﻿54 
  Hess 
  and 
  Hunt 
  — 
  Triplite 
  from 
  Eastern 
  Nevada. 
  

  

  If, 
  in 
  the 
  above 
  analyses, 
  those 
  constituents 
  representing 
  

   either 
  adhering 
  matrix 
  or 
  altered 
  material 
  intimately 
  mixed 
  

   with 
  the 
  triplite 
  are 
  disregarded, 
  the 
  greatest 
  variation 
  is 
  to 
  be 
  

   found 
  in 
  the 
  proportion 
  of 
  FeO 
  to 
  MnO. 
  Inasmuch 
  as 
  the 
  

   percentage 
  of 
  FeO 
  varies 
  from 
  41*42 
  to 
  1*68 
  with 
  a 
  corre- 
  

   sponding 
  increase 
  in 
  the 
  MnO 
  from 
  23*25 
  to 
  57*63, 
  we 
  have 
  

   unquestionably 
  isomorphous 
  replacements 
  of 
  these 
  elements 
  in 
  

   all 
  proportions 
  and 
  the 
  term 
  triplite 
  must 
  be 
  considered 
  to 
  

   include 
  not 
  only 
  those 
  phosphates 
  of 
  manganese 
  high 
  in 
  iron, 
  

   but 
  likewise 
  those 
  in 
  which 
  the 
  iron 
  content 
  is 
  practically 
  

   negligible. 
  The 
  material 
  from 
  [Nevada 
  would 
  seem 
  to 
  

   represent 
  the 
  manganese 
  end 
  member 
  of 
  this 
  iron-manganese 
  

   series. 
  

  

  Blowpipe 
  and 
  physical 
  properties. 
  — 
  Triplite 
  is 
  soluble 
  in 
  

   acids. 
  Before 
  the 
  blowpipe 
  it 
  fuses 
  readily 
  to 
  a 
  black 
  globule 
  

   and 
  becomes 
  slightly 
  magnetic, 
  and 
  gives 
  a 
  manganese 
  reaction 
  

   with 
  the 
  borax 
  bead. 
  The 
  color 
  of 
  triplite 
  given 
  in 
  texts 
  as 
  

   various 
  shades 
  of 
  brown 
  and 
  black, 
  seems 
  to 
  correspond 
  to 
  

   those 
  varieties 
  rich 
  in 
  FeO 
  or 
  those 
  possessing 
  considerable 
  

   included 
  and 
  oxidized 
  material 
  ; 
  the 
  mineral 
  here 
  described 
  was 
  

   apparently 
  unaltered, 
  possessed 
  a 
  vitreous 
  luster 
  and 
  light 
  

   salmon 
  -pink 
  color. 
  Streak 
  white. 
  H 
  = 
  4 
  — 
  4|-. 
  Cleavage 
  in 
  

   two 
  directions, 
  one 
  very 
  prominent. 
  Sp. 
  gr. 
  3*79. 
  

  

  Optical 
  properties 
  . 
  — 
  The 
  material 
  was 
  entirely 
  massive 
  and 
  

   the 
  indices 
  were 
  determined 
  by 
  immersion 
  in 
  oils 
  by 
  E. 
  S. 
  

   Larsen 
  as 
  follows 
  : 
  a 
  = 
  1*650 
  = 
  1*660 
  7 
  = 
  1*672, 
  all 
  db 
  *005. 
  

   The 
  birefringence 
  is 
  about 
  *020. 
  The 
  optic 
  axis 
  emerges 
  per- 
  

   pendicular 
  to 
  one 
  of 
  the 
  cleavages. 
  A 
  very 
  large 
  optical 
  angle 
  

   is 
  shown 
  by 
  the 
  extremely 
  slight 
  curvature 
  of 
  the 
  bar 
  observed 
  

   on 
  this 
  interference 
  figure. 
  Optically 
  -f, 
  dispersion 
  p>v. 
  

   Under 
  high 
  magnification 
  some 
  of 
  the 
  fragments 
  reveal 
  dark 
  

   colored 
  rounded 
  or 
  fibrous 
  aggregates 
  of 
  included 
  material. 
  

   Similar 
  inclusions 
  were 
  reported 
  by 
  Lazarevic" 
  in 
  a 
  brown 
  

   variety 
  and 
  Stelznerf 
  is 
  of 
  the 
  opinion 
  that 
  the 
  dark 
  color 
  of 
  

   triplite 
  is 
  to 
  be 
  explained 
  by 
  the 
  unusually 
  large 
  quantities 
  of 
  

   these 
  inclusions. 
  Whether 
  or 
  not 
  this 
  supposition 
  is 
  correct, 
  

   in 
  the 
  Nevada 
  material, 
  which 
  is 
  apparently 
  unaltered 
  and 
  con- 
  

   tains 
  a 
  comparatively 
  small 
  number 
  of 
  inclusions, 
  we 
  have 
  a 
  

   variety 
  which 
  is 
  not 
  brown 
  but 
  salmon-pink 
  in 
  color. 
  

  

  * 
  Centr. 
  Min., 
  385, 
  1910. 
  f 
  Min. 
  Mitth., 
  222, 
  1873. 
  

  

  