﻿378 
  H. 
  W. 
  Turner 
  — 
  Gold 
  Ores 
  of 
  California. 
  

  

  The 
  thin 
  sections 
  show 
  that 
  there 
  is 
  carbonate, 
  probably 
  

   chiefly 
  dolomite 
  mixed 
  with 
  the 
  mariposite. 
  This 
  with 
  some 
  

   carbonate 
  of 
  iron 
  was 
  extracted 
  with 
  acetic 
  acid 
  followed 
  by 
  

   warm 
  dilute 
  HC1. 
  the 
  mariposite 
  substance 
  remaining 
  unat- 
  

   tacked. 
  Dr. 
  Hillebrand 
  calls 
  attention 
  to 
  the 
  resemblance 
  of 
  

   the 
  mineral 
  in 
  composition 
  to 
  pinite, 
  and 
  states 
  that 
  no 
  definite 
  

   formula 
  is 
  deducible. 
  He 
  determined 
  the 
  specific 
  gravity 
  of 
  

   the 
  green 
  mineral 
  to 
  be 
  2*817 
  at 
  29*5° 
  C. 
  and 
  that 
  of 
  the 
  

   white 
  mineral 
  to 
  be 
  2*787 
  at 
  28*5° 
  C. 
  The 
  occurrence 
  of 
  

   chromium 
  in 
  the 
  green 
  variety 
  and 
  not 
  in 
  the 
  white 
  suggest 
  

   that 
  to 
  be 
  the 
  cause 
  of 
  the 
  green 
  color. 
  While 
  resembling 
  

   talc 
  optically 
  it 
  will 
  be 
  noted 
  that 
  the 
  chemical 
  composition 
  

   is 
  very 
  different. 
  

  

  Gold 
  quartz 
  veins 
  in 
  Tertiary 
  Rocks. 
  — 
  Precious 
  metal 
  

   deposits 
  in 
  rocks 
  of 
  the 
  Tertiary 
  period 
  are 
  not 
  uncommon 
  in 
  

   the 
  western 
  United 
  States. 
  As 
  notable 
  examples 
  of 
  this 
  may 
  

   be 
  mentioned 
  the 
  Comstock 
  lode 
  in 
  Nevada 
  in 
  part 
  at 
  least 
  in 
  

   Tertiary 
  lavas, 
  and 
  the 
  gold 
  and 
  silver 
  veins 
  of 
  the 
  Bodie 
  dis- 
  

   trict 
  in 
  hornblende-andesite.* 
  Silver 
  deposits 
  also 
  occur 
  in 
  

   rhyolite 
  in 
  Southern 
  California. 
  f 
  But 
  in 
  the 
  Sierra 
  Nevada 
  

   gold 
  quartz 
  veins 
  in 
  any 
  but 
  the 
  Paleozoic 
  or 
  Jura-Trias 
  rocks 
  

   are 
  rare. 
  The 
  occurrence 
  of 
  quartz 
  with 
  native 
  gold 
  in 
  a 
  

   rhyolite 
  dike 
  of 
  Tertiary 
  age 
  in 
  Plumas 
  County 
  has 
  already 
  

   been 
  described.;); 
  The 
  gold 
  in 
  the 
  Silver 
  Mountain 
  district 
  in 
  

   Alpine 
  County 
  (Markleeville 
  atlas 
  sheet) 
  is 
  in 
  chalcedonic 
  

   quartz 
  in 
  Tertiary 
  andesitic 
  tuffs 
  and 
  the 
  deposits 
  of 
  the 
  Moni- 
  

   tor 
  district 
  are 
  likewise 
  in 
  Tertiary 
  volcanic 
  rocks. 
  One 
  of 
  the 
  

   ore 
  specimens 
  given 
  the 
  writer 
  by 
  Judge 
  Arnot 
  as 
  coming 
  

   from 
  the 
  last 
  district 
  is 
  chalcedonic 
  quartz 
  containing 
  gold. 
  In 
  

   both 
  these 
  districts 
  the 
  rocks 
  containing 
  the 
  deposits 
  are 
  much 
  

   decomposed 
  by 
  solfataric 
  action, 
  and 
  both 
  are 
  on 
  the 
  east 
  slope 
  

   of 
  the 
  range 
  in 
  the 
  Great 
  Basin 
  drainage. 
  

  

  About 
  one 
  and 
  a 
  half 
  miles 
  south 
  of 
  La 
  Grange 
  in 
  Stanislaus 
  

   County 
  (Sonora 
  atlas 
  sheet) 
  in 
  a 
  flat-topped 
  hill 
  there 
  are 
  

   abundant 
  veins 
  of 
  white 
  quartz 
  in 
  clay 
  which 
  appears 
  at 
  first 
  

   glance 
  to 
  be 
  the 
  basal 
  portion 
  of 
  the 
  Tertiary 
  clastic 
  series 
  that 
  

   caps 
  the 
  hill. 
  Overlying 
  the 
  clay 
  is 
  a 
  sandstone 
  containing 
  

   pebbles 
  of 
  white 
  quartz 
  and 
  pearly 
  scales 
  of 
  a 
  hydrous 
  silicate 
  

   of 
  alumina, 
  which 
  is 
  very 
  abundant 
  in 
  the 
  lone 
  sandstone.§ 
  

   The 
  age 
  of 
  the 
  sandstone 
  is 
  thought 
  to 
  be 
  Miocene. 
  Portions 
  

   of 
  the 
  underlying 
  clay 
  are 
  white 
  in 
  color, 
  other 
  portions 
  

   stained 
  pinkish 
  in 
  streaks 
  and 
  patches. 
  When 
  first 
  visited, 
  

   some 
  years 
  ago, 
  the 
  clay 
  appeared 
  to 
  the 
  writer 
  to 
  represent 
  the 
  

  

  * 
  This 
  was 
  first 
  noted 
  by 
  Mr. 
  W. 
  Lindgren. 
  

  

  \W. 
  Lindgren, 
  Trans. 
  Am. 
  Inst. 
  Mng. 
  Eng., 
  February, 
  1887. 
  

  

  \ 
  This 
  Journal, 
  vol. 
  xlvii, 
  p. 
  472. 
  

  

  § 
  American 
  Geologist, 
  vol. 
  xiii, 
  p. 
  240. 
  

  

  