SOUTHWESTERN    NEVADA    AND    EASTERN    CALIFORNIA.  57 
pyrite  free  gold  lodged  in  the  cavities  of  the  altered  monzonite  and  at  Gold  ('rater  was 
deposited  along  joints  in  the  surrounding  iron-stained  monzonites. 
Deposits  in  rhyolite. — (1)  S'.lver  and  gold  bearing  quartz  veins  in  s T.oXied  and  kaolinized 
rhyolite:  At  Silverbow,  Eden,  Cactus  Spring,  Wilsons  Camp,  Stonewall  Mountains,  and 
Wellington  vuggy  quartz  veins,  often  with  crustification  well  developed,  fill  fault  fissures, 
joint  planes,  and  cavities  of  breeciation  and  solution.  These  deposits,  ;f  not  demonstrably 
of  contemporaneous  origin,  were  formed  by  sim'lar  solutions.  The  original  sulphides 
include  stephanite,  iron  pyrites,  and  chalcopyrite.  Pyrargyrite,  also  noted,  may  be  sec- 
ondary. From  the  primary  ores  free  gold,  horn  silver,  malachite,  azurite,  limonite,  and 
hematite  are  derived.  The  relative  abundance  of  silver  sulphides  or  of  pyrite  determines 
whether  the  veins  carry  predominant  silver  or  gold  values.  In  the  same  camp  structurally 
similar  veins  carry,  respectively,  gold  and  silver,  and  in  various  portions  of  the  same  vein 
the  proportion  of  the  two  metals  varies  greatly.  These  deposits  are  evidently  the  work  of 
ascending  waters,  which  deposited  quartz  and  sulphides  in  open  crevices.  The  s'licifica- 
tion  and  mineralization  extended  in  many  instances  beyond  the  walls  of  the  crevices. 
(2)  Gold  ores  in  fault  zones:  At  Blakes  Camp  free  gold  has  been  panned  from  crushed 
rhyolite  along  a  fault.  The  iron  pyrite  was  probably  originally  disseminated  in  the  crushed 
zone. 
(3)  Gold  ores  along  Tertiary  lava  and  limestone  contacts:  A  quartz  vein  at  Southern 
Klondike  is  situated  along  the  contact  of  rhyolite  with  Cambrian  limestone.  At  the  Happy 
Hooligan  mine  tree  gold  occurs  in  decomposed  rock  at  the  contact  of  basalt  with  Ordo- 
vician  limestone. 
Relative  ages  of  the  Tertiary  deposits. — It  is  believed  that  the  first  two  subdivis'ons  of  the 
ore  deposits  in  rhyolite  are  contemporaneous,  while  the  third  may  be  so  also.  The  relative 
ages  of  the  deposits  in  monzonitic  rocks  and  rhyolite  are  unknown  The  monzonite  is 
older  than  the  rhyolite,  but  the  deposits  may  be  of  approximately  contemporaneous  age. 
DESCRIPTION   OF  CAMPS. 
The  description  of  the  camps  is  arranged  by  counties,  since  in  many  camps  several  types 
of  ore  deposits  occur.  The  mines  of  Esmeralda  County  are  described  in  order  from  north 
to  south.  In  Nye  County  the  mines  of  the  Kawich  Range  (Silverbow,  Eden,  Blakes 
Camp,  and  Kawich)  are  first  described;  then  those  of  the  Cactus  Range  (Cactus  Spring  and 
Wellington);  next  those  of  the  Ralston  Mesa  (Trappmans  Camp,  Wilsons  Camp,  and  Gold 
Crater),  and  lastly  the  remaining  camps  in  the  county. 
ESMERALDA    COUNTY,  NEV. 
Foothills  of  Lone  Mountain. — In  the  northwest  corner  of  the  area  surveyed  and  separated 
from  the  main  mass  of  Lone  Mountain  to  the  northwest  are  hills  whose  borders  are  cut  by 
narrow  canyons.  The  Cambrian  limestones  and  shales  are  here  complexly  folded,  although 
the  major  folds  have  axes  coursing  from  northeast  to  southwest.  The  sedimentaries  are 
cut  by  irregular  masses  of  dior.te  and  by  dikes  and  sheets  of  diorite-porphyry. 
When  visited  by  the  writer  m  June,  1905,  the  General  Thomas  mine,  of  the  Tonopah- 
Belcher  Mining  Company,  was  closed  down.  Several  inclines  follow  the  steeply  dipping 
beds  of  limestone  and  shale,  which  in  the  vicinity  are  injected  by  sheets  of  diorite-porph  \ty. 
Cerussite,  malachite,  azurite,  and  chrysocolla  in  altered  limestone  heavily  stained  by  limon- 
ite were  seen  on  the  dump.  Gypsum  was  simultaneously  formed  with  the  secondary  min- 
erals. Galena  and  pyrite  in  calcite  were  the  only  original  sulphides  seen,  but  some  copper 
sulphide  must  also  occur.  Mr.  Arthur  Lakes  a  states  that  lenticular  bodies  of  "sand"  car- 
bonate of  lead  containing  nodules  of  unaltered  galena  lay  along  the  contact  of  porphyry 
and  limestone,  as  well  as  in  the  limestone  itself.  The  ore  is  said  to  carry  high  silver  values. 
A  carload  shipment  made  in  January,  1904,  netted  $4,300.     At  that  time  the  shaft  was  150 
a  Mm.  and  Sci.  Press,  vol.  88,  p.  246. 
