﻿141 
  

  

  The 
  following 
  are 
  the 
  results 
  of 
  an 
  analysis 
  of 
  this 
  mineral 
  by 
  M. 
  

   Damour: 
  Silica, 
  59-64; 
  alumina, 
  16.33; 
  lime, 
  7-44; 
  soda, 
  1-16: 
  

   potash, 
  0-74; 
  water, 
  14-33. 
  This 
  composition 
  indicates 
  that 
  heulan- 
  

   dite 
  should 
  be 
  ranked 
  with 
  the 
  zeolites. 
  Philosophical 
  Mag. 
  and 
  Ann., 
  

   xxix., 
  p. 
  556. 
  

  

  It 
  seems 
  to 
  be 
  now 
  settled, 
  that 
  the 
  Lincolnite 
  of 
  Prof. 
  Hitchcock, 
  

   (Final 
  Report 
  on 
  the 
  Geological 
  Survey 
  of 
  Massachusetts, 
  p. 
  662,) 
  is 
  

   identical 
  with 
  heulandite. 
  Crystals, 
  exactly 
  like 
  those 
  described 
  by 
  

   Hitchcock, 
  have 
  been 
  found 
  in 
  gneiss 
  on 
  New- 
  York 
  Island. 
  Alger, 
  in 
  

   Sill. 
  Jour., 
  xlvi., 
  p. 
  235. 
  

  

  (Mineralogy 
  of 
  New- 
  York, 
  page 
  349.) 
  

   Since 
  the 
  publication 
  of 
  the 
  Mineralogy, 
  this 
  mineral 
  has 
  been 
  found 
  

   in 
  the 
  fissures 
  of 
  gneiss 
  in 
  23d 
  street, 
  New-York. 
  Dr. 
  Emmons 
  also 
  

   reports 
  localities 
  near 
  Adirondack, 
  and 
  in 
  Keene, 
  Essex 
  county. 
  Rep. 
  

   on 
  the 
  Geol. 
  2d 
  Dist., 
  p. 
  31. 
  

  

  LAUMONITE. 
  

   (Mineralogy 
  of 
  New- 
  York, 
  page 
  351.) 
  

  

  It 
  is 
  well 
  known 
  that 
  this 
  mineral 
  when 
  exposed 
  to 
  the 
  atmosphere, 
  soon 
  

   loses 
  its 
  transparency, 
  and 
  becomes 
  so 
  soft 
  as 
  to 
  yield 
  to 
  the 
  finger 
  nail. 
  

   According 
  to 
  M. 
  M. 
  Malaguti 
  and 
  Durocher, 
  this 
  efflorescence 
  is 
  owing 
  

   to 
  the 
  loss 
  of 
  a 
  small 
  quantity 
  of 
  water. 
  Specimens 
  of 
  it 
  did 
  not 
  suffer 
  

   the 
  least 
  alteration 
  when 
  kept 
  for 
  several 
  months 
  in 
  a 
  moist 
  amosphere. 
  

   Crystals 
  of 
  laumonite 
  altered, 
  recovered 
  their 
  original 
  transparency 
  and 
  

   appearance 
  by 
  being 
  immersed 
  in 
  water, 
  and 
  these 
  same 
  crystals, 
  after 
  

   drying 
  and 
  exposure 
  to 
  dry 
  air, 
  behaved 
  like 
  crystals 
  recently 
  taken 
  from 
  

   their 
  locality. 
  Phil. 
  Mag. 
  and 
  jfnn. 
  xxix, 
  p. 
  555. 
  

  

  Dana 
  states 
  that 
  the 
  rapid 
  decomposition 
  to 
  which 
  this 
  mineral 
  is 
  

   liable 
  may 
  be 
  prevented 
  by 
  dipping 
  the 
  specimen 
  in 
  a 
  thin 
  solution 
  of 
  

   gum 
  arabic, 
  by 
  means 
  of 
  which 
  it 
  is 
  preserved 
  from 
  contact 
  with 
  the 
  

   air. 
  Mineralogy, 
  2d 
  ed.. 
  p. 
  326. 
  

  

  