HARTVILLE    IRON-ORE    RANGE,  WYOMING.  199 
samples,  since  their  analyses  from  the  same  points  show  a  higher 
content  of  phosphorus.  Some  of  the  ore  is  high  in  silica,  its  only 
other  detrimental  constituent.  Sulphur,  so  far  as  known,  is  absent, 
while  the  copper  minerals  occupy  such  restricted  areas  that  their 
presence  is  not  troublesome  in  the  sorting  of  the  ores.  The  ore  is 
rather  heavy,  occupying  approximately  10  cubic  feet  per  ton. 
DISTRIBUTION. 
The  iron  ore  lenses  all  occupy  similar  positions  in  relation  to  the 
inclosing  rocks.  They  lie  in  schist  immediately  above  the  upper- 
most limestone  of  the  older  pre-Cambrian  series.  This  limestone 
swings  from  the  Good  Fortune  mine  east  to  Whalen  Canyon,  where 
it  is  covered  by  alluvium.  Since  limestone  does  not  outcrop  on  the 
east  side  of  Whalen  Canyon  south  of  this  point  the  contact  is  perhaps 
situated  near  the  center  of  the  valley.  In  the  other  direction  the 
contact  courses  from  the  Good  Fortune  mine  north  of  west  to  a  point 
where  it  passes  beneath  horizontal  Carboniferous  rocks.  The  contact 
between  the  schist  and  limestone  in  this  direction  is  again  exposed 
in  the  Republic  shaft  at  the  tail  of  the  railroad  Y  in  Sunrise.  From 
here  it  courses  to  a  point  beneath  the  Colorado  Supply  Store,  from 
which  it  goes  north  and  then  northeast,  forming  the  foot  wall  of  the 
Sunrise  ore  body.  Thence  it  bows  out  to  the  northward,  passing 
north  of  the  Biwabik  shaft  beneath  the  Carboniferous,  and  appearing 
at  the  surface  again  100  feet  north  of  the  Chicago  open  pit.  The 
contact  here  is  hidden  in  a  valley,  but  appears  again  on  the  hill  west 
of  the  Colorado  Supply  Store  at  Ironton.  After  passing  beneath  the 
alluvium  of  Whalen  Canyon  this  contact  next  appears  in  a  hill  south 
of  the  house  at  Kline's  ranch.  From  this  point  it  courses  practically 
due  north  to  Frederick,  where  it  lies  slightly  east  of  the  ranch  house. 
Along  this  contact,  then,  all  of  the  larger  iron  deposits  of  the  Hartville 
iron  range  occur. 
The  presence  of  large  ore  bodies  is  determined  apparently  by  the 
minor  structural  peculiarities  of  this  contact.  For  instance,  in  the 
Sunrise  mine  the  two  richest  bodies  of  ore  lie  in  minor  synclines 
superimposed  upon  the  main  syncline.  At  the  Good  Fortune  mine 
the  ore  is  closely  associated  with  a  sharp  minor  fold  accompanied  by 
considerable  brecciation.  At  the  Sunrise  mine  the  hanging  wall  and 
the  foot  wall  are  both  schist,  although  on  the  foot  wall  the  schist 
between  the  ore  and  the  underlying  limestone  is  thin.  At  the  Chi- 
cago mine  the  ore  on  the  north  side  is  directly  against  the  limestone 
or  its  iron-stained  alteration  products.  At  the  Good  Fortune  mine 
a  thin  shell  of  siliceous  iron-stained  schist  separates  the  ore  from  the 
underlying  limestone.  The  contact  between  the  ore  body  and  the 
country  rock  is  in  some  places  sharp  and  in  others  gradational.  On 
the  whole,  gradational  contacts  are  probably  more  common,  and  it 
