﻿E. 
  V. 
  Shannon 
  — 
  Bismutoplagionite. 
  167 
  

  

  ated 
  prisms 
  of 
  the 
  mineral 
  but 
  these 
  were 
  not 
  terminated 
  

   and 
  were 
  too 
  minnte 
  for 
  measurement. 
  The 
  specific 
  

   gravity 
  of 
  the 
  mineral 
  is 
  5-35 
  ; 
  hardness 
  2-8 
  ; 
  streak, 
  dark 
  

   brownish-gray, 
  dull. 
  Before 
  the 
  blowpipe 
  alone 
  on 
  char- 
  

   coal, 
  it 
  fuses 
  to 
  a 
  brittle 
  globule 
  and 
  yields 
  a 
  coating 
  

   which 
  is 
  yellow 
  nearest 
  the 
  assay 
  and 
  white 
  in 
  its 
  outer 
  

   portion. 
  With 
  sodium 
  carbonate, 
  is 
  reduced 
  to 
  a 
  metal- 
  

   lic 
  button 
  yielding 
  similar 
  coatings 
  on 
  the 
  coal. 
  In 
  the 
  

   closed 
  tube, 
  yields 
  a 
  copious 
  sublimate 
  of 
  sulphur 
  ; 
  in 
  the 
  

   open 
  tube, 
  gives 
  abundant 
  sulphur 
  dioxide 
  and, 
  at 
  a 
  high 
  

   temperature, 
  a 
  heavy 
  sublimate 
  which 
  is 
  yellow 
  while 
  hot 
  

   and 
  yellowish 
  white 
  when 
  cold. 
  With 
  potassium-iodide- 
  

   sulphur 
  mixture 
  yields 
  the 
  usual 
  bismuth 
  reaction. 
  

  

  The 
  mineral 
  for 
  analysis, 
  which 
  was 
  free 
  from 
  impuri- 
  

   ties 
  other 
  than 
  pyrite, 
  was 
  completely 
  dissolved 
  in 
  hot 
  

   concentrated 
  hydrochloric 
  acid 
  while 
  the 
  pyrite 
  remained 
  

   for 
  the 
  most 
  part 
  undissolved. 
  The 
  portion 
  given 
  as 
  

   insoluble 
  in 
  the 
  table 
  below 
  consisted 
  almost 
  entirely 
  of 
  

   pyrite. 
  Upon 
  analysis 
  the 
  powdered 
  mineral 
  gave 
  the 
  

   following 
  results 
  : 
  

  

  Bismutoplagionite, 
  Montana. 
  

  

  Insoluble 
  18-88 
  

  

  PbS 
  30-21 
  

  

  As 
  2 
  S 
  3 
  trace 
  

  

  CuS 
  trace 
  

  

  Ag 
  9 
  S 
  trace 
  

  

  FeS 
  2 
  1-25 
  

  

  Sb 
  2 
  S 
  3 
  3-37 
  

  

  Bi 
  2 
  S 
  3 
  45-62 
  

  

  Total 
  99-33 
  

  

  Deducting 
  impurities 
  and 
  recalculating 
  to 
  100% 
  this 
  

   gives 
  : 
  

  

  PbS 
  3813 
  

  

  Sb 
  2 
  S 
  3 
  : 
  4-26 
  

  

  Bi 
  2 
  S 
  3 
  57-61 
  

  

  Total 
  10000 
  

  

  These 
  values 
  yield 
  the 
  following 
  ratios 
  : 
  

  

  PbS 
  1594 
  or 
  15-94 
  or 
  504 
  

  

  Bi 
  2 
  S 
  3 
  -1125 
  / 
  12-65 
  4-00 
  

  

  Sb 
  2 
  S 
  3 
  -0140 
  y 
  

  

  