in  copper.  Where  it  crosses  the  divide  the  vein  is  exposed  in  an  open  cut.  It  is  here 
several  feet  wide  and  the  ore  consists  for  the  most  part  of  spathic  iron  containing  very 
little,  if  any^  copper  or  gold. 
Other  locations  in  this  belt  where  development  is  in  progress  and  in  which  the  general 
relations  are  believed  to  be  similar  to  those  described  are  known  as  the  Park,  Springfield, 
Champion,  Wonderful,  Eagle,  Bullion,  North  Star,  Aipino,  Richmond,  Leroy,  Wampum, 
and  Kootenai  Giant  claims  or  groups  of  claims.     Outside  of  this  belt,  which  lies  along  the 
