HAKTVILLE    IRON-ORE    RANGE,  WYOMING.  205 
enough  development  work  has  been  done  upon  the  ore  bodies  of  this 
fault  plane  to  determine  satisfactorily  either  their  commercial  possi- 
bilities or  theu  mode  of  origin.  It  is  certain  that  prospect  work 
should  be  confined  to  the  fault  contact  between  the  two  formations. 
These  iron-ore  lenses  were  deposited  by  water  which  circulated  along 
the  fault  plane.  It  is  unknown  whether  the  water  which  formed  the 
iron  ore  ascended  or  descended  along  this  plane,  although  the  close 
resemblance  of  the  ore  to  much  of  that  of  the  pre-Cambrian  type  indi- 
cates that  the  lenses  were  deposited  by  descending  waters.  In  this 
connection,  however,  the  apparent  thickening  of  the  ore  bodies  in 
depth  should  be  borne  in  mind. 
GOSSAN    DEPOSITS. 
In  the  Haystack  Mountains,  particularly  in  McCanns  Pass,  com- 
paratively large  areas  are  covered  by  a  low-grade  hematite,  with 
which  is  associated  some  limonite.  These  minerals  cement  irregular 
fragments  of  schist.  Here  and  there  small  amounts  of  iron  pyrites 
occur  and  the  deposit  is  in  every  way  similar  to  the  surface  croppings 
of  some  of  the  copper  deposits  of  the  district.  There  is  little  doubt 
that  this  deposit  is  the  gossan  or  iron  hat  of  a  sulphide  vein.  The 
mechanical  impurities  in  the  ore  are  so  finely  divided  that  its  quality 
can  not  be  bettered  by  hand  picking,  and  sulphur  is  present  as  a 
chemical  detriment. 
Bull.  315—07 14 
