﻿H. 
  W. 
  Turner 
  — 
  Gold 
  Ores 
  of 
  California. 
  

  

  377 
  

  

  But 
  as 
  both 
  these 
  rocks 
  are 
  altered 
  forms 
  of 
  deep-seated 
  igneous 
  

   rocks, 
  it 
  does 
  not 
  follow 
  that 
  the 
  silica 
  of 
  any 
  particular 
  quartz 
  

   vein 
  was 
  leached 
  out 
  of 
  the 
  wall 
  rock 
  and 
  re-deposited 
  nearly 
  

   in 
  place. 
  These 
  igneous 
  masses 
  may 
  extend 
  to 
  a 
  great 
  depth 
  

   and 
  the 
  ascending 
  hot 
  waters 
  and 
  gases 
  may 
  have 
  been 
  in 
  con- 
  

   tact 
  with 
  rock 
  like 
  the 
  wall-rock 
  for 
  a 
  long 
  distance 
  and 
  for 
  a 
  

   considerable 
  time. 
  

  

  As 
  a 
  matter 
  of 
  fact, 
  quartz-veins 
  are 
  more 
  common 
  in 
  Cali- 
  

   fornia 
  in 
  sedimentary 
  rocks 
  which 
  are 
  not 
  presumed 
  to 
  extend 
  

   deep 
  into 
  the 
  earth's 
  crust, 
  than 
  in 
  igneous 
  masses. 
  The 
  cause 
  

   of 
  this 
  is 
  more 
  probably 
  a 
  physical 
  than 
  a 
  chemical 
  one, 
  for 
  

   fissures 
  form 
  more 
  readily 
  in 
  sedimentary 
  than 
  in 
  massive 
  

   igneous 
  rocks. 
  It 
  is 
  extremely 
  likely 
  that 
  the 
  sedimentary 
  

   series 
  of 
  the 
  Gold 
  Belt 
  of 
  California 
  is 
  underlain 
  throughout 
  

   by 
  granite, 
  and 
  that 
  this 
  rock 
  is 
  the 
  chief 
  source 
  of 
  the 
  silica 
  

   of 
  the 
  quartz 
  veins 
  in 
  the 
  clay 
  slates, 
  and 
  other 
  associated 
  rocks. 
  

  

  Serpentine 
  being 
  a 
  rock 
  in 
  which 
  fissures 
  may 
  be 
  supposed 
  

   to 
  form 
  with 
  difficulty, 
  it 
  is 
  by 
  no 
  means 
  improbable 
  that 
  there 
  

   is 
  a 
  physical 
  as 
  well 
  as 
  a 
  chemical 
  reason 
  for 
  the 
  lack 
  of 
  quartz 
  

   veins 
  in 
  that 
  rock. 
  

  

  Mariposite. 
  — 
  The 
  green 
  micaceous 
  mineral 
  called 
  mariposite 
  

   by 
  Silliman 
  occurs 
  abundantly 
  at 
  the 
  Josephine 
  Mine 
  near 
  

   Bear 
  Valley. 
  Several 
  specimens 
  of 
  this 
  were 
  obtained 
  in 
  1893, 
  

   and 
  submitted 
  to 
  Prof. 
  F. 
  W. 
  Clarke 
  for 
  analysis. 
  Thin 
  sec- 
  

   tions 
  of 
  the 
  material 
  were 
  made 
  and 
  these 
  show 
  that 
  the 
  min- 
  

   eral 
  is 
  micaceous, 
  nearly 
  colorless 
  or 
  slightly 
  greenish 
  with 
  

   brilliant 
  polarizing 
  colors, 
  resembling 
  talc. 
  There 
  appears 
  

   to 
  be 
  no 
  perceptible 
  pleochroism. 
  The 
  mineral 
  is 
  in 
  the 
  form 
  

   of 
  fibers 
  and 
  minute 
  irregular 
  foils 
  with 
  ragged 
  edges, 
  and 
  

   extinguishes 
  nearly 
  or 
  quite 
  parallel 
  to 
  the 
  longer 
  axis 
  of 
  the 
  

   fibers. 
  Macroscopically 
  it 
  is 
  not 
  all 
  green, 
  some 
  of 
  it 
  being 
  

   nearly 
  white. 
  Two 
  analyses 
  are 
  appended 
  by 
  Dr. 
  Hillebrand, 
  

   one 
  of 
  the 
  green, 
  and 
  the 
  other 
  of 
  the 
  white 
  mineral. 
  

  

  of 
  Mariposite. 
  {4.38 
  Sierra 
  Nevada 
  Coll.) 
  

  

  Green. 
  

  

  Si0 
  2 
  . 
  

  

  Tio; 
  

  

  Al 
  a 
  O, 
  

  

  o 
  2 
  o; 
  

  

  Fe 
  2 
  3 
  

   FeO. 
  

   CaO. 
  

   MgO 
  

  

  55 
  

  

  25 
  

  

  K 
  2 
  

  

  (Li 
  Na) 
  2 
  5 
  

  

  H 
  3 
  Ot_ 
  — 
  

  

  •35 
  

  

  •18 
  

   •62 
  

   •18 
  

   •63 
  

   •92 
  

   •07 
  

   •25 
  

   •29 
  

   •12 
  

   •52 
  

  

  White. 
  

   56-79 
  

  

  25-29 
  

  

  none. 
  

  

  1-59 
  

  

  •07 
  

   3-29 
  

   8-92 
  

  

  •in 
  

  

  4-72 
  

  

  100-13 
  100-84 
  

  

  * 
  Very 
  "strong 
  lithium 
  reaction. 
  -fNo 
  water 
  given 
  off 
  below 
  300 
  C. 
  

  

  \ 
  Containing 
  some 
  K 
  2 
  0. 
  

  

  Am. 
  Jour. 
  Sci.— 
  Third 
  Series, 
  Yol. 
  XLIX, 
  No. 
  293.— 
  May, 
  1895. 
  

   25 
  

  

  