30  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,  PART    T. 
and  one4  of  those  fissures  is  followed  by  the  main  tunnel  and  ineline 
shaft.  Xear  the  foot  of  the  ineline  shaft  the  trend  of  the  fissure  is 
nearly  due  north,  but  farther  in  it  turns  to  the  northeast,  and  though 
in  places  it  dips  very  steeply  to  the  northwest  or  southeast,  its  general 
attitude  is  about  vertical.  Ore  is  found  in  this  fissure  in  rather  small 
shoots,  which  pitch  to  the  north.  Where  examined  the  fissure  was 
not  over  3J  feet  wide,  and  the  ore  was  considerably  broken,  crushed, 
and  mixed  with  gouge.  This  indicates  strong  movement  since  the 
deposition  of  the  ore  and  closer  examination  shows  that  the  ore 
occupies  the  interstices  of  older  fissure  breccia  and  has  perhaps  slightly 
impregnated  the  walls.  The  ore  is  chiefly  galena  and  tetrahedriti 
associated  with  sphalerite,  pyrite,  and  chalcopyrite,  the  whole  being 
mixed  with  vein  quartz.  Thin  sections  of  the  fissure  walls  studied 
under  the  microscope  show  that  mineralization,  particularly  silicifica- 
tion  and  pyritization,  has  penetrated  for  a  considerable  distance  into 
the  country  rock.  About  70  tons  of  ore  have  been  shipped  to  date, 
and  nearly  as  much  more  lies  in  the  bins  ready  for  shipment.  The 
latter  is  estimated  by  the  manager  to  contain  12  to  15  per  cent  copper] 
$10  to  $12  in  gold,  50  to  (>()  ounces  in  silver,  and  10  per  cent  zinc. 
Since  the  fissure  has  never  been  followed  t<>  any  great  depth  below  the 
tunnel,  it  seems  likely  that  other  shoots,  as  large  as  the  one  excavated, 
might  be  uncovered  at  Lower  levels.  Indeed,  since  the  time  of  visit  it 
has  been  reported  thai  ore  has  been  struck  in  the  new  shaft  which  was 
then  being  sunk  for  the  purpose  of  intersecting  this  and  like  veins  at 
greater  depth. 
The  O.  K.  tunnels  are  located  north  o\'  Lake  Fork  and  several 
hundred  feet  west  of  Cooper  Creek.  They  are  short  tunnels  upon  an 
east-west  fissure  system,  but  seemasyel  not  to  have  uncovered  ore  ol 
any  account . 
CONCLUSIONS. 
Where  ore  bodies  assume  a  certain  mode  of  occurrence,  others  of 
similar  character,  as  a  rule,  occur  in  the  same  locality.  Hence,  in 
districts  where  ore  is  distributed  in  veins,  as  near  Whitecross,  the 
likelihood  of  discovering  new  veins  is  strong  enough  to  give  high 
encouragement  to  the  prospector.  Such  veins,  of  course,  are  most 
evident  on  barren  ridges  and  summits,  but  may  be  no  less  numerous 
and  valuable,  though  not  so  easily  found,  on  forest-clad  slopes. 
Thus  in  the  valley  bottoms  many  lodes  may  lie  in  bed  rock,  hidden  by 
debris,  talus,  or  soil.  The  uniformly  small  size  of  the  shoots  in  this 
area,  however,  leads  to  the  expectation  that  new  discoveries  will  not 
be  more  promising  than  those  already  made.  It  would  seem  that  the  - 
small  veins  so  far  opened,  as  well  as  virgin  property,  might  be  more 
successfully  exploited  by  a  consolidation  of  interests.  Moreover,  the 
grade  of  the  ore  suggests  that  prospecting  should  not  be  carried  on  in  a 
manner  which  precludes  drainage  by  gravity. 
