﻿50 
  Foote 
  and 
  Bradley 
  — 
  Constant 
  Composition 
  of 
  Albite. 
  

  

  The 
  albite 
  ratios 
  of 
  Table 
  II 
  are 
  recalculated 
  on 
  the 
  basis 
  

   SiO. 
  = 
  6-00 
  in 
  Table 
  III. 
  

  

  Table 
  III. 
  

  

  Si0 
  2 
  

  

  A1 
  2 
  3 
  

  

  NaO 
  + 
  KO 
  

  

  Albite 
  

  

  associated 
  

  

  with 
  quartz 
  

  

  6'00 
  

  

  1-04 
  

  

  •93 
  

  

  Albite 
  

  

  associated 
  

  

  with 
  quartz 
  

  

  6-00 
  

   1-00 
  

   1-02 
  

  

  3 
  

  

  Albite 
  

  

  associated 
  

  

  with 
  corundum 
  

  

  and 
  nephelite 
  

  

  6-00 
  

  

  1-04 
  

  

  •94 
  

  

  The 
  ratios 
  in 
  ISTos. 
  1 
  and 
  3 
  are 
  practically 
  identical, 
  though 
  

   the 
  associations 
  are 
  at 
  opposite 
  extremes. 
  They 
  differ 
  con- 
  

   siderably 
  less 
  than 
  Nos. 
  1 
  and 
  2, 
  where 
  the 
  association 
  in 
  both 
  

   cases 
  was 
  with 
  quartz. 
  In 
  no 
  case 
  is 
  the 
  variation 
  greater 
  than 
  

   is 
  common 
  in 
  minerals, 
  due 
  to 
  errors 
  of 
  analysis 
  or 
  slight 
  

   impurities 
  in 
  the 
  minerals 
  themselves. 
  It 
  seems 
  fair 
  to 
  con- 
  

   clude, 
  therefore, 
  that 
  no 
  solid 
  solution 
  of 
  quartz, 
  corundum 
  or 
  

   nephelite 
  in 
  albite 
  occurs 
  which 
  is 
  greater 
  than 
  the 
  appar- 
  

   ent 
  variation 
  in 
  composition, 
  due 
  to 
  the 
  ordinary 
  errors 
  of 
  

   analysis. 
  

  

  Chemical 
  and 
  Mineralogical 
  Laboratories 
  of 
  the 
  

  

  Sheffield 
  Scientific 
  School 
  of 
  Yale 
  University, 
  

  

  New 
  Haven, 
  Conn., 
  April, 
  1913. 
  

  

  