SENTINEL  BUTTE  LIGNITE  EIELD,  N.   DAK.   AND  MONT. 
35 
the  analyses  would  be  slightly  different,  especially  with  respect  to 
their  original  moisture  content,  had  the  samples  been  taken  from 
fresh  faces  of  coal,  out  of  reach  of  atmospheric  agencies. 
Proximate  analyses  of  samples  of  lignite  from  the  Sentinel  Butte  field,  North  Dakota- 
Montana. 
[F.  M.  Stanton,  chemist  in  charge.] 
Laboratory  No 
Sample  as  received: 
Moisture 
Volatile  matter 
Fixed  carbon 
Ash 
Sulphur 
Calories 
British  thermal  units 
Loss  of  moisture  on  air  drying 
Air-dried  sample: 
Moisture 
Volatile  matter 
Fixed  carbon 
Ash 
Sulphur 
Calories 
British  thermal  units 
5779 
34.50 
29.76 
28.53 
7.21 
.99 
3,730 
6,714 
21.00 
17.09 
37.67 
36.11 
9.13 
1.25 
4,721 
8,499 
5781 
5782 
35.72 
35.40 
31.88 
38.25 
23.54 
20.71 
8.86 
5.64 
1.53 
.84 
3.538 
3,781 
6,368 
6,806 
23.30  I     17.00 
16.19 
41.57 
30.69 
11.55 
1.99 
4,613 
8,302 
22.17 
46.08 
24.95 
6.80 
1.01 
4,555 
8,200 
5784 
43.51 
25.23 
24.87 
6.39 
1.04 
3,230 
5,814 
32.60 
16. 19 
37.43 
36.90 
9.48 
1.54 
4,792 
8,626 
5779.  Sec.  16,  T.  141  N.,  R.  105  W.,  North  Dakota. 
5781.  Sec.  8,  T.  141  N.,  R.  105  W.,  North  Dakota. 
5782.  Sec.  25,  T.  139  N.,  R.  105  W.,  North  Dakota. 
5784.  Sec.  5,  T.  139  N.,  R.  104  \\ .,  North  Dakota. 
ESTIMATED   TONNAGE  OF  LIGNITE. 
It  has  been  estimated  that  the  total  amount  of  lignite  in  the  field 
within  1,000  feet  of  the  surface  and  3  feet  or  more  in  thickness  is 
approximately  33,126,269,000  tons,  equivalent  to  one  bed  36.94  feet 
thick  covering  an  area  of  792  square  miles. 
MINING   OPERATIONS. 
All  mining  in  the  field  is  done  to  supply  local  demands.  One- 
eighth  of  a  mile  northeast  of  Medora  a  drift  has  been  opened  to  the 
southeast  for  70  feet  on  a  bed  of  lignite  at  the  base  of  the  bluff.  The 
same  bed  was  formerly  worked  on  the  west  side  of  Little  Missouri 
River  about  one-fourth  mile  west  of  the  railway  station  at  Medora, 
where  mining  operations  were  carried  on  by  the  Northern  Pacific 
Railway  Company  as  early  as  1884.  These  workings  have  been 
abandoned  and  the  entries  allowed  to  cave  in,  so  that  the  lignite  can 
not  now  be  seen.  Other  openings  from  which  lignite  has  been  taken 
during  the  fall  and  winter  months  are  found  at  many  points  in  the 
field.  Throughout  most  of  the  area  lignite  is  the  only  fuel  used,  and 
the  ranchmen  and  settlers  mine  and  haul  the  few  tons  they  need  from 
the  nearest  available  outcrop,  which  is  commonly  not  many  miles 
distant. 
Timber  suitable  for  mining  operations  is  scarce  except  along  the 
valley  of  Little  Missouri  River. 
