﻿Larsen 
  and 
  Hunt 
  — 
  Yanadiferous 
  jEgirites. 
  295 
  

  

  Analyses 
  Calculated 
  

  

  Si0 
  2 
  ( 
  + 
  Ti0 
  2 
  ) 
  52-82 
  52'94 
  

  

  Fe 
  2 
  3 
  ( 
  + 
  V 
  2 
  3 
  + 
  Al 
  a 
  O,). 
  .. 
  26-15 
  25-26 
  

  

  CaO 
  5-53 
  7*00 
  

  

  MgO( 
  + 
  FeO 
  -f- 
  MnO)__. 
  5-14 
  5*00 
  

  

  Na 
  2 
  0( 
  + 
  K 
  2 
  0) 
  10-68 
  9-80 
  

  

  While 
  there 
  is 
  a 
  slight 
  variation, 
  the 
  agreement 
  is 
  sufficiently 
  

   close 
  to 
  warrant 
  the 
  suggestion. 
  

  

  Vanadiferous 
  ^Egirite-Augite. 
  

  

  The 
  vanadiferous 
  segirite-augite 
  is 
  from 
  the 
  same 
  locality 
  as 
  

   the 
  aegirite 
  and 
  is 
  closely 
  associated 
  with 
  the 
  microcline-rich 
  

   portions 
  of 
  the 
  veins. 
  It 
  is 
  present 
  in 
  spherulites 
  of 
  radiating 
  

   libers 
  up 
  to 
  an 
  inch 
  across. 
  These 
  spherulites 
  are 
  commonly, 
  

   nearly 
  pure 
  pyroxene 
  ; 
  along 
  their 
  border 
  the 
  pyroxene 
  needles 
  

   pierce 
  the 
  grains 
  of 
  microcline, 
  quartz, 
  and 
  calcite. 
  The 
  fibers 
  

   are 
  very 
  small 
  and 
  are 
  closely 
  packed 
  so 
  that 
  no 
  material 
  was 
  

   available 
  for 
  crystal 
  measurements 
  and 
  even 
  the 
  cleavage 
  angle 
  

   could 
  not 
  be 
  determined 
  under 
  the 
  microscope. 
  

  

  Optical 
  properties. 
  — 
  The 
  pyroxene 
  is 
  grayish 
  green 
  in 
  color 
  

   Its 
  finely 
  fibrous 
  character 
  made 
  accurate 
  optical 
  measurements 
  

   impossible, 
  but 
  its 
  optical 
  properties 
  do 
  not 
  differ 
  greatly 
  from 
  

   those 
  of 
  ordinary 
  segirite-augite. 
  The 
  indices 
  of 
  refraction 
  as 
  

   measured 
  by 
  the 
  immersion 
  method 
  are 
  a 
  = 
  1*720 
  ± 
  0*003 
  

   7 
  = 
  1*747 
  =fc 
  0*003. 
  The 
  axial 
  angle 
  is 
  large, 
  and 
  the 
  extinc- 
  

   tion 
  on 
  cleavage 
  fragments 
  is 
  about 
  20° 
  (X 
  a 
  c). 
  The 
  maximum 
  

   extinction 
  in 
  the 
  section 
  was 
  24°. 
  The 
  pleochroism 
  is 
  rather 
  

   strong 
  : 
  X 
  = 
  light-green, 
  Y 
  = 
  greenish 
  yellow, 
  and 
  Z 
  = 
  pale- 
  

   yellow. 
  The 
  specific 
  gravity 
  is 
  3*42. 
  

  

  Chemical 
  properties. 
  — 
  -Material 
  for 
  the 
  chemical 
  analyses 
  

   was 
  carefully 
  selected 
  and 
  the 
  analyses 
  yielded 
  the 
  following 
  

   results 
  : 
  

  

  Mol. 
  ratio 
  

  

  Si0 
  2 
  ; 
  53-32 
  *8842| 
  

  

  Ti0 
  2 
  -38 
  *0047 
  f 
  88b9 
  

  

  Fe 
  2 
  Q 
  3 
  __ 
  12-38 
  -0770 
  ) 
  

  

  V 
  2 
  () 
  3 
  2-86* 
  -0190^ 
  -1097 
  

  

  A1 
  2 
  3 
  1-40 
  -0137) 
  

  

  CaO.__ 
  12-18 
  -2171 
  -2171 
  

  

  MgO 
  7-01 
  -1738 
  ) 
  

  

  FeO 
  3*70 
  -0514 
  V 
  -2315 
  

  

  MnO 
  *45 
  .0063 
  ) 
  

  

  Na„0 
  ._ 
  6*26 
  -1009 
  ) 
  

  

  KO 
  *26 
  *0027 
  r 
  

  

  Cr 
  2 
  3 
  trace 
  1-5508 
  

  

  H 
  2 
  0- 
  -07 
  

  

  HO 
  + 
  *13 
  

  

  100-40 
  

   * 
  A 
  duplicate 
  sample 
  gave 
  2 
  "82 
  per 
  cent. 
  

  

  