﻿GEOLOGY 
  OF 
  SARATOGA 
  SPRINGS 
  AND 
  VICINITY 
  23 
  

  

  through 
  the 
  surrounding 
  schists. 
  Except 
  for 
  being 
  usually 
  more 
  

   quartzose 
  they 
  are 
  quite 
  like 
  the 
  granite 
  in 
  mineralogy, 
  coarsely 
  

   crystalline 
  aggregates 
  of 
  quartz 
  and 
  white 
  feldspars 
  (microperthite 
  

   and 
  oligoclase) 
  with 
  some 
  biotite 
  and 
  often 
  garnets. 
  The 
  schists 
  

   just 
  to 
  the 
  north 
  of 
  Saratoga, 
  as. 
  shown 
  along 
  the 
  Adirondack 
  Rail- 
  

   road 
  and 
  along 
  the 
  north 
  margin 
  of 
  Highland 
  park, 
  are 
  full 
  of 
  

   these 
  dikes 
  ; 
  and 
  a 
  little 
  farther 
  north, 
  along 
  the 
  fault 
  scarp, 
  the 
  

   granite 
  shows 
  well 
  and 
  accessibly 
  and 
  has 
  been 
  quarried 
  somewhat. 
  

   In 
  addition 
  to 
  the 
  usual 
  minerals 
  these 
  dikes 
  show 
  here 
  and 
  there 
  

   other 
  and 
  rarer 
  minerals. 
  The 
  old 
  chrysoberyl 
  locality, 
  just 
  to 
  the 
  

   north 
  of 
  Saratoga, 
  is 
  on 
  one 
  of 
  these 
  dikes 
  in 
  the 
  schist. 
  In 
  this 
  

   a 
  lot 
  of 
  black 
  tourmaline 
  has 
  developed, 
  so 
  that 
  the 
  pegmatite 
  is 
  a 
  

   quartz-feldspar-tourmaline-garnet 
  rock, 
  in 
  which 
  frequent 
  nests 
  of 
  

   chrysoberyl 
  crystals 
  occur. 
  The 
  dike 
  cuts 
  a 
  hard 
  mica 
  gneiss 
  and 
  is 
  

   about 
  3 
  feet 
  wide 
  at 
  the 
  old 
  pit. 
  One 
  and 
  one-half 
  miles 
  south 
  

   of 
  South 
  Corinth 
  is 
  another 
  old 
  mineral 
  pit 
  on 
  a 
  pegmatite 
  vein 
  in 
  

   schists, 
  which 
  furnished 
  fine 
  black 
  tourmaline 
  and 
  rose 
  quartz. 
  

  

  Mixed 
  rock. 
  With 
  the 
  exception 
  of 
  the 
  pegmatites 
  practically 
  all 
  

   the 
  granite 
  is 
  contaminated 
  with 
  schist. 
  We 
  interpret 
  this 
  con- 
  

   tamination 
  as 
  resulting 
  from 
  the 
  shredding 
  and 
  dispersion 
  of 
  the 
  

   schist 
  inclusions 
  in 
  the 
  granite 
  under 
  conditions 
  of 
  extreme 
  pressure 
  

   and 
  metamorphism. 
  All 
  gradations 
  occur 
  between 
  bands 
  of 
  schist 
  

   somewhat 
  impregnated 
  by 
  granite 
  and 
  granite 
  that 
  seems 
  normal 
  

   except 
  for 
  the 
  fact 
  that 
  it 
  may 
  be 
  somewhat 
  more 
  micaceous 
  than 
  

   it 
  should 
  be. 
  This 
  introduces 
  an 
  element 
  of 
  uncertainty 
  in 
  the 
  

   attempt 
  to 
  investigate 
  the 
  granite 
  chemically. 
  

  

  Chemical 
  composition. 
  The 
  material 
  chosen 
  for 
  analysis 
  was 
  

   obtained 
  from 
  the 
  quarry 
  in 
  the 
  granite 
  on 
  the 
  face 
  of 
  the 
  fault 
  

   scarp 
  2 
  miles 
  north 
  of 
  Saratoga, 
  and 
  was 
  chosen 
  because 
  it 
  was 
  

   fresh 
  and 
  because 
  contamination 
  with 
  schist 
  seemed 
  slight, 
  if 
  any. 
  

   The 
  thin 
  section 
  showed 
  quartz, 
  about 
  25 
  per 
  cent, 
  feldspars 
  about 
  

   equally 
  divided 
  between 
  oligoclase 
  on 
  the 
  one 
  hand 
  and 
  microcline 
  

   and 
  microperthite 
  on 
  the 
  other, 
  about 
  70 
  per 
  cent, 
  and 
  the 
  remainder 
  

   biotite, 
  except 
  for 
  a 
  few 
  small 
  zircons 
  and 
  a 
  trirle 
  of 
  apatite 
  and 
  

   titanite. 
  The 
  hand 
  specimen 
  shows 
  occasional 
  garnets, 
  none 
  of 
  

   which 
  got 
  into 
  the 
  thin 
  section. 
  The 
  rock 
  shows 
  a 
  rude 
  banding 
  due 
  

   to 
  variations 
  in 
  the 
  amount 
  of 
  mica*, 
  suggesting 
  a 
  trifle 
  of 
  shredded 
  

   schist 
  in 
  the 
  more 
  micaceous 
  bands, 
  but 
  not 
  enough 
  to 
  impair 
  

   materially 
  the 
  value 
  of 
  Doctor 
  Morley's 
  analysis. 
  

  

  