﻿Penfield 
  — 
  Chemical 
  Composition 
  of 
  Sulphohalite. 
  425 
  

  

  Aet. 
  XLIII. 
  — 
  On 
  the 
  Chemical 
  Composition 
  of 
  Sulphohalite 
  ; 
  

   by 
  S. 
  L. 
  Penfield. 
  

  

  The 
  rare 
  species 
  sulphohalite 
  was 
  first 
  described 
  in 
  1888 
  by 
  

   W. 
  E. 
  Hidden 
  and 
  J. 
  B. 
  Mackintosh* 
  as 
  a 
  mineral 
  of 
  unusual 
  

   composition, 
  a 
  double 
  sulphate 
  and 
  chloride 
  of 
  sodium 
  corre- 
  

   sponding 
  to 
  the 
  formula 
  3Na 
  2 
  S0 
  4 
  .2NaCl. 
  It 
  was 
  found 
  asso- 
  

   ciated 
  with 
  the 
  then 
  recently 
  discovered 
  hanksite, 
  at 
  the 
  

   famous 
  Borax 
  Lake 
  locality, 
  San 
  Bernardino 
  County, 
  Califor- 
  

   nia. 
  It 
  crystallizes 
  in 
  rhombic 
  dodecahedrons, 
  belonging 
  to 
  

   the 
  isometric 
  system 
  and 
  measuring 
  at 
  times 
  over 
  30 
  mm 
  in 
  

   diameter. 
  According 
  to 
  information 
  received 
  from 
  Mr. 
  

   Hidden, 
  only 
  a 
  few 
  specimens 
  of 
  the 
  mineral 
  were 
  found. 
  

   Two 
  of 
  these 
  are 
  in 
  the 
  collection 
  of 
  Mr. 
  C. 
  S. 
  Bement 
  of 
  

  

  Philadelphia, 
  and 
  one 
  in 
  the 
  British 
  Museum, 
  while 
  the 
  type 
  

   specimen 
  from 
  which 
  material 
  for 
  the 
  original 
  analysis 
  by 
  

   Mackintosh 
  was 
  obtained, 
  was 
  retained 
  by 
  Mr. 
  Hidden. 
  This 
  

   latter 
  specimen 
  has 
  been 
  generously 
  presented 
  to 
  the 
  writer, 
  

   with 
  the 
  understanding 
  that 
  part 
  of 
  it 
  should 
  be 
  used 
  for 
  a 
  

   new 
  analysis 
  and 
  the 
  remainder 
  deposited 
  in 
  the 
  Brush 
  Collec- 
  

   tion 
  of 
  the 
  Sheffield 
  Scientific 
  School. 
  

  

  Figs. 
  1 
  and 
  2 
  represent 
  the 
  two 
  specimens 
  in 
  the 
  Bement 
  

   Collection, 
  natural 
  size. 
  The 
  one 
  represented 
  by 
  fig. 
  1 
  is 
  a 
  

   rhombic 
  dodecahedron 
  of 
  almost 
  ideal 
  development, 
  slightly 
  

   yellowish 
  in 
  its 
  tone 
  of 
  color, 
  and 
  nearly 
  transparent. 
  A 
  very 
  

   little 
  gangue, 
  chiefly 
  hanksite, 
  and 
  a 
  few 
  small 
  crystals 
  of 
  sul- 
  

   phohalite 
  are 
  the 
  only 
  things 
  attached 
  to 
  this 
  superb 
  crystal, 
  

  

  * 
  This 
  Journal, 
  III, 
  vol. 
  xxxvi, 
  p. 
  463. 
  

  

  