﻿16 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  

  

  vol. 
  67 
  

  

  Excluding 
  from 
  consideration, 
  for 
  the 
  moment 
  the 
  cryptocrystal- 
  

   line 
  materials, 
  columns 
  3 
  and 
  5, 
  and 
  the 
  Brazos 
  River 
  sample, 
  col- 
  

   umns 
  8 
  and 
  9, 
  the 
  remaining 
  analyses 
  are 
  decidedly 
  similar 
  as 
  shown 
  

   by 
  the 
  following 
  comparison 
  and 
  average 
  : 
  

  

  • 
  The 
  amounts 
  here 
  indicated 
  are 
  probably 
  about 
  what 
  the 
  averages 
  would 
  be 
  were 
  these 
  constituents 
  

   accurately 
  determined 
  on 
  each 
  sample. 
  In 
  most 
  of 
  the 
  analyses, 
  owing 
  to 
  scarcity 
  of 
  material 
  Ti02 
  is 
  in- 
  

   cluded 
  with 
  Si02and 
  the 
  FeO-, 
  always 
  very 
  small 
  in 
  amount, 
  is 
  included 
  with 
  Fe203. 
  This 
  explains 
  the 
  

   high 
  summation 
  of 
  the 
  average 
  column. 
  

  

  