﻿H. 
  W. 
  Turner— 
  Gold 
  Ores 
  of 
  California. 
  379 
  

  

  lower 
  clay 
  of 
  the 
  lone 
  formation, 
  which 
  is 
  well 
  exposed 
  at 
  

   lone 
  and 
  elsewhere, 
  and 
  as 
  the 
  quartz 
  veins 
  are 
  unquestionably 
  

   in 
  the 
  clay 
  it 
  was 
  then 
  thought 
  that 
  the 
  quartz 
  veins 
  were 
  of 
  

   Tertiary 
  age. 
  The 
  quartz 
  is 
  the 
  white, 
  compact 
  kind 
  that 
  

   occurs 
  in 
  the 
  majority 
  of 
  the 
  gold 
  quartz 
  veins, 
  and 
  not 
  the 
  

   chalcedonic 
  quartz 
  known 
  to 
  exist 
  in 
  veins 
  in 
  Tertiary 
  rocks. 
  

  

  On 
  a 
  second 
  visit 
  to 
  the 
  locality 
  in 
  1894, 
  good 
  evidence 
  was 
  

   found 
  that 
  the 
  clay 
  is 
  but 
  the 
  decomposed 
  bed 
  rock, 
  which 
  is 
  

   here 
  a 
  quartz-porphyrite. 
  Pebbles 
  of 
  the 
  . 
  hardened 
  clay 
  were 
  

   found 
  in 
  the 
  lower 
  part 
  of 
  the 
  sandstone 
  and 
  along 
  some 
  sharp 
  

   contacts 
  of 
  the 
  clay 
  and 
  overlying 
  sandstone 
  it 
  was 
  noted 
  that 
  

   the 
  quartz 
  veins 
  stopped 
  short 
  at 
  this 
  contact. 
  No 
  quartz 
  veins 
  

   were 
  found 
  with 
  certainty 
  in 
  the 
  sandstone 
  itself. 
  Moreover 
  

   some 
  cracks 
  in 
  the 
  clay 
  extending 
  down 
  from 
  its 
  upper 
  sur- 
  

   face 
  were 
  filled 
  with 
  the 
  material 
  of 
  the 
  sandstone, 
  showing 
  

   that 
  these 
  cracks 
  were 
  in 
  existence 
  when 
  the 
  sandstone 
  was 
  

   being 
  deposited 
  and 
  were 
  filled 
  in 
  from 
  above. 
  At 
  the 
  head 
  

   of 
  a 
  little 
  gulch 
  on 
  the 
  west 
  side 
  of 
  the 
  hill 
  is 
  a 
  good 
  exposure 
  

   of 
  the 
  clay 
  with 
  numerous 
  quartz 
  veins. 
  The 
  latter 
  have 
  a 
  

   varying 
  course 
  dipping 
  mostly 
  north 
  at 
  angles 
  from 
  10° 
  

   upward, 
  some 
  veins 
  curving 
  very 
  noticeably 
  in 
  a 
  vertical 
  direc- 
  

   tion. 
  In 
  some 
  of 
  this 
  much 
  stained 
  and 
  discolored 
  clay, 
  por- 
  

   phyritic 
  quartzes 
  are 
  to 
  be 
  seen, 
  and 
  as 
  lower 
  down 
  in 
  the 
  gulch 
  

   there 
  is 
  little 
  altered 
  quartz-porphyrite 
  in 
  place, 
  there 
  seems 
  

   little 
  question 
  that 
  the 
  clay 
  is 
  a 
  decomposed 
  form 
  of 
  the 
  same 
  

   rock. 
  At 
  other 
  points, 
  notably 
  on 
  the 
  east 
  side 
  of 
  the 
  hill 
  the 
  

   white 
  clay 
  shows 
  no 
  evidence 
  of 
  its 
  derivation 
  from 
  the 
  bed 
  

   rock, 
  being 
  of 
  even 
  texture 
  throughout 
  and 
  without 
  discolora 
  

   tion. 
  Slickensided 
  surfaces 
  were 
  noted 
  in 
  the 
  clay 
  at 
  several 
  

   points, 
  along 
  seams 
  that 
  intersect 
  at 
  varying 
  angles. 
  

  

  Tetrahedrite. 
  — 
  This 
  sulphide 
  of 
  copper 
  and 
  antimony 
  has 
  

   not 
  often 
  been 
  noted 
  by 
  the 
  writer 
  in 
  the 
  gold 
  ores 
  of 
  the 
  

   Sierra 
  Nevada. 
  What 
  appears 
  to 
  be 
  this 
  mineral, 
  however, 
  

   occurs 
  very 
  abundantly 
  in 
  the 
  quartz 
  veins 
  of 
  Mono 
  Pass, 
  east 
  

   of 
  the 
  Yosemite 
  Valley. 
  The 
  specimens 
  (No. 
  455 
  S. 
  N. 
  col- 
  

   lection) 
  collected 
  there 
  by 
  the 
  writer 
  from 
  the 
  Golden 
  Crown 
  

   ledge 
  were 
  examined 
  by 
  Prof. 
  P. 
  L. 
  Packard, 
  who 
  reported 
  

   that 
  the 
  sulphide 
  is 
  tetrahedrite 
  or 
  an 
  allied 
  mineral 
  giving 
  

   blowpipe 
  reactions 
  for 
  sulphur, 
  antimony, 
  copper, 
  lead 
  and 
  iron. 
  

   The 
  ore 
  is 
  presumed 
  to 
  contain 
  silver 
  and 
  perhaps 
  gold, 
  but 
  

   neither 
  of 
  these 
  were 
  determined. 
  

  

  Mr. 
  W. 
  Lindgren 
  informs 
  me 
  that 
  he 
  has 
  detected 
  tetrahe- 
  

   drite 
  at 
  the 
  following 
  mines 
  : 
  The 
  Boulder, 
  Hathaway, 
  Golden 
  

   Stag, 
  and 
  Pine 
  Tree 
  mines 
  in 
  the 
  Ophir 
  district 
  in 
  Places 
  

   County 
  ; 
  the 
  Osborne 
  Hill 
  mine 
  at 
  Grass 
  Valley, 
  Nevada 
  

   County 
  ; 
  and 
  the 
  Miller 
  & 
  Holmes, 
  Knox 
  & 
  Boyle, 
  and 
  

   Whiskey 
  Hill 
  in 
  Tuolumne 
  County, 
  azurite 
  being 
  associated 
  

   with 
  the 
  tetrahedrite 
  in 
  the 
  last 
  three 
  mines. 
  

  

  