138  CONTEIBUTIONS    TO   ECONOMIC    GEOLOGY,  1905. 
ledge.  Picked  samples  of  this  ore  yielded  when  assayed  about  $40  in  gold  to  the  ton.  It 
is  reported  that  average  samples  indicate  that  the  ore  will  run  not  far  from  $10  per  ton. 
Both  these  veins  appear  to  be  widest  where  they  cut  a  diabase  dike  100  feet  wide,  which 
extends  N.  80°  E.  The  effect  of  the  dike  seems  to  be  purely  mechanical,  since  away  from 
it  the  veins  show  a  tendency  to  divide  up  into  stringers. 
A  vein  called  the  Mother  lode,  situated  on  a  spur  of  Wards  Peak  about  half  a  mile  north 
of  the  boundary,  consists  at  the  surface  of  two  veins,  each  about  a  foot  thick,  which  come 
together  in  the  face  of  the  tunnel  25  feet  in  from  the  surface.  Both  these  veins  are  cut  by 
a  horizontal  fault  having  a  throw  of  about  1  foot. 
Similar  ores  occur  about  2  miles  north  of  the  boundary  around  Eagle  Peak,  and  about  5 
miles  north  of  the  boundary,  in  a  mine  owned  and  formerly  operated  by  the  Deer  Creek 
Mining  Company.  This  mine  is  equipped  with  a  small  stamp  mill,  which  was  idle  during 
the  past  season.  The  company  also  controls  some  placer  deposits  along  Deer  Creek,  on 
which  development  work  was  in  progress  in  September,  1905.  The  gold  in  the  quartz 
ledges  of  this  neighborhood  is  free  as  far  as  the  ledges  have  been  developed.  It  seems 
probable,  however,  that  in  depth  it  will  be  found  refractory  and  will  require  concentrating 
and  smelting. 
Fragments  of  quartz  similar  to  or  resembling  that  at  Wards  Peak  were  found  strewn  on 
the  surface  along  the  De  Borgia  trail  to  the  southern  limit  of  the  area  examined.  In  this 
distance  one  large  quartz  vein  10  feet  or  more  in  width  and  several  smaller  veins  were  seen. 
A  sample  from  the  large  vein  was  found  to  contain  traces  of  gold  and  half  an  ounce  of  silver 
to  the  ton.  Only  one  of  the  smaller  veins  was  sampled  and  assayed,  but  this  was  found  to 
contain  no  traces  of  gold.  In  the  altered  quartzites  and  schists  found  in  the  southwestern 
part  of  the  district  a  lew  small  quartz  veins  were  noted.  One  of  these,  which  cropped  out 
along  the  trail  near  Slide  Rock  Peak,  in  T.  44  N.,  R.  3  E.,  is  about  1  foot  thick  and  lies 
between  the  bedding  of  the  country  rock,  which  here  probably  belongs  to  the  Prichard 
formation,  though  it  is  altered  practically  to  a  mica-schist.  A  sample  taken  from  this 
vein  when  assayed  yielded  a  trace  of  gold  and  no  silver. 
Very  little  prospecting  has  been  done  in  the  southern  part  of  this  district,  and  no  pros- 
pect holes  were  seen  by  the  writer.  It  is  remote  from  settlements  and  difficult  of  access. 
The  obvious  occurrence  here,  however,  of  small  quartz  veins  carrying  traces  of  gold  seems 
to  warrant  the  belief  that  there  may  be  some  gold-bearing  veins  of  economic  value. 
RESUME  AND   CONCLUSION. 
This  region  is  practically  unexplored  and  undeveloped,  though  its  geologic  and  topo 
graphic  conditions  are  quite  similar  to  those  of  the  Coeur  d'Alene  mining  district,  to  which  it 
is  adjacent.  Prospects,  more  or  less  promising,  of  lead-silver,  copper-gold,  and  gold  ores 
have  been  found  at  many  widely  distributed  localities,  most  of  which  are  along  the  trails 
or  adjacent  to  the  larger  streams.  Commercially,  valuable  ores  have  been  produced  at 
only  one  of  these  localities. 
Most  of  the  lead-silver  prospects  are  in  the  northwestern  part,  and  the  ore  consists  of 
galena,  either  distributed  through  the  country  rocks  or  contained  in  masses  of  limonite  or 
iron  caps,  whose  relation  to  the  country  rock  has  not  yet  been  determined.  These  ores 
average  one-third  ounce  of  silver  to  1  per  cent  of  lead. 
The  copper-gold  ores  are  more  widely  distributed.  They  occur  in  definite  veins  devel- 
oped along  fault  fissures,  and  their  outcrops  are  indicated  by  gossan  stained  with  copper 
carbonate.  In  depth  the  vein  matter  consists  mainly  of  siderite,  calcite,  and  quartz, 
with  the  sulphides  of  copper  and  iron.  The  proportion  of  gold  to  copper  varies  greatly, 
though  it  seems  to  average  about  0.02  ounce  of  gold  to  1  per  cent  of  copper.  Most  of  the 
development  of  these  veins  has  been  done  in  a  belt  a  few  miles  wide  near  the  Montana-Idaho 
State  line,  where  about  500  tons  of  high-grade  ore  have  been  mined  and  shipped. 
Gold  placers  of  economic  value  are  not  known  to  occur  within  the  area  involved  in  this 
contest,  though  prospectors  report  that  fine  colors  of  gold  can  be  obtained  from  the  gravels 
. 
