﻿296 
  Larsen 
  and 
  Hunt 
  — 
  Vanadiferous 
  ^Egirites. 
  

  

  If 
  we 
  deduct 
  from 
  the 
  molecular 
  ratios 
  given 
  above 
  the 
  

   equivalent 
  of 
  segirite, 
  namely, 
  Na 
  2 
  0, 
  Fe 
  2 
  3 
  4Si0 
  2 
  , 
  as 
  follows 
  : 
  

  

  Na 
  2 
  + 
  K 
  2 
  0) 
  -1097 
  

  

  Fe 
  2 
  3 
  ( 
  + 
  V 
  2 
  3 
  + 
  A1 
  2 
  3 
  ) 
  -1097 
  

  

  Si0 
  2 
  ( 
  +Ti0 
  2 
  ) 
  -4388 
  

  

  •6582 
  

   There 
  would 
  remain 
  

  

  Si0 
  2 
  ( 
  + 
  Ti0 
  2 
  ) 
  -4501 
  

  

  CaO 
  _ 
  -2171 
  

  

  MgO( 
  + 
  FeO 
  + 
  MnO) 
  -2315 
  

  

  •8987 
  

  

  1-5569 
  

  

  As 
  in 
  the 
  segirite 
  the 
  constituents 
  in 
  the 
  residue 
  approximate 
  

   diopside, 
  CaO.Mg0.2Si0 
  2 
  . 
  In 
  this 
  case 
  we 
  are 
  dealing 
  with 
  

   an 
  isomorphous 
  mixture 
  of 
  about 
  43 
  per 
  cent 
  segirite 
  and 
  57 
  

   per 
  cent 
  diopside. 
  A 
  comparison 
  of 
  the 
  analysis 
  with 
  the 
  cal- 
  

   culated 
  composition 
  of 
  such 
  a 
  pyroxene 
  shows 
  : 
  

  

  Analysis 
  Calculated 
  

  

  Si0 
  2 
  ( 
  + 
  Ti0 
  2 
  ) 
  53-70 
  54-01 
  

  

  Fe 
  2 
  ° 
  3 
  ( 
  + 
  V 
  A 
  + 
  A1 
  2 
  3 
  ).___ 
  16-64 
  14-88 
  

  

  CaO 
  12-18 
  14-78 
  

  

  MgO( 
  + 
  FeO 
  + 
  MnO) 
  11-16 
  10-56 
  

  

  Na 
  2 
  0( 
  + 
  K 
  2 
  0) 
  6-52 
  5-77 
  

  

  