﻿Notes 
  upon 
  the 
  Lithology 
  of 
  the 
  Adirondack^. 
  105 
  

  

  found 
  in 
  it. 
  The 
  feldspar 
  is 
  filled 
  throughout 
  with 
  excessively 
  

   minute 
  objects 
  of 
  the 
  same 
  nature 
  as 
  the 
  larger 
  objects. 
  

  

  The 
  gray 
  or 
  dark 
  color 
  of 
  the 
  plagioclase, 
  has 
  been 
  attributed 
  

   to 
  similar 
  inclusions 
  occurring 
  in 
  vast 
  numbers. 
  In 
  part, 
  they 
  

   are 
  fine 
  black 
  needles, 
  usually 
  of 
  equal 
  thickness, 
  and 
  in 
  length 
  

   at 
  times 
  as 
  much 
  as 
  0.14 
  m.m., 
  now 
  and 
  then 
  with 
  acute 
  termi- 
  

   nations. 
  They 
  mostly 
  lie 
  in 
  definite 
  directions. 
  There 
  are 
  

   besides, 
  minute 
  point-like 
  grains, 
  probably 
  the 
  black 
  needles 
  

   in 
  section. 
  In 
  extremely 
  thin 
  slices, 
  clear 
  brown 
  translucent 
  

   lamellae, 
  at 
  times 
  rounded, 
  at 
  times 
  six-sided, 
  make 
  their 
  

   appearance. 
  A 
  long 
  needle 
  or 
  lamella 
  is 
  often 
  composed 
  of 
  

   many 
  pieces. 
  They 
  are 
  placed 
  closely 
  one 
  after 
  another, 
  the 
  

   indented 
  terminations 
  mutually 
  interpenetrating. 
  Frequently, 
  

   there 
  are 
  found 
  light 
  green 
  bodies, 
  irregularly 
  arranged 
  and 
  in 
  

   smaller 
  quantities, 
  with 
  rounded 
  and 
  somewhat 
  elongated 
  sides. 
  

   They 
  are 
  probably 
  hornblende, 
  exhibiting 
  sometimes 
  an 
  angle 
  

   of 
  120°. 
  Generally, 
  they 
  are 
  associated 
  with 
  black 
  particles 
  of 
  

   magnetite. 
  The 
  inclusions 
  are 
  usually 
  met 
  with 
  in 
  the 
  central 
  

   portion 
  of 
  the 
  individual 
  feldspathic 
  masses. 
  Their 
  edges 
  are 
  

   ordinarily 
  quite 
  free 
  from 
  them, 
  appearing 
  pure 
  and 
  limpid. 
  

   Such 
  is 
  the 
  plagioclase 
  of 
  the 
  norite 
  of 
  Krageroe, 
  which 
  while 
  

   black 
  in 
  mass, 
  is 
  reddish-brown 
  in 
  sections 
  on 
  account 
  of 
  the 
  

   myriads 
  of 
  yellowish 
  or 
  brownish 
  grains 
  and 
  needles. 
  

  

  The 
  larger 
  six-sided 
  crystals 
  occurring 
  in 
  the 
  labradorite 
  of 
  

   Hitteroe 
  in 
  Norway, 
  sometimes 
  with 
  reddish 
  or 
  reddish-yellow 
  

   translucency, 
  Scheerer 
  regarded 
  as 
  specular 
  iron. 
  All 
  the 
  

   remainder, 
  with 
  few 
  exceptions, 
  are 
  quite 
  opaque 
  and 
  black. 
  

   Most 
  probably 
  they 
  are 
  not 
  specular 
  iron 
  but 
  menaccanite, 
  a 
  sup- 
  

   position 
  borne 
  out 
  by 
  the 
  customary 
  occurrence 
  of 
  menaccanite 
  

   in 
  the 
  labradorite 
  of 
  Hitteroe. 
  Besides 
  these, 
  some 
  transparent 
  

   plates 
  were 
  observed 
  by 
  Scheerer, 
  in 
  part 
  brown, 
  in 
  part 
  green, 
  

   which 
  appeared 
  to 
  form 
  many-sided 
  prisms, 
  with 
  replacements 
  

   at 
  both 
  terminations. 
  (They 
  may 
  have 
  been 
  pyroxene 
  in 
  part 
  

   altered 
  to 
  hornblende.) 
  

  

  20. 
  The 
  labradorite, 
  together 
  with 
  some 
  quartz, 
  is 
  quite 
  trans- 
  

   parent 
  and 
  clear. 
  It 
  is 
  traversed 
  by 
  masses 
  of 
  a 
  dark 
  intensely- 
  

   green 
  pyroxenic 
  ingredient, 
  which 
  are 
  arranged 
  with 
  a 
  certain 
  

   approach 
  to 
  parallelism. 
  They 
  are 
  cut 
  up 
  by 
  distinct 
  fine 
  lines, 
  

   also 
  approximately 
  parallel 
  to 
  one 
  another, 
  which 
  impart 
  a 
  

   fibrous 
  appearance. 
  In 
  part 
  they 
  are 
  feebly 
  dichroic, 
  as 
  if 
  

  

  