﻿Notes 
  upon 
  the 
  Lithologt 
  of 
  the 
  Adieoistdacks. 
  95 
  

  

  plagioclase 
  feldspars 
  is 
  400, 
  how 
  closely 
  do 
  the 
  observed 
  agree 
  

   with 
  the 
  theoretical 
  densities 
  in 
  other 
  recorded 
  analyses 
  of 
  lab- 
  

   radorite? 
  We 
  shall 
  use 
  in 
  this 
  comparison: 
  — 
  I, 
  Labradorite, 
  

   from 
  Neurode, 
  Silesia, 
  occurring 
  in 
  Hyperite. 
  v. 
  Rath. 
  II, 
  

   From 
  JNTeurode(Volpelsdorf). 
  v. 
  Rath. 
  Ill, 
  Naroedal, 
  Norway. 
  

   Rammelsberg. 
  IV, 
  Berufjord, 
  Iceland. 
  Damour. 
  V 
  Eger- 
  

   sund, 
  Norway. 
  Kersten. 
  VI, 
  Havnefjord, 
  Iceland, 
  v. 
  Rath. 
  

   VII, 
  Lund, 
  Sweden. 
  In 
  Dolerite. 
  Blomstrand. 
  VIII, 
  St. 
  

   Paul's 
  Island, 
  Labrador. 
  Tschermak.* 
  

  

  i 
  

  

  atomic 
  Ratio. 
  

  

  Formula. 
  

  

  Density. 
  

  

  

  Na 
  : 
  Ca 
  

  

  

  Theoretical. 
  Observed. 
  

  

  I. 
  

  

  1 
  :3£ 
  

  

  Si 
  An. 
  + 
  1 
  Al. 
  

  

  2.7498 
  2.715 
  

  

  II. 
  

  

  1 
  : 
  3 
  

  

  3 
  An. 
  + 
  1 
  Al. 
  

  

  2.745 
  2.709 
  

  

  III. 
  

  

  1 
  :2i 
  

  

  2J 
  An. 
  + 
  1 
  Al. 
  

  

  2.739 
  2.714 
  

  

  IV. 
  

  

  1 
  : 
  2 
  

  

  2 
  An. 
  + 
  1 
  Al. 
  

  

  2.731 
  2.709 
  

  

  V, 
  VI. 
  

  

  1 
  : 
  H 
  

  

  li 
  An. 
  + 
  1 
  Al. 
  

  

  2.7208 
  2.705 
  and 
  2.729 
  

  

  VII, 
  VIII, 
  

  

  1 
  : 
  1 
  

  

  1 
  An. 
  + 
  1 
  Al. 
  

  

  2.704 
  2.68 
  and 
  2.697 
  

  

  If, 
  instead 
  of 
  assuming 
  that 
  the 
  atomic 
  volumes 
  are 
  identical, 
  

   we 
  take 
  for 
  the 
  at. 
  vol. 
  of 
  Anorthite, 
  that 
  deduced 
  from 
  its 
  

   mean 
  specific 
  gravity, 
  or 
  404, 
  and 
  furthermore 
  assume 
  that 
  the 
  

   molecules 
  of 
  the 
  constituent 
  minerals 
  occupy 
  in 
  the 
  labradorite 
  

   their 
  normal 
  volumes, 
  we 
  have 
  the 
  following 
  relations 
  : 
  

  

  

  Formula. 
  

  

  

  Density. 
  

  

  

  

  Theoretical. 
  

  

  Observed. 
  

  

  I. 
  

  

  3J 
  An. 
  + 
  1 
  Al. 
  

  

  , 
  2.728 
  

  

  2.715 
  

  

  II. 
  

  

  3 
  An. 
  + 
  1 
  Al. 
  

  

  2.724 
  

  

  2.709 
  

  

  III. 
  

  

  24 
  An. 
  + 
  1 
  Al. 
  

  

  2.720 
  

  

  2.714 
  

  

  IV. 
  

  

  2 
  An. 
  + 
  1 
  Al. 
  

  

  2.713 
  

  

  2.709 
  

  

  V, 
  VI. 
  

  

  14 
  An. 
  + 
  1 
  Al. 
  

  

  2.704 
  

  

  2.705 
  and 
  2.729 
  

  

  VII, 
  VIII. 
  

  

  1 
  An. 
  + 
  1 
  Al. 
  

  

  2.691 
  

  

  2.68 
  and 
  2.697 
  

  

  The 
  lack 
  of 
  closer 
  agreement 
  between 
  the 
  theoretical 
  and 
  

   observed 
  density 
  may 
  be 
  due 
  to 
  lack 
  of 
  structural 
  homogeneity 
  

   or 
  continuity, 
  and 
  not 
  to 
  real 
  discrepancies. 
  

  

  The 
  above 
  theoretical 
  interpretation 
  of 
  the 
  results 
  of 
  these 
  

   labradorite 
  analyses, 
  is 
  founded 
  upon 
  a 
  certain 
  misconception 
  

   of 
  views 
  which 
  were 
  originally 
  advanced 
  by 
  Dr. 
  T. 
  Sterry 
  

   Hunt 
  so 
  long 
  since 
  as 
  September, 
  1853, 
  in 
  an 
  article 
  published 
  

   in 
  the 
  American 
  Journal 
  of 
  Science 
  of 
  that 
  date, 
  upon 
  "The 
  

   Constitution 
  and 
  Equivalent 
  Volume 
  of 
  Mineral 
  Species. 
  ' 
  ' 
  They 
  

  

  * 
  Quoted 
  from 
  Handb. 
  der 
  Mineralckemie, 
  Rammelsberg, 
  Vol. 
  II, 
  p. 
  562. 
  

  

  