PORTLAND    CEMENT    MATERIALS    IN    EASTERN    WYOMING.       235 
limestone  (about  10  per  cent)  would  make  Portland  cement  of  high 
grade. 
LIMESTONE. 
MinnekaMa  limestone. — The  Minnekahta  limestone  is  exposed  on  the 
east  side  of  wStockade  Beaver  Creek,  where  it  forms  the  slopes  and  top 
of  the  lower  of  two  benches.  Here  it  is  a  rather  thin-bedded  lime- 
stone of  light-gray  or  purplish  color,  averaging  less  than  40  feet  in 
thickness.  It  includes  at  some  places  a  few  nodules  of  flint,  but  these 
can  be  easily  separated  from  the  pure  limestone  in  the  manufacture  of 
Portland  cement,  and  where  the  rock  was  sampled  they  seem  to  be 
absent.  The  localities  at  which  samples  were  taken  are  respectively 
| J  and  2|  miles  north  and  a  little  east  of  the  L  A  K  ranch,  on  the  east 
side  of  Stockade  Beaver  Creek  and  the  road.  Analysis  1,  below,  is  by 
Mr.  P.  H.  Bates;  analysis  2  is  by  Mr.  A.  J.  Phillips. 
Analyses  of  Minnekahta  limestone. 
Constituent. 
Silica  (SiCV) 
Alumina  (A1203) 
Ferric  oxide  (Fe203) 
Manganese  oxide  (MnO). . . 
Lime  (CaO) 
Magnesia  (MgO) 
Sulphuric  anhydride  (S03). 
Alkalies.. {|^5°  ;;;; 
Water  at  100°  C. ...... .... 
Ignition  loss 
100. 37 
1.08 
1.42 
.33 
.68 
.77 
.40 
.40 
.  11 
53.40 
52.85 
.57 
.72 
.12 
.12 
.36 
.76 
.16 
.30 
.20 
.10 
42.  92 
42.78 
100. 24 
This  is  a  pure  limestone  and  an  excellent  constituent  of  a  Portland 
cement  mixture,  containing  low  magnesium  carbonate  and  sulphur. 
The  supply  of  limestone  here  is  practically  inexhaustible,  and  since  the 
bed  dips  gently  to  the  west,  the  rock  could  be  readily  quarried  and 
shot  down  to  or  nearly  to  the  railroad  by  gravity.  A  branch  railroad 
could  be  built  from  the  main  line  to  either  point  cheaply. 
PaJiasapa  limestone. — The  Pahasapa  limestone  is  exposed  in  a  thin 
band  about  1  \  miles  west  of  Stockade  Beaver  Creek.  An  analysis  of 
the  rock  bv  Mr.  P.  II.  Bates  is  as  follows: 
Analysis  of  Pahasapa  linns/one. 
Silica  (Si02) 4. 
Alumina  ( A1203) 
Ferric  oxide  (Fe203) 
Manganese  oxide  (MnO) 
Lime  (CaO) 36. 
Magnesia  (MgO) 14. 
