58  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
feet  deep.  This  deposit  resembles  some  of  those  at  Montezuma.  Other  prospects  occur 
in  limestone  and  in  the  diorite  in  the  vicinity.  The  surrounding  hills  are  bare  of  timber, 
and  water  is  scarce.     Tonopah,  the  supply  point,  is  12  miles  distant  by  road. 
Southern  Klondike. — Southern  Klondike  is  12  miles  north  of  Goldlield  and  an  equal  dis- 
tance south  of  Tonopah.  Gold  and  silver  ores  were  discovered  here  in  March,  1899,  by 
Messrs.  J.  G.  Court  and  T.J.  Bell.  Work  has  been  carried  on  more  or  less  continuously 
since  that  date.  From  one  group  of  claims  shipments  of  ore  averaging  $200  a  ton  and  aggre- 
gating $50,000  are  reported.  Several  thousand  feet  of  tunnels,  shafts,  and  inclines  have 
been  driven.  In  June,  1905  (the  time  of  the  writer's  visit),  eight  men  were  at  work  in  the 
camp. 
The  hills  surrounding  the  camp  are  cones  and  ridges  of  low  relief.  The  predominant  for- 
mation is  a  black  Cambrian  limestone,  locally  silicified  to  a  dark  jasperoid.  Associated 
with  this  are  minor  quartzite  lenses  and  beds  of  partially  metamorphosed  shale.  The  sedi- 
mentaries  are  folded  into  an  anticline  with  a  northeast-southwest  axis.  While  some  v<  ri  <al 
beds  occur,  moderate  dips  predominate.  Small  dikes  and  irregular  masses  of  muscovite 
granite  inject  the  Cambrian  rocks.  The  granite  is  probably  of  post-Jurassic  age.  Ter- 
tiary flows  and  dikes  of  rhyohte  respectively  cap  and  cut  the  sediments. 
The  ore  deposits  are  of  three  kinds  -first,  quartz  veins  parallel  to  the  bedding  of  the 
Cambrian  rocks;  second,  quartz  veins  carrying  predominant  gold  values  along  the  contact 
of  the  sedimentaries  with  quartz-rhyolite  dikes;  third,  quartz  veins  in  granite  along  joint 
fractures.  The  last-named  veins  cany  silver-bearing  lead  ores  (galena  and  cerussite).  The 
contact  veins  show  post-mineral  faulting. 
The  quartz  veins  parallel  to  the  bedding  planes  of  the  limestones  are  of  greatest  value 
and  interest,  and  these  only  will  be  described.  They  are  tabular  lenses  of  quartz  from  a 
few  inches  to  a  foot  or  more  in  thickness.  Horses  of  limestone  are  included.  Adjacent 
veins  connected  by  cross  veins  of  quartz  or  completely  separated  by  thin  bands  of  limestone 
may  form  a  mineralized  zone  14  feet  thick.  The  quartz  appears  to  have  filled  a  fissure 
in  the  limestone.  Brecciation  of  the  limestone  accompanied  the  Assuring.  The  contact 
between  the  limestone  and  quartz  is  sharp,  and  silicification  of  the  limestone  has  not 
occurred  to  an  important  extent.  Vugs  lined  with  quartz  crystals  are  rather  character- 
istic of  the  white,  semitransparent  quartz. 
The  original  sulphides  depos.ted  simultaneously  with  the  quartz  and  disseminated  in 
small  masses  in  it  are,  in  the  order  of  their  abundance,  galena,  stetefeldite,"  and  iron  pyrites, 
The  secondary  ores  include  horn  s.lver,  chrysocolla,  malachite,  azurite,  specular  hematite, 
and  cerussite  in  brownish  granular  masses  and  to  a  less  extent  in  crystals.  These  second- 
ary minerals  surround  the  sulphides  and  (ill  cavities  and  cracks  in  the  quartz.  Some  cal- 
cite  and  gypsum,  accompanied  by  sulphur,  are  secondary  gangue  minerals.  Sulphur  some- 
times forms  masses  3  inches  in  diameter.  Assay  returns  show  from  25  to  40  per  cent  of  the 
values  in  gold,  the  rest  in  silver.  Silver  occurs  as  the  chloride  and  apparently  also  asso- 
ciated with  the  copper  minerals.     The  prospects  as  yet  are  well  above  water  level. 
In  southern  Klondike  fissures  and  brecciated  zones  were  opened  in  the  Cambrian  lime- 
stone along  bedding  planes.  Water  filled  these  cavities  with  silica  and  with  lead,  copper, 
and  iron  sulphides  carrying  silver  and  gold.  The  quartz  veins  have  since  been  fractured 
and  faulted  and  surface  waters  have  developed  a  number  of  secondary  minerals.  In  this 
district  the  presence  of  quartz  veins  at  the  contact  of  rhyolite  and  limestone  shows  the 
Tertiary  or  post-Tertiary  age  of  the  gold  veins,  but  the  presumption  is  that  the  more 
important  silver  veins  are  of  earlier  formation. 
Water  is  obtained  at  the  Klondike  wells  4  miles  distant.  When  visited,  Tonopah  was 
the  supply  and  shipping  point. 
Montezuma  district. — Montezuma  is  situated  8  miles  nearly  west  of  Goldlield  The 
Montezuma  mining  district  was  organized  in  18G7,  and  soon  afterwards  several  mines  were 
opened  in  the  country  west  of  Montezuma  Peak.     In  the  eighties  a  mill  was  erected  in 
a  Copper-silver  sulphide  reported  by  J.  E.  Spurr:  Trans.  Am.  Inst.  Min.  Eng.,  1905,  p.  961. 
