PORTLAND    CEMENT    MATERIALS    IN    EASTERN    WYOMING.       243 
This  is  a  normal  shale  with  high  silica  and  an  ideal  ratio  between 
alumina  and  ferric  oxide  and  silica.  The  magnesia  and  the  alkalies 
are  rather  low,  while  there  is  sufficient  iron  present  to  insure  a  fusible 
cement  matrix. 
Pierre  shale. — The  Pierre  shale  was  sampled  on  the  west  side  of 
the  railroad  track  three-fourths  of  a  mile  N.  20°  W.  of  Bradley  sta- 
tion. The  railroad  is  one-fourth  of  a  mile  due  east  of  the  shale 
deposit,  and  test  pits  would  doubtless  expose  similar  shale  under 
the  terrace  gravels  on  the  railroad  east  of  the  locality  sampled. 
The  shale  is  dark  gray  in  color  and  is  soft  and  fissile,  many  of  the 
beds  being  paper  thin;  ellipsoidal  masses  in  it  are  stained  by  iron, 
and  it  contains  a  very  little  selenite  (transparent  platy  gypsum). 
Without  much  question  it  could  be  worked  with  a  steam  shovel. 
The  following  analysis,  made  by  Mr.  A.  J.  Phillips,  is  that  of  a  sample 
taken  across  100  feet  of  the  rock: 
Analysis  of  Pierre  shale. 
Silica  (Si02) : 62. 34 
Alumina  (A1203) 21.  98 
Ferric  oxide  (Fe203) 7.  92 
Manganese  oxide  (MnO) 2G 
Lime  (CaO) 1.  28 
Magnesia  (MgO) 73 
Sulphuric  anhydride  (S03) 3G 
AlkaHesl(Na*0) 19 
AlkalieSi(K20) 1.71 
Water  at  100°  C 1.  83 
Ignition  loss 1.  77 
100. 27 
This  is  a  normal  shale,  scarcely  as  good  as  the  shale  last  described 
and  yet  of  fair  quality.  It  has  high  silica  and  its  combined  aluminum 
and  ferric  oxide  have  the  ratio  to  silica  of  1  to  2.2.  The  percentage 
of  sulphuric  anhydride  is  too  low  to  be  detrimental. 
GYPSUM. 
Gypsum,  suitable  for  use  as  a  set  retarder  of  Portland  cement, 
is  reported  to  occur  in  the  "Red  Beds"  south  of  Iron  Mountain. 
ECONOMIC   CONDITIONS. 
A  Portland  cement  plant  at  Iron  Mountain  should  use  for  its  raw 
materials  the  Graneros  shale  at  the  end  of  the  Bradley  spur  and  the 
Niobrara  shaly  limestone  east  of  the  same  point.  An  extension  of  the 
Bradley  spur  one-quarter  of  a  mile  long  would  connect  the  two  deposits. 
Chugwater  Creek  furnishes  sufficient  water  for  a  mill  on  the  railroad 
on  its  banks.  Coal  at  Cheyenne  is  $4  to  $5  a  ton.  To  this  price 
would  necessarily  be  added  the  freight  from  Cheyenne  to  Iron  Moun- 
tain on  the  Colorado  and  Southern  Railroad.     The  fuel  cost  alone 
