68  CONTEIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bull.  260. 
The  quartzite  is  seamed  by  irregular  branching-  fissures,  generally 
nearly  vertical  in  position,  sometimes  extremely  narrow  and  at  others 
as  much  as  '2  inches  or  even  6  inches  in  width.  The  displacement 
along  these  is  very  slight.  The  maximum  observed  was  10  inches. 
These  are  filled  with  white  crystalline  quartz  and  almost  always 
show  a  perfect  comb  structure.  The  wider  portions  show  open  vugs 
lined  with  quartz  crystals.  The  fissures  intersect  one  another  in  two 
prevailing  directions,  though  many  local  variations  and  irregularities 
occur.  Usually  they  pass  upward  into  the  shales,  where  they  are 
generally  lost,  but  on  Cascade  Creek  they  pass  up  into  the  porphyry 
sheet,  which  rests  directly  on  the  quartzite.  They  are  therefore  later 
than  the  porphyry.  A  few  of  the  fissures  are  Avide  enough  to  be 
termed  "  fissure  veins,*'  and  carry  ore  minerals  in  sufficient  quantity  to 
be  mined  as  such,  but  these  are  uncommon. 
Along  the  course  of  the  fissures  ore  bodies  or  shoots  extend  out- 
ward for  sometimes  as  much  as  20  feet.     In  the  most  typical  cases 
these   shoots   are   irregular   bodies,   ranging   from   a    few   inches   to 
15    feet   in   thickness,   longer   in   the   direction   of   the   fissure   than 
across  it,  and  with  their  larger  dimensions  in  a  horizontal  position. 
They  are  often  exceedingly  irregular,  wandering  through  the  quartz- 
ite in  all  directions,  but  generally  being  concentrated  along  a  definite 
bed,  usually  just  under  a  very  fine  shale  band,  which  is  sometimes 
so  thin  that  it  can  be  detected  only  when  the  rock  is  broken  par- 
allel to  it.     In  the  vicinity  of  the  supplying  fissures  the  shoots  are 
at  times  pear-shaped,  with  their  longer  axes  in  a  vertical  position  and 
with  the  fissure  passing  down  through  the  small  end,  but  away  from 
the  fissures  they  are  flat  and  have  their  longer  axes  parallel  to  the  I 
planes   of   stratification   of  the   quartzite,  the   ore   solutions  having  j 
seemingly  passed  laterally  along  the  bedding.     The  largest  shoots  lie  J 
immediately  beneath  the  black  shale  at  the  top  of  the  quartzite.     Sev-j 
era!  tiers  of  shoots  sometimes  occur  along  a  single  fissure. 
The  ore  in  these  masses  is  located  chiefly  near  the  supplying  fissures 
where  it  forms  a  solid  mass,  but  outward  along  the  strata  it  but  par 
tially  fills  open  cavities,  often  merely  lining  the  interior  of  the  oper 
space.     On  the  extreme  outer  limit  of  the  shoots  nothing  but  empt* 
cavities  lined  with   quartz   crystals   are  to  be  seen.     These  contaii 
no  ore  whatever,  and  frequently  extend  for  30  feet  beyond  the  or 
shoot.     It  is  a  saying  among  the  miners  that  as  soon  as  one  find  si 
crystals  in  the  quartzite  there  will  be  no  more  ore.     These  empty  cavi  j 
ties  have  all  the  characteristics  of  cavities  produced  by  solution  i:ij 
limestone  and  can  in  no  wise  be  distinguished  from  them  except  fo 
the  lithological  character  of  the  parent  rock.     There  can  be  no  que* 
tion  that  they  were  produced  by  solution. 
The  ore  was  first  discovered  on  the  face  of  the  quartzite  cliff  an 
occurred  in  irregular  open  cavities,  which  were  exposed  by  the  breal 
