40  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,  PART    I. 
with  similar  bands  of  the  sulphides,  and  the  banding  is  parallel  to  the 
walls  of  the  vein.  In  many  places  the  sulphides,  chiefly  pyrite  and 
arsenopyrite,  constitute  half  the  volume  of  the  vein,  though  quartz 
is  as  a  rule  more  abundant  than  the  sulphides.  Much  of  this  ore  is 
fractured  by  movement  that  has  occurred  since  it  was  deposited,  and 
many  of  these  fractures  are  healed  by  low-grade  quartz  and  rhodo- 
chrosite.  A  seam  of  gouge,  from  1  inch  to  several  inches  wide,  gen- 
erally occurs  on  one  or  both  walls,  and  this  is  more  pronounced  where 
the  vein  itself  is  least  fractured.  More  fragments  of  the  country  rock 
are  inclosed  in  the  ore  on  the  lower  levels  than  on  the  upper  ones. 
In  the  lower  portion  of  the  mine,  about  2,600  feet  below  the  sur- 
face, according  to  authentic  records  of  the  company,  the  vein  was  as 
strong  and  persistent  as  in  the  upper  levels,  and  there  was  no  indi- 
cation that  it  was  decreasing  in  width,  although  the  values  were 
uniformly  low. 
Enriched  sulpiride  ore. — The  secondary  sulphide  ore  has  a  gangue 
of  quartz  and  rhodochrosite,  which  contain  or  occur  as  alternating 
bands  with  argentite,  proustite,  pyrargyrite,  tetrahedrite,  tennantitej 
pyrite,  and  arsenopyrite.  Galena  and  zinc  blende  are  locally  abun- 
dan  l ;  chalcopyrite  and  bornite  are  of  rare  occurrence.  This  ore  carries 
from  50  to  1,000  ounces  of  silver  and  from  $4  to  $8  in  gold.  It  extends 
nearly  to  the  surface  at  one  place  and  has  been  reported  from  level  17, 
but  by  far  the  greater  portion  of  it  occurs  from  300  to  800  feet  below 
the  surface.  Much  of  this  ore  is  fractured  and  in  many  places  the 
ribbonlike  bands  are  faulted  by  minute  normal  and  reverse  faults, 
which  are  as  a  rule  included  entirely  within  the  vein.  This  fracturing 
appears  to  have  been  produced  along  movement  planes,  which  follow 
the  vein  very  closely.  Probably  more  than  half  the  silver  values  of 
this  ore  are  contained  in  dark  ruby  silver,  or  pyrargyrite,  though  light 
ruby  silver,  or  proustite,  is  also  an  important  ore  mineral,  as  are  also 
tetrahedrite,  tennantite,  and  locally  argentite.  By  far  the  greater 
portion  of  the  ruby  silver  occurs  in  minute  veinlets  or  seams  filling 
cracks  in  the  vein,  as  films  on  the  outside  of  crushed  vein  material,  or 
as  crystals  nearly  an  inch  in  diameter  partially  tilling  solution  cavities 
in  the  vein.  These  solution  cavities  are  in  general  rudely  ellipsoidal 
in  shape  and,  although  not  connected,  their  longer  axes  lie  approxi- 
mately in  the  same  plane,  which  suggests  that  they  are  parts  of  a 
larger  cavity  which  has  been  almost  completely  refdled.  Clear  quartz 
of  later  age  than  that  of  the  remainder  of  the  vein  and  occurring  in 
many  places  as  well-defined  crystals  pointing  to  the  center  of  a  druse 
is  intimately  associated  with  the  ruby  silver  and  like  it  is  of  more 
recent  age  than  the  bulk  of  the  vein  quartz.  The  lower  portion  of  the 
zone  of  secondary  ore  does  not  uniformly  carry  high  values  in  silver. 
Between  levels  6  and  8  of  the  Granite,  about  midway  between  the 
