﻿Notes 
  upon 
  the 
  Lithology 
  of 
  the 
  Adikondacks. 
  89 
  

  

  crystals 
  imbedded 
  in 
  it. 
  Or 
  the 
  paste 
  may 
  be 
  granular 
  or 
  

   compact, 
  or 
  dirty- 
  white 
  or 
  light 
  or 
  dark-green 
  in 
  color. 
  Some- 
  

   times, 
  when 
  diallage 
  is 
  present, 
  it 
  may 
  be 
  segregated 
  into 
  

   minute 
  separate 
  masses, 
  or 
  distributed 
  through 
  the 
  paste, 
  may 
  

   communicate 
  to 
  it 
  a 
  color. 
  

  

  In 
  specimen 
  2, 
  almandite, 
  in 
  Nos. 
  19, 
  25 
  and 
  31, 
  diallage 
  and 
  

   hornblende 
  as 
  well, 
  are 
  present 
  in 
  these 
  porphyritic 
  norites, 
  

   the 
  garnets 
  being 
  in 
  these 
  cases 
  more 
  especially 
  associated 
  with 
  

   the 
  non-feldspathic 
  portion. 
  Garnet 
  is 
  not 
  unfrequently 
  dis 
  

   posed 
  as 
  a 
  red 
  border 
  around 
  the 
  greenish 
  masses 
  of 
  diallage, 
  

   along 
  the 
  bounding 
  surfaces] 
  between 
  it 
  and 
  the 
  labradorite. 
  

   The 
  included 
  crystals 
  are 
  sometimes 
  magnificently 
  opalescent, 
  

   as 
  in 
  No. 
  65 
  (a 
  specimen 
  not 
  tabulated), 
  which 
  was 
  obtained 
  

   from 
  a 
  large 
  boulder, 
  probably 
  derived 
  from 
  the 
  adjacent 
  

   mountain, 
  lying 
  in 
  the 
  Uba 
  trail. 
  When 
  opalescence 
  is 
  not 
  

   evident 
  upon 
  a 
  natural 
  or 
  fresh 
  fracture, 
  it 
  may 
  be 
  developed 
  

   by 
  grinding 
  and 
  polishing. 
  This 
  is 
  beautifully 
  shown 
  in 
  a 
  

   large 
  mass, 
  weighing 
  about 
  20 
  pounds, 
  brought 
  from 
  the 
  sum- 
  

   mit 
  of 
  Mt. 
  Marcy, 
  and 
  polished, 
  by 
  kindness 
  of 
  Mr. 
  John 
  

   Matthews, 
  at 
  his 
  manufactory 
  in 
  New 
  York. 
  It 
  is 
  of 
  a 
  mottled 
  

   smoky-grey 
  color, 
  opalescent 
  in 
  the 
  more 
  highly 
  crystalline 
  

   portions. 
  Unfortunately, 
  the 
  pyroxenic 
  ingredient 
  wears 
  away 
  

   irregularly 
  and 
  does 
  not 
  admit 
  of 
  polishing, 
  while 
  the 
  feldspar 
  

   is 
  opalescent 
  only 
  where 
  the 
  incident 
  light 
  falls 
  at 
  particular 
  

   angles 
  — 
  properties 
  which 
  must 
  seriously 
  militate 
  against 
  the 
  

   introduction 
  of 
  any, 
  but 
  the 
  most 
  homogeneous 
  of 
  these 
  por- 
  

   phyritic 
  norites, 
  as 
  an 
  ornamental 
  stone. 
  

  

  In 
  Nos. 
  30, 
  32, 
  33, 
  34, 
  35, 
  36 
  (see 
  its 
  microscopic 
  characters, 
  

   Part 
  IV) 
  and 
  41, 
  the 
  labradorite 
  is 
  represented 
  by 
  a 
  very 
  dark 
  

   green 
  variety. 
  It 
  appears 
  to 
  have 
  undergone 
  great 
  alteration, 
  

   having 
  lost 
  its 
  crystalline 
  character 
  and 
  become 
  translucent, 
  

   acquiring 
  at 
  the 
  same 
  time 
  a 
  greenish 
  color. 
  It 
  is 
  intermixed 
  

   with 
  much 
  finely- 
  granular 
  quartz, 
  visible 
  only 
  under 
  the 
  

   microscope. 
  With 
  these, 
  reddish-brown 
  hornblende 
  is 
  asso- 
  

   ciated, 
  having 
  been 
  derived 
  from 
  an 
  alteration 
  of 
  the 
  diallage 
  

   so 
  extensive, 
  that 
  the 
  latter 
  mineral 
  is 
  represented 
  only 
  by 
  

   some 
  scattered 
  green 
  particles, 
  invisible 
  to 
  the 
  naked 
  eye. 
  In 
  

   specimen 
  63, 
  the 
  pyroxene 
  is 
  not 
  foliated 
  or 
  bladed, 
  but 
  is 
  the 
  

   green 
  granular 
  variety 
  called 
  coccolite. 
  It 
  was 
  obtained 
  on 
  

   the 
  road 
  from 
  Lake 
  Placid 
  to 
  Wilmington. 
  

  

  