﻿W. 
  F. 
  Foshag 
  — 
  Apthitalite 
  from 
  California. 
  367 
  

  

  Art. 
  XXVII. 
  — 
  Apthitalite 
  (Glaserite) 
  from 
  Searles 
  

   Lake, 
  California; 
  by 
  W. 
  F. 
  Foshag. 
  1 
  

  

  The 
  United 
  States 
  National 
  Museum 
  recently 
  acquired 
  

   through 
  transfer 
  from 
  the 
  United 
  States 
  Geological 
  Sur- 
  

   vey 
  boring 
  samples 
  of 
  a 
  well, 
  G 
  75, 
  sunk 
  at 
  Searles 
  Lake, 
  

   San 
  Bernardino 
  County, 
  California. 
  These 
  samples 
  

   were 
  collected 
  by 
  Mr. 
  Hoyt 
  Gale 
  during 
  some 
  of 
  his 
  in- 
  

   vestigations 
  on 
  the 
  possible 
  potash 
  deposits 
  in 
  the 
  

   United 
  States. 
  They 
  consist 
  mainly 
  of 
  halite, 
  hanksite, 
  

   trona, 
  pirssonite, 
  gay 
  lussite 
  and 
  thenardite 
  with 
  some 
  

   borax, 
  northupite 
  and 
  sulphohalite. 
  In 
  working 
  over 
  

   this 
  material 
  one 
  specimen 
  was 
  found 
  consisting 
  of 
  tabu- 
  

   ular 
  crystals 
  embedded 
  in 
  a 
  white 
  powdery 
  matrix 
  and 
  

   also 
  crystallizing 
  in 
  open 
  cavities. 
  Upon 
  close 
  examina- 
  

   tion 
  these 
  crystals 
  were 
  found 
  to 
  be 
  trigonal 
  in 
  aspect 
  

   and 
  suggested 
  the 
  mineral 
  apthitalite. 
  Tests 
  with 
  so- 
  

   dium 
  cobalti-nitrite 
  showed 
  potash 
  to 
  be 
  present 
  in 
  con- 
  

   siderable 
  amounts. 
  

  

  The 
  embedded 
  crystals 
  ranged 
  up 
  to 
  20 
  mm. 
  in 
  size 
  but 
  

   were 
  rough 
  and 
  not 
  suited 
  for 
  accurate 
  measurements. 
  

   Occasional 
  crystals 
  in 
  the 
  open 
  cavities, 
  however, 
  were 
  

   of 
  excellent 
  development 
  and 
  a 
  few 
  of 
  these 
  were 
  of 
  

   sufficient 
  brilliance 
  to 
  give 
  sharp 
  signals 
  on 
  the 
  goniome- 
  

   ter. 
  The 
  habit 
  is 
  simple, 
  the 
  only 
  forms 
  noted 
  being 
  

   the 
  base 
  and 
  the 
  rhombohedron 
  r 
  (1011). 
  Three 
  angles 
  

   measured 
  between 
  c 
  and 
  r 
  from 
  sharp 
  signals 
  gave 
  56° 
  2', 
  

   56°3 
  / 
  , 
  and 
  56° 
  4'. 
  They 
  vary 
  in 
  habit 
  from 
  very 
  thin 
  

   tabular 
  to 
  thick 
  tabular. 
  

  

  The 
  mineral 
  is 
  colorless 
  with 
  a 
  vitreous 
  luster. 
  Hard- 
  

   ness 
  3. 
  Brittle. 
  Under 
  the 
  microscope 
  the 
  mineral 
  ap- 
  

   peared 
  uniaxial 
  ( 
  + 
  ). 
  The 
  indices 
  of 
  refraction 
  meas- 
  

   ured 
  by 
  the 
  oil 
  immersion 
  method 
  were 
  found 
  to 
  be 
  

  

  to 
  ± 
  1490 
  dz 
  0003, 
  e 
  = 
  1-496 
  db 
  0-003. 
  

  

  The 
  birefringence 
  is 
  weak, 
  the 
  thickest 
  fragments 
  show- 
  

   ing 
  yellow 
  of 
  the 
  first 
  order. 
  

  

  Material 
  for 
  analysis 
  was 
  carefully 
  picked 
  out 
  but 
  

   when 
  examined 
  under 
  the 
  microscope 
  showed 
  some 
  inter- 
  

   mixed 
  halite. 
  Aside 
  from 
  the 
  halite 
  no 
  other 
  impurity 
  

   could 
  be 
  detected. 
  The 
  analysis 
  gave 
  the 
  following 
  

   results 
  : 
  

  

  1 
  Published 
  with 
  the 
  permission 
  of 
  the 
  secretary 
  of 
  the 
  Smithsonian 
  

   Institution. 
  

  

  