﻿L. 
  V. 
  Pirsson 
  — 
  Gmelinite 
  from 
  Nova 
  Scotia. 
  57 
  

  

  Art. 
  YIII. 
  — 
  Gmelinite 
  from 
  Nova 
  Scotia; 
  by 
  Louis 
  V. 
  

   Pirsson. 
  

  

  The 
  zeolites 
  of 
  Nova 
  Scotia 
  have 
  long 
  been 
  noted 
  for 
  the 
  

   size 
  and 
  perfection 
  of 
  their 
  crystals, 
  and 
  among 
  them 
  gmelinite 
  

   has 
  held 
  a 
  prominent 
  place. 
  Originally 
  described 
  by 
  Jackson* 
  

   under. 
  the 
  name 
  of 
  ledererite, 
  it 
  was 
  first 
  proved 
  to 
  be 
  identical 
  

   with 
  the 
  gmelinite 
  of 
  European 
  localities 
  by 
  Des 
  Cloizeaux,f 
  

   from 
  crystallographic 
  measurements. 
  This 
  was 
  subsequently 
  

   confirmed 
  by 
  analyses 
  published 
  by 
  Marsh. 
  \ 
  Analyses 
  have 
  

   also 
  been 
  published 
  by 
  A. 
  B. 
  Howe, 
  referred 
  to 
  later. 
  Beyond 
  

   these 
  observations 
  there 
  seems 
  to 
  have 
  been 
  no 
  investigation 
  of 
  

   the 
  crystal 
  form 
  and 
  physical 
  properties 
  of 
  the 
  mineral 
  from 
  

   American 
  localities. 
  This 
  has 
  been 
  undertaken 
  chiefly 
  upon 
  

   material 
  collected 
  during 
  the 
  past 
  summer 
  at 
  Pinnacle* 
  Island, 
  

   one 
  of 
  the 
  " 
  Five 
  Islands" 
  in 
  the 
  Basin 
  of 
  Minas, 
  JN~ova 
  Scotia. 
  

   An 
  analysis, 
  which 
  was 
  made 
  to 
  control 
  the 
  results 
  of 
  the 
  inves- 
  

   tigation, 
  having 
  brought 
  out 
  some 
  interesting 
  facts, 
  a 
  discus- 
  

   sion 
  of 
  the 
  chemical 
  composition 
  has 
  also 
  been 
  added. 
  And 
  

   since 
  gmelinite 
  has 
  been 
  referred 
  by 
  some 
  authors, 
  especially 
  

   Tamnau§ 
  and 
  StrengJ 
  to 
  chabazite, 
  all 
  points 
  bearing 
  on 
  this 
  

   question 
  have 
  been 
  kept 
  in 
  mind 
  and 
  are 
  here 
  presented. 
  

  

  The 
  gmelinite 
  from 
  Five 
  Islands 
  occurs 
  in 
  seams 
  implanted 
  

   in 
  a 
  greatly 
  decomposed 
  trap. 
  The 
  crystals, 
  often 
  of 
  large 
  size, 
  

   vary 
  in 
  color 
  from 
  a 
  very 
  pale 
  flesh-red 
  to 
  a 
  strong 
  reddish- 
  

   brown. 
  In 
  thin 
  section 
  they 
  are 
  seen 
  to 
  be 
  composed 
  of 
  a 
  

   colorless 
  outer 
  shell 
  or 
  zone, 
  inclosing 
  a 
  colored 
  inner 
  nucleus. 
  

   In 
  grinding 
  the 
  sections 
  it 
  was 
  noticed 
  that 
  the 
  outer 
  shell 
  was 
  

   hard 
  and 
  tough, 
  preserving 
  the 
  crystal 
  boundaries, 
  while 
  the 
  

   inner 
  portion 
  was 
  spongy, 
  cellular, 
  somewhat 
  friable 
  and 
  

   readily 
  crumbled 
  away. 
  In 
  large 
  crystals 
  the 
  separation 
  into 
  

   parts 
  of 
  the 
  colorless 
  outer 
  shell 
  and 
  the 
  colored 
  nucleus 
  can 
  

   be 
  readily 
  seen 
  with 
  the 
  eye 
  at 
  a 
  trihedral 
  angle. 
  There 
  were 
  

   no 
  inclusions 
  seen 
  in 
  thin 
  section, 
  only 
  a 
  slight 
  discoloration 
  

   along 
  the 
  cleavage 
  cracks 
  and 
  occasionally 
  elsewhere. 
  The 
  

   crystals 
  from 
  Two 
  Islands, 
  ISTova 
  Scotia, 
  and 
  Bergen 
  Hill, 
  1ST. 
  J., 
  

   studied 
  in 
  connection 
  with 
  these 
  are 
  white, 
  often 
  with 
  a 
  pink 
  

   tinge, 
  translucent 
  and 
  apparently 
  entirely 
  homogeneous. 
  Some 
  

   in 
  Professor 
  Brush's 
  collection 
  labeled 
  Parsborough, 
  Nova 
  

   Scotia, 
  are 
  similar 
  to 
  those 
  from 
  Five 
  Islands 
  and 
  may 
  indeed 
  

   have 
  come 
  from 
  that 
  locality. 
  

  

  * 
  This 
  Jour., 
  xxv. 
  pp. 
  78, 
  1834. 
  f 
  Man. 
  de 
  Min.. 
  pp. 
  398, 
  1862. 
  

  

  % 
  This 
  Jour., 
  xliv, 
  pp. 
  362, 
  1867. 
  § 
  Jahrb. 
  f. 
  Min., 
  pp. 
  633, 
  1836. 
  

  

  || 
  Ber. 
  d. 
  Oberhess. 
  Ges. 
  f. 
  Natur 
  u. 
  Heilkunde, 
  xvi, 
  pp. 
  74, 
  1877; 
  also 
  full 
  

   abstract 
  in 
  Zeitschr. 
  f. 
  Kryst., 
  pp. 
  519, 
  vol. 
  i. 
  1877. 
  

  

  