216         CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY,   1907,   PART  II. 
Stein  mine. — The  Stein  mine,  2  miles  southeast  of  Gebo  mine  No.  1, 
in  the  SW.  J  sec.  18,  T.  44  N.,  R.  94  W.,  is,  like  the  Gebo  mines,  being 
developed  prior  to  the  construction  of  railroad  tracks.  A  main  gang- 
way has  been  driven  for  200  feet  and  two  entries  have  been  opened. 
Six  miners  are  employed,  with  an  output  of  20  tons  per  day.  The 
small  dump  now  in  use  and  the  horsepower  haulage  are  to  be  replaced 
by  a  large  tipple  and  a  complete  equipment  of  heavy  machinery. 
This  mine  will  probably  be  one  of  the  large  producers  of  the  field.  At 
present  coal  is  hauled  by  wagon  to  Kirby  station,  and  there  loaded 
on  cars.     The  selling  price  is  $2.50  per  ton. 
Prospecting. — The  coal  beds  in  the  Gebo  field  have  been  examined 
along  their  outcrops  by  prospectors  and  openings  made  at  short  inter- 
vals. In  the  western  part  of  the  field  the  exposures  usually  occur  in 
steep  slopes  where  talus  does  not  interfere  with  examination,  hence 
prospect  pits  are  unnecessary.  Some  mining  has  been  done  along 
Cottonwood  Creek  and  in  a  syncline  near  the  southern  edge  of  the 
area,  but  at  present  these  small  mines  are  not  operated.  In  this  part 
of  the  field  there  are  opportunities  for  small  mines,  but  no  beds  thick 
enough  to  support  extensive  mining.  In  the  eastern  part  the  beds 
have  been  opened  at  many  places  and  their  thickness  and  extent  along 
the  outcrop  determined.  No  drill  records  are  available  to  show  the 
condition  of  the  beds  down  the  dip,  but  it  seems  probable  that  they 
have  about  the  same  thickness  as  along  the  strike.  Favorable  con- 
ditions for  the  opening  of  mines  exist  near  Bighorn  River,  west  of 
the  Gebo  mines,  and  in  the  small  syncline  to  the  south. 
CHARACTER  OF  THE  COAL. 
PHYSICAL   PROPERTIES. 
The  coals  of  the  western  side  of  Bighorn  Basin  are  subbituminous. 
The  Fort  Union  and  Laramie  (?)  coals  are  black  and  the  Eagle 
brownish  black.  The  Eagle,  however,  and  to  a  less  extent  the  Lara- 
mie (?)  coals  contain  thin  lusterless  layers  alternating  with  bright 
bands,  giving  to  the  vertical  faces  of  the  bed  a  faintly  banded  appear- 
ance. On  the  other  hand,  the  Fort  Union  coal  has  a  uniform  texture 
and  is  not  banded.  Jointing  is  either  indistinct  or  absent.  The 
Eagle  coal  shows  a  moderate  tendency  to  break  along  bedding  planes 
and  less  regularly  in  perpendicular  planes,  but  the  Fort  Union  coal 
is  almost  devoid  of  regular  joints.  Specimens  from  the  various  beds 
are  medium  in  hardness  and  show  a  tendency  toward  a  small  con- 
choidal  fracture,  and  in  some  samples  of  Fort  Union  coal  there  is  a 
peculiar  pitted  structure  which  has  been  designated  by  English 
writers  as  " bird's-eye."  Some  of  the  lower  beds  contain  small  accre- 
tions of  light-brown  resin  similar  to  the  resin  balls  in  the  coal  mines 
