COPPER    DEPOSITS    OE    HARTVTLLE    UPLIFT,    WYOMING.  105 
?le  recrystallized  detrital  iron  ores  which  occur  at  the  base  of  the 
guernsey  formation  and  which  have  been  derived  from  the  mechan- 
cal  breaking  down  of  pre-Cambrian  iron-ore  bodies.  ( See  pp.  1 94-1 95.) 
The  deposits  were  not  laid  down  in  the  sea  in  the  form  in  which  they 
iowr  exist.  This  is  shown  by  the  fact  that  they  are  not  evenly  dis- 
tributed at  the  base  of  the  Guernsey  formation,  as  well  as  by  the 
straight-lined  contacts  between  copper-stained  masses  and  those 
}hat  are  unstained  by  it  and  by  the  occurrence  of  the  copper  minerals 
Is  veinlets  in  fractures.  It  is  believed,  however,  that  the  blanket 
ieposits  were  segregated  by  descending  and  laterally  moving  waters 
from  copper  that  was  widely  distributed  in  the  Guernsey  formation, 
rhis  copper,  presumably  derived  originally  from  fissure  veins  in  the 
3re-Cambrian  rocks,  was  probably  included  in  the  Guernsey  deposits 
is  either  a  mechanical  or  a  chemical  impurity  at  the  time  that  forma- 
tion wTas  laid  down  beneath  the  sea.  As  Emmons a  suggests,  clays 
nay  have  precipitated  the  copper  from  the  sea  waters,  exercising 
;he  peculiar  selective  property  called  adsorption  by  Kohler.b  That 
iaolinitic  substances  have  acted  as  powerful  agents  in  the  recrystal- 
ization  of  the  ores  is  shown  by  the  replacement  of  the  kaolinitic 
naterial  both  in  the  cement  of  the  sandstone  and  in  the  feldspars. 
From  analogy  with  the  iron  deposits  at  the  base  of  the  Guernsey 
!ormation  ( see  pp.  1 98,  203) ,  it  is  probable  that,  had  heavy  fragments  of 
copper  ore  formed  a  part  of  the  sand  of  the  Carboniferous  sea,  they 
would  naturally  be  concentrated  in  the  small  sink  holes  characterizing 
;he  surface  of  the  pre-Cambrian  limestone.  Fragmental  copper  ore 
.s,  however,  not  observed  in  any  of  the  deposits.  The  deposit  at  Silver 
Jliff,  as  before  stated,  may  be  of  different  origin,  and  the  copper  here 
nay  have  been  deposited  by  water  ascending  along  the  fault. 
THE    COPPER    BELT    MINES    COMPANY'S    HOLDINGS. 
For  convenience  the  mines  and  prospects  of  the  Copper  Belt  Mines 
Company  will  be  described  together.  These  properties,  which  are 
grouped  around  the  corner  common  to  sections  2,  3,  10,  and  11,  T. 
30  N.,  R.  64  W.,  lie  on  rugged  hills  half  a  mile  west  of  the  highest 
peak  of  the  Rawhide  Buttes.  The  rocks  in  the  vicinity  are  of  pre- 
Dambrian  age  and  comprise  an  interbedded  series  of  limestones  and 
schists,  and  a  granite  and  its  associated  pegmatite  intrusive  in  them, 
which  are  probably  equivalents  of  the  pre-Cambrian  rocks  near  Hart- 
ville.  The  limestones  are  crystalline,  fine  to  medium  grained,  and 
white.  The  schists  are  more  thoroughly  metamorphosed  than  those 
in  the  vicinity  of  Hartville.  The  folding  of  the  series  is  in  many 
places  very  close,  and  the  strike  of  the  formations  is  broadly  from 
northeast  to  southwest. 
a  Emmons,  S.  F.,  Bull.  U.  S.  Geol.  Survey  No.  260,  1905,  p.  2.32. 
b  Kohler,  Ernest,  Zeitschr.  prakt.  Geologie,  February,  1901,  pp.  44-.r>9.     See  also  Sullivan,  Eugene, 
Economic  Geology,  vol.  1, 1905,  pp.  67-73. 
