﻿82 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  into 
  a 
  basic 
  (quartzless) 
  syenite 
  which 
  contains 
  garnet 
  crystals 
  up 
  

   to 
  an 
  inch 
  or 
  more 
  across 
  but 
  never 
  with 
  hornblende 
  rims, 
  and 
  

   this 
  rock 
  in 
  turn 
  grades 
  into 
  the 
  typical 
  country 
  rock 
  of 
  syenite 
  

   which 
  is 
  somewhat 
  garnetiferous. 
  The 
  writer 
  is 
  fully 
  convinced 
  

   that 
  this 
  transition 
  zone 
  (wall 
  rock) 
  has 
  been 
  formed 
  by 
  the 
  as- 
  

   similation 
  or 
  actual 
  melting 
  or 
  fusing 
  together 
  of 
  the 
  syenite 
  and 
  the 
  

   border 
  of 
  the 
  great 
  inclusion 
  at 
  the 
  time 
  of 
  the 
  intrusion 
  of 
  the 
  

   syenite. 
  In 
  hand 
  specimens 
  and 
  in 
  thin 
  sections, 
  as 
  shown 
  in 
  the 
  

   field, 
  the 
  garnet 
  rock 
  at 
  the 
  Hooper 
  mine 
  is 
  almost 
  exactly 
  like 
  this 
  

   wall 
  or 
  transition 
  rock 
  of 
  the 
  Rogers 
  mine 
  and 
  it 
  also 
  appears 
  to 
  

   grade 
  into 
  the 
  country 
  rock. 
  In 
  the 
  Hooper 
  mine 
  this 
  transition 
  

   rock 
  makes 
  up 
  practically 
  the 
  whole 
  mass 
  of 
  rock 
  which 
  is 
  mined 
  

   and 
  is 
  hence 
  much 
  more 
  extensive 
  than 
  at 
  the 
  Rogers 
  mine. 
  All 
  

   evidence 
  strongly 
  points 
  to 
  the 
  origin 
  of 
  the 
  Hooper 
  mine 
  rock 
  as 
  

   due 
  to 
  rather 
  thorough 
  melting 
  together 
  of 
  an 
  admixture 
  of 
  syenite 
  

   and 
  Grenville 
  hornblende 
  gneiss 
  where 
  the 
  Grenville 
  inclusion 
  was 
  

   perhaps 
  deeper 
  down 
  in 
  the 
  magma 
  and 
  hence 
  subjected 
  to 
  much 
  

   greater 
  heat, 
  or 
  possibly 
  a 
  number 
  of 
  smaller 
  hornblende 
  gneiss 
  

   inclusions 
  were 
  assimilated 
  by 
  the 
  molten 
  syenite 
  or 
  granite. 
  

  

  GRAPHITE 
  

  

  Within 
  the 
  map 
  limits 
  but 
  one 
  graphite 
  mine 
  has 
  ever 
  been 
  in 
  

   actual 
  operation, 
  though 
  prospect 
  holes 
  have 
  been 
  made 
  at 
  various 
  

   places. 
  The 
  mine, 
  including 
  an 
  open 
  pit 
  and 
  short 
  tunnel 
  and 
  

   separating 
  mill, 
  is 
  located 
  I 
  mile 
  southwest 
  of 
  Johnsburg. 
  The 
  

   graphite 
  occurs 
  in 
  small 
  flakes 
  in 
  gray, 
  thin 
  to 
  thick 
  bedded, 
  Gren- 
  

   ville 
  gneisses 
  which 
  are 
  usually 
  very 
  rich 
  in 
  quartz. 
  A 
  detailed 
  

   description 
  of 
  specimens 
  from 
  this 
  mine 
  has 
  been 
  given 
  on 
  page 
  14. 
  

   Some 
  graphitic 
  limestone 
  was 
  taken 
  out 
  from 
  near 
  the 
  mine 
  en- 
  

   trance. 
  The 
  rocks 
  strike 
  north 
  70 
  ° 
  east 
  and 
  dip 
  35 
  ° 
  to 
  the 
  south. 
  

   This 
  mine 
  was 
  worked 
  as 
  late 
  as 
  June 
  1910 
  but 
  apparently 
  has 
  not 
  

   been 
  very 
  successful. 
  An 
  interesting 
  feature 
  is 
  a 
  quartz 
  vein 
  up 
  

   to 
  a 
  foot 
  wide, 
  which 
  cuts 
  across 
  the 
  graphitic 
  beds 
  at 
  a 
  high 
  angle 
  

   and 
  which 
  contains 
  rich 
  seams 
  (as 
  much 
  as 
  an 
  inch 
  wide) 
  of 
  pure 
  

   graphite. 
  The 
  mine 
  superintendent 
  stated 
  that 
  in 
  1899 
  one 
  piece 
  

   of 
  graphite 
  weighing 
  543 
  pounds 
  was 
  taken 
  out. 
  Excellent 
  speci- 
  

   mens 
  of 
  associated 
  quartz 
  and 
  graphite 
  may 
  be 
  obtained 
  from 
  the 
  

   mine 
  dumps. 
  

  

  A 
  prospect 
  hole 
  2^ 
  miles 
  due 
  south 
  of 
  Pottersville 
  and 
  close 
  

   to 
  the 
  road 
  was 
  opened 
  in 
  limestone 
  some 
  years 
  ago. 
  Some 
  of 
  

   the 
  limestone 
  beds 
  are 
  pyroxenic 
  to 
  serpentinous. 
  The 
  limestone 
  

   contains 
  occasional 
  flakes 
  of 
  graphite 
  up 
  to 
  one-half 
  of 
  an 
  inch 
  

  

  