102  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull. 225. 
pah11  vein,  and  crosses  Mizpah  Hill  in  an  east-west  direction,  showing 
a  strong  outcrop.  This  outcrop  is  cut  off  both  to  the  east  and  to  the 
west  by  heavy  faults,  so  that  it  is  adjoined  on  the  east  by  therhyolite 
of  Oddie  Mountain  and  on  the  west  by  the  later  andesite.  From  the 
Mizpah  vein  a  succession  of  branches  depart,  running  chiefly  in  a 
southwestern  direction  from  the  eastern  end  of  the  outcrop,  and  each 
successive  branch  diverges  more  than  its  predecessor  from  the  strike 
of  the  main  vein,  so  that  the  whole  group  is  like  a  section  of  the 
spokes  of  a  wheel,  the  spokes  uniting  some  distance  east  of  the  main 
shaft.  The  chief  of  these  branches  are  known  as  the  Burro  No.  1, 
No.  2,  No.  3,  etc.  They  are  strongest  near  the  main  vein,  and  those 
which  diverge  most  from  the  strike  of  the  latter  are  weaker  than  those 
which  are  more  nearly  parallel  to  it.  The  intersections  of  the  branches 
with  the  main  vein  and  with  one  another  usually  pitch  to  the  east  at 
a  moderate  angle.  These  easterly  pitching  intersections  are  signifi- 
cant, since  they  have  the  same  general  curse  as  certain  shoots  of 
especially  rich  ore  in  the  same  vein,  and  correspond  also  in  direction 
to  some  post-mineral  fracturing  and  faulting.  The  main  vein  has  in 
general  a  steep  northerly  dip,  which  is  locally  overturned  so  as  to  dip 
steeply  to  the  south. 
The  Valley  View  mine  shows  a  group  of  veins  of  the  same  general 
type  as  the  Mizpah,  but  with  minor  differences.  The  main  Valley 
View  vein  as  exposed  in  the  workings  has,  like  the  Mizpah  vein, 
a  northerly  dip,  but  is  very  much  flatter.  It  is  very  large,  and  the 
rich  ore  in  it  is  unequally  distributed,  occurring  in  shoots  or  bunches. 
As  the  large  vein  approaches  the  surface  it  splits  into  several  some- 
what smaller  veins,  which  assume  a  nearly,  or  quite,  vertical  posi- 
tion. This  vein  group  is  in  general  very  nearly  parallel  to  the  Miz- 
pah group;  the  linked  character,  forking  and  reuniting,  is  quite  as 
well  marked  as  in  the  Mizpah  group;  and  there  is  some  radiation  in 
the  strike  of  the  veins,  although  not  so  much  as  in  the  former  case. 
The  Valley  View  veins  are  affected  by  post-mineral  faulting,  like  the 
Mizpah  vein. 
The  Montana  Tonopah  group  shows  a  strong  main  vein  running 
east  and  west  and  dipping  north  at  a  moderate  angle.  A  number  of 
lesser  veins  have  been  cut  in  the  workings,  and  although  development 
at  the  time  of  the  writer's  examination  was  comparatively  slight,  it  is 
probable  that  most  of  these  veins  will  eventually  unite  with  one 
another  or  with  the  trunk  vein.  The  indications  are  that  the  branches 
lie  mostly  on  the  north  side  of  the  trunk  vein  and  diverge  in  trend 
from  it,  opening  out  to  the  east.  These  branches  as  a  rule  dip  more 
steeply  than  the  main  vein,  and  will,  therefore,  also  tend  to  unite 
with  it  vertically.  The  Montana  Tonopah  veins  are,  like  the  others,  | 
displaced  by  considerable  post-mineral  faulting. 
In  all  these  veins  the  union  of  two  branches  to  form  one  is  generally 
attended  by  corresponding  enrichment,  and,   conversely,  the  place 
