﻿Realgar 
  in 
  the 
  Yellowstone 
  National 
  Parle. 
  403 
  

  

  the 
  calculated 
  angles 
  the 
  axes 
  of 
  Kokscharow* 
  have 
  been 
  taken 
  

   in 
  which, 
  

  

  a: 
  1 
  : 
  c 
  : 
  : 
  081309 
  : 
  1 
  : 
  1-90339. 
  

  

  Forms. 
  

  

  Calculated. 
  

  

  

  Measurement. 
  . 
  

  

  

  p*p 
  111*111 
  

  

  94° 
  52' 
  

  

  94° 
  

  

  51', 
  94° 
  

  

  41', 
  

  

  94° 
  

  

  40' 
  

  

  p*p 
  111*111 
  

  

  36 
  40* 
  

  

  36 
  

  

  43, 
  36 
  

  

  44 
  + 
  

  

  

  

  p^ra 
  111 
  n 
  110 
  

  

  18 
  20^ 
  

  

  18 
  

  

  20$, 
  18 
  

  

  22+ 
  

  

  

  

  p^e 
  111*101 
  

  

  36 
  47 
  

  

  36 
  

  

  45, 
  36 
  

  

  50 
  

  

  

  

  p~n 
  111*011 
  

  

  47 
  26 
  

  

  47 
  

  

  35. 
  47 
  

  

  15 
  

  

  

  

  p*% 
  111*133 
  

  

  27 
  29 
  

  

  27 
  

  

  25, 
  27 
  

  

  27, 
  

  

  27 
  

  

  30 
  

  

  p^q 
  111*131 
  

  

  29 
  10+ 
  

  

  29 
  

  

  08, 
  29 
  

  

  17 
  

  

  

  

  p^y 
  111*112 
  

  

  15 
  llf 
  

  

  ' 
  15 
  

  

  13+ 
  

  

  

  

  

  p*s 
  111*113 
  

  

  26 
  29| 
  

  

  26 
  

  

  28+ 
  26 
  

  

  30+ 
  

  

  

  

  p^t 
  111*115 
  

  

  40 
  33i 
  

  

  40 
  

  

  34 
  

  

  

  

  

  _p*c 
  111*001 
  

  

  71 
  39f 
  

  

  71 
  

  

  «i 
  

  

  

  

  

  In 
  general 
  the 
  planes, 
  even 
  though 
  minute, 
  gave 
  fair 
  reflections 
  

   owing 
  to 
  the 
  brilliancy 
  of 
  their 
  surfaces. 
  The 
  only 
  exception 
  

   to 
  this 
  was 
  the 
  plane 
  i-l 
  130, 
  from 
  which 
  no 
  satisfactory 
  reflec- 
  

   tions 
  could 
  be 
  obtained. 
  It 
  is 
  easily 
  identified 
  however 
  since 
  

   it 
  lies 
  in 
  the 
  zones 
  110,*, 
  110 
  and 
  001 
  /\ 
  131. 
  

  

  Though 
  no 
  tests 
  were 
  made 
  the 
  material 
  is 
  apparently 
  of 
  

   great 
  purity. 
  It 
  is 
  very 
  homogeneous 
  and 
  is 
  of 
  a 
  delicate 
  

   sulphur-yellow. 
  

  

  Orpiment 
  and 
  Realgar. 
  

  

  The 
  presence 
  of 
  arsenic 
  in 
  the 
  hot 
  spring 
  waters 
  of 
  the 
  Yel- 
  

   lowstone 
  Park, 
  and 
  the 
  deposition 
  of 
  the 
  hydrous 
  arseniate 
  of 
  

   iron, 
  scorodite, 
  by 
  them, 
  has 
  already 
  been 
  noticed 
  in 
  this 
  Jour- 
  

   nal.* 
  While 
  studying 
  the 
  hydro-thermal 
  phenomena 
  of 
  the 
  

   region 
  for 
  the 
  U. 
  S. 
  Geological 
  Survey, 
  under 
  the 
  direction 
  of 
  

   Mr. 
  Arnold 
  Hague, 
  a 
  careful 
  search 
  for 
  deposits 
  of 
  the 
  arseni- 
  

   cal 
  sulphides 
  was 
  rewarded 
  by 
  the 
  discovery 
  of 
  realgar 
  and 
  orpi- 
  

   ment, 
  at 
  the 
  Morris 
  Geyser 
  Basin. 
  This 
  locality, 
  though 
  pos- 
  

   sessing 
  few 
  geysers 
  worthy 
  of 
  comparison 
  with 
  those 
  of 
  the 
  

   Firehole 
  basins, 
  is 
  peculiarly 
  interesting 
  by 
  reason 
  of 
  the 
  new- 
  

   ness 
  of 
  its 
  geysers 
  and 
  the 
  great 
  variety 
  of 
  its 
  chemical 
  deposits. 
  

   It 
  covers 
  an 
  area 
  of 
  some 
  six 
  square 
  miles 
  situated 
  amid 
  the 
  

   forests 
  of 
  the 
  great 
  rhyolite 
  plateau 
  of 
  the 
  Park 
  whose 
  gradual 
  

   slopes 
  rise 
  on 
  every 
  side. 
  The 
  area 
  of 
  present 
  activity 
  is 
  

   included 
  between 
  a 
  loop 
  of 
  the 
  Gibbon 
  river 
  and 
  two 
  spurs 
  of 
  

   Gibbon 
  Hill, 
  an 
  eminence 
  of 
  rhyolite 
  that 
  rises 
  above 
  the 
  gen- 
  

   eral 
  level 
  of 
  the 
  country 
  to 
  the 
  south. 
  The 
  multitude 
  of 
  

  

  * 
  Min. 
  Russl., 
  vi, 
  p. 
  368, 
  1874. 
  

  

  * 
  A. 
  Hague, 
  this 
  Journal, 
  vol. 
  xxxiv, 
  Sept., 
  1887. 
  

  

  