﻿168 
  W. 
  H. 
  Weed 
  — 
  Gold-bearing 
  Hot 
  Spring 
  Deposit. 
  

  

  Survey, 
  and 
  No. 
  III. 
  from 
  Steamboat 
  Springs, 
  Nevada 
  (Wood- 
  

   ward).* 
  

  

  A 
  specimen 
  of 
  the 
  auriferous 
  hematite 
  from 
  this 
  mine 
  possesses 
  

   a 
  stalactitic 
  structure, 
  and 
  must 
  have 
  formed 
  in 
  a 
  cavernous 
  

   space 
  in 
  the 
  sinter. 
  Similar 
  siliceous 
  ironstones 
  are 
  formed 
  

   about 
  the 
  hot 
  springs 
  of 
  the 
  Yellowstone, 
  by 
  the 
  oxidation 
  of 
  

   the 
  cooled 
  overflow 
  waters 
  of 
  the 
  springs 
  as 
  they 
  drip 
  into 
  

   cavities 
  and 
  holes 
  in 
  the 
  sinter 
  deposits. 
  

  

  Analysis 
  of 
  Siliceous 
  Sinter. 
  

  

  L 
  II. 
  III. 
  

  

  Silica._ 
  _. 
  94-02 
  93-88 
  92*67 
  

  

  Alumina. 
  . 
  | 
  1*72 
  ) 
  

  

  ferrous 
  oxide 
  \ 
  0*14 
  j 
  

  

  Lime 
  0*07 
  0-25 
  0-14 
  

  

  Magnesia 
  trace 
  0*07 
  0*05 
  

  

  Soda 
  0-28 
  0*18 
  

  

  Potash 
  0-23 
  0*75 
  

  

  Sulph. 
  acid 
  _ 
  0-20 
  

  

  Chlorine 
  

  

  Sodic 
  chloride 
  ... 
  .... 
  0*18 
  

  

  Water 
  (105°).... 
  1-07 
  ) 
  „.„* 
  J 
  

  

  Ignition 
  2*29 
  \ 
  \ 
  

  

  5-45 
  

  

  Total.. 
  99-72 
  100*33 
  100*04 
  

  

  Two 
  peculiar 
  specimens 
  of 
  the 
  earthy 
  portions 
  of 
  the 
  ore- 
  

   mass 
  are 
  thus 
  described 
  by 
  Dr. 
  Jack 
  in 
  a 
  letter 
  to 
  the 
  writer. 
  

   " 
  It 
  occurs 
  surrounded 
  by 
  siliceous 
  sinter 
  on 
  the 
  southern 
  slope 
  

   of 
  the 
  mountain 
  35 
  feet 
  perpendicularly 
  beneath 
  the 
  surface, 
  

   and 
  39 
  feet 
  from 
  the 
  mouth 
  of 
  the 
  tunnel 
  on 
  No. 
  3 
  bench. 
  

   The 
  rock 
  is 
  full 
  of 
  tortuous 
  anastomosing 
  glazed 
  pipes 
  resem- 
  

   bling 
  worm 
  borings," 
  and 
  has 
  throughout 
  a 
  sort 
  of 
  volitic 
  struc- 
  

   ture. 
  In 
  thin 
  section 
  the 
  rock 
  is 
  seen 
  to 
  be 
  composed 
  largely 
  of 
  

   feldspathic 
  material 
  and 
  opaline 
  silica, 
  showing 
  occasional 
  crys- 
  

   tal 
  grains. 
  In 
  the 
  hand-specimen 
  the 
  rock 
  appears 
  to 
  be 
  formed 
  

   of 
  an 
  aggregation 
  of 
  pellets 
  averaging 
  a 
  millimeter 
  in 
  diameter. 
  

   These 
  pellets 
  possess 
  a 
  compact 
  outer 
  envelope, 
  about 
  a 
  more 
  

   open 
  cavernous 
  center, 
  and 
  are 
  formed 
  entirely 
  of 
  white 
  opaline 
  

   silica. 
  Grains 
  of 
  white 
  decomposed 
  rock, 
  a 
  leached 
  eruptive, 
  

   with 
  occasional 
  grains 
  of 
  quartz 
  are 
  also 
  common. 
  The 
  net- 
  

   work 
  of 
  channels, 
  and 
  concretionary 
  pellets, 
  which 
  char- 
  

   acterize 
  this 
  rock, 
  is 
  a 
  not 
  uncommon 
  structure 
  of 
  the 
  

   calcareous 
  deposits 
  of 
  the 
  Yellowstone 
  Park, 
  and 
  is 
  due 
  to 
  the 
  

   ascent 
  of 
  gas 
  bubbles, 
  through 
  the 
  soft 
  mass. 
  Siliceous 
  sinters 
  

   have 
  also 
  been 
  found, 
  possessing 
  a 
  honeycombed 
  structure 
  of 
  

  

  * 
  Reports 
  of 
  40th 
  Par. 
  Survey, 
  vol. 
  ii, 
  p. 
  826. 
  

  

  