﻿62 
  L. 
  V. 
  Pirsson 
  — 
  Gmelinite 
  from 
  Nova 
  Scotia. 
  

  

  Our 
  theory 
  demands 
  for 
  ?a^r, 
  1010 
  a 
  1011, 
  of 
  gmelinite 
  

   49° 
  42'. 
  In 
  two 
  cases 
  the 
  above 
  were 
  measured 
  both 
  as 
  posi- 
  

   tive 
  and 
  negative 
  rhombohedron 
  on 
  the 
  same 
  fragment. 
  This 
  

   latter 
  and 
  the 
  fact 
  that 
  the 
  crystals 
  are 
  more 
  or 
  less 
  cellular 
  

   internally, 
  renders 
  it 
  probable 
  that 
  these 
  reflections 
  came 
  from 
  

   minute 
  interior 
  faces. 
  

  

  Chemical 
  composition. 
  — 
  In 
  order 
  to 
  obtain 
  a 
  control 
  over 
  

   the 
  crystallographic 
  work 
  on 
  the 
  Five 
  Islands 
  gmelinite, 
  two 
  

   analyses 
  A 
  and 
  B 
  have 
  been 
  made. 
  In 
  A, 
  the 
  outer 
  shell 
  men- 
  

   tioned 
  before, 
  was 
  analyzed, 
  and 
  in 
  B 
  the 
  inner 
  nucleus. 
  The 
  

   material 
  was 
  easily 
  obtained 
  by 
  taking 
  fine 
  crystals 
  and 
  split- 
  

   ting 
  off 
  the 
  shell 
  by 
  pressure. 
  The 
  fragments 
  thus 
  obtained 
  

   were 
  perfectly 
  colorless, 
  the 
  inner 
  portion 
  had 
  the 
  usual 
  flesh 
  

   color. 
  Both 
  ground 
  to 
  a 
  pure 
  white 
  powder. 
  The 
  analyses 
  on 
  

   the 
  air-dried 
  material 
  were 
  as 
  follows 
  : 
  

  

  Si0 
  2 
  

  

  A1 
  2 
  3 
  

  

  A 
  

  

  .. 
  50-35 
  

  

  18-33 
  

  

  B 
  

  

  50-67 
  

   18-50 
  

  

  Fe 
  2 
  3 
  . 
  

  

  ._ 
  0-26 
  

  

  0-15 
  

  

  CaO 
  

  

  K 
  2 
  .._ 
  

  

  101 
  

  

  0-15 
  

  

  1-05 
  

   0-16 
  

  

  Na 
  2 
  

  

  H 
  2 
  

  

  9-76 
  

  

  20-23 
  

  

  988 
  

   20-15 
  

  

  

  

  

  100-09 
  100-56 
  

  

  It 
  will 
  be 
  observed 
  that 
  the 
  analyses 
  show 
  no 
  difference 
  be- 
  

   tween 
  the 
  two 
  portions. 
  Also 
  the 
  specific 
  gravity 
  carefully 
  

   taken 
  with 
  the 
  heavy 
  solution 
  was 
  found 
  to 
  be 
  2 
  037, 
  the 
  same 
  

   for 
  both. 
  The 
  most 
  marked 
  result 
  of 
  the 
  analyses 
  is 
  the 
  very 
  

   small 
  amount 
  of 
  lime 
  and 
  large 
  amount 
  of 
  soda 
  indicated. 
  

  

  Analyses 
  of 
  American 
  gmelinite, 
  on 
  material 
  from 
  Two 
  

   Islands, 
  Five 
  Islands 
  and 
  Bergen 
  Hill 
  have 
  been 
  made 
  by 
  A. 
  

   B. 
  Howe.* 
  It 
  will 
  be 
  observed 
  that 
  the 
  one 
  on 
  Five 
  Islands' 
  

   material 
  is 
  almost 
  exactly 
  like 
  those 
  just 
  given. 
  

  

  Two 
  Bergen 
  Five 
  

  

  Islands 
  f. 
  Theory. 
  Hills 
  {. 
  Theory. 
  Islands 
  f. 
  Theory. 
  

  

  Si0 
  2 
  51-36 
  51-18 
  48 
  67 
  48-79 
  50-45 
  49 
  

  

  A1 
  2 
  3 
  17 
  81 
  17-42 
  1872 
  18-84 
  18'27 
  18 
  

  

  Fe 
  2 
  3 
  0-15 
  0-10 
  0-17 
  

  

  CaO 
  5-68 
  6-04 
  2-60 
  2'40 
  112 
  

  

  K 
  2 
  0-23 
  trace 
  0-20 
  

  

  Na 
  2 
  3-92 
  3*89 
  914 
  8"69 
  9'79 
  9' 
  

  

  n 
  2 
  2096 
  2147 
  21-35 
  21-28 
  20-71 
  21 
  

  

  100-11 
  100-00 
  100-58 
  100-00 
  100 
  71 
  100-00 
  

  

  In 
  the 
  article 
  previously 
  quoted 
  IStreng 
  has 
  shown 
  that 
  chaba- 
  

   zite 
  may 
  be 
  considered 
  a 
  mixture 
  of 
  two 
  isomorphous 
  hydrated 
  

   molecules, 
  similar 
  to 
  the 
  feldspars. 
  If 
  we 
  consider 
  gmelinite 
  

   as 
  a 
  soda 
  chabazite, 
  we 
  then 
  have 
  for 
  these 
  molecules 
  : 
  

  

  oj 
  = 
  NaAlSi 
  B 
  8 
  . 
  4ll 
  2 
  y=Na 
  2 
  Al 
  2 
  Si 
  2 
  8 
  . 
  4H 
  2 
  

   * 
  This 
  Jour., 
  vol. 
  xii, 
  pp. 
  270, 
  1876. 
  

  

  