﻿Notes 
  upon 
  the 
  Lithology 
  of 
  the 
  Adirondack^. 
  81 
  

  

  feldspar, 
  forming 
  a 
  granular 
  mass 
  quite 
  friable 
  in 
  its 
  texture, 
  

   and 
  of 
  a 
  dirty 
  grey 
  color. 
  It 
  is 
  generally 
  found 
  in 
  layers 
  in 
  

   the 
  veins 
  of 
  iron 
  ore, 
  or 
  in 
  the 
  vicinity 
  of 
  ore 
  beds 
  ; 
  it 
  often 
  

   forms, 
  also, 
  dykes 
  traversing 
  the 
  rock 
  in 
  the 
  manner 
  of 
  the 
  com- 
  

   mon 
  green-stone 
  trap, 
  as 
  may 
  be 
  seen 
  on 
  Mt. 
  McMartin, 
  by 
  

   Avalanche 
  Lake. 
  The 
  hypersthene 
  rock 
  also 
  contains 
  two 
  

   varieties 
  of 
  porphyry 
  : 
  1. 
  With 
  a 
  base 
  of 
  light 
  green 
  compact 
  

   feldspar, 
  spotted 
  with 
  small 
  masses 
  of 
  a 
  deep 
  bluish-green 
  feld- 
  

   spar. 
  2. 
  With 
  a 
  white 
  or 
  flesh-red 
  compact 
  base, 
  in 
  which 
  

   there 
  are 
  angular 
  masses 
  of 
  greenish 
  compact 
  feldspar. 
  Con- 
  

   nected 
  with 
  these 
  porphyries 
  is 
  prehnite, 
  in 
  mammillary 
  masses 
  

   of 
  a 
  pale 
  green 
  color, 
  with 
  a 
  few 
  indistinct 
  crystals. 
  

  

  " 
  The 
  porphyries 
  or 
  breccias, 
  which 
  have 
  been 
  found 
  mostly 
  

   in 
  loose 
  masses 
  upon 
  the 
  beaches 
  of 
  the 
  East 
  river, 
  are 
  undoubt- 
  

   edly 
  all 
  of 
  them 
  in 
  veins 
  like 
  the 
  ordinary 
  trap 
  of 
  this 
  region. 
  

   One 
  locality 
  is 
  known 
  on 
  this 
  river, 
  which 
  it 
  crosses 
  one 
  or 
  one 
  

   mile 
  and 
  a 
  half 
  below 
  the 
  Great 
  Falls. 
  It 
  is 
  an 
  extremely 
  

   tough 
  mass, 
  being 
  composed 
  of 
  chalcedony 
  and 
  feldspar, 
  and 
  a 
  

   decomposable 
  green 
  substance. 
  Rolled 
  masses 
  of 
  the 
  common 
  

   flesh-colored 
  feldspar 
  or 
  granite, 
  and 
  handsome 
  specimens 
  of 
  

   graphic 
  granite, 
  are 
  also 
  found. 
  A 
  variety 
  of 
  feldspar 
  is 
  not 
  

   unfrequent 
  in 
  veins 
  in 
  the 
  hypersthene, 
  which 
  resembles 
  albite 
  ; 
  

   and 
  it 
  seems 
  to 
  take 
  the 
  place 
  of 
  this 
  mineral, 
  or 
  to 
  hold 
  the 
  

   same 
  relation 
  to 
  the 
  hypersthene 
  rock 
  that 
  the 
  common 
  albite 
  

   does 
  to 
  the 
  coarse 
  granites 
  of 
  New 
  England. 
  It 
  is 
  in 
  laminated 
  

   and 
  stellar 
  masses, 
  like 
  the 
  albite 
  of 
  Chesterfield, 
  but 
  not 
  so 
  

   distinct, 
  or 
  handsome. 
  There 
  is 
  also 
  a 
  labradorite, 
  of 
  a 
  dark 
  

   bottle-green 
  color, 
  in 
  cleavage 
  masses, 
  two 
  or 
  three 
  inches 
  in 
  

   length, 
  with 
  striated 
  surfaces 
  and 
  more 
  feeble 
  opalescence 
  than 
  

   the 
  blue 
  variety. 
  This 
  rock, 
  above 
  Russell 
  Falls 
  on 
  the 
  Ausa- 
  

   ble, 
  passes 
  into 
  a 
  light 
  green 
  and 
  nearly 
  compact 
  feldspar. 
  

   When 
  wet, 
  it 
  is 
  a 
  pale 
  apple-green 
  ; 
  but 
  when 
  dry, 
  it 
  is 
  dull, 
  

   and 
  weathers 
  rapidly 
  into 
  a 
  putty 
  -like 
  clay." 
  

  

  It 
  will 
  be 
  seen 
  from 
  the 
  above 
  rather 
  full 
  abstract, 
  that 
  valu- 
  

   able 
  as 
  were 
  the 
  observations 
  of 
  Emmons, 
  but 
  little 
  was 
  done, 
  

   or 
  was 
  possible 
  at 
  that 
  time, 
  towards 
  forming 
  a 
  systematic 
  

   lithology 
  of 
  the 
  Adirondacks. 
  

  

  That 
  lithology 
  has 
  its 
  foundation 
  in 
  the 
  extensive 
  researches 
  of 
  

   Sir 
  Wm. 
  Logan, 
  Prof. 
  T. 
  S 
  terry 
  Hunt 
  and 
  their 
  colleagues 
  upon 
  

   the 
  azoic 
  formation 
  of 
  Canada, 
  and 
  many 
  valuable 
  contributions 
  

   6 
  

  

  