﻿GEOLOGY 
  OF 
  THE 
  NORTH 
  CREEK 
  QUADRANGLE 
  83 
  

  

  across, 
  as 
  well 
  as 
  some 
  phlogopite, 
  pyrite, 
  brown 
  hornblende, 
  and 
  a 
  

   few 
  octahedrons 
  of 
  brown 
  spinel. 
  

  

  One-half 
  of 
  a 
  mile 
  beyond 
  the 
  northern 
  map 
  limit 
  and 
  near 
  where 
  

   the 
  road 
  crosses 
  Trout 
  brook 
  there 
  is 
  an 
  old 
  graphite 
  mine 
  which 
  

   was 
  not 
  visited 
  by 
  the 
  writer. 
  

  

  Throughout 
  the 
  quadrangle 
  scattering 
  flakes 
  of 
  graphite 
  are 
  

   rarely 
  absent 
  from 
  the 
  crystalline 
  limestone, 
  and 
  more 
  seldom 
  they 
  

   are 
  found 
  in 
  other 
  rocks 
  of 
  the 
  sedimentary 
  series. 
  

  

  MICA 
  

  

  The 
  only 
  place 
  where 
  mica 
  mining 
  has 
  been 
  attempted 
  is 
  in 
  a 
  

   large 
  pegmatite 
  dike, 
  which 
  comes 
  against 
  the 
  long 
  gabbro 
  mass 
  

   on 
  its 
  east 
  side, 
  2^ 
  miles 
  south-southeast 
  of 
  Chestertown. 
  At 
  the 
  

   time 
  of 
  the 
  writer's 
  visit 
  (1910) 
  the 
  mine 
  was 
  being 
  worked 
  in 
  a 
  

   small 
  way 
  by 
  two 
  or 
  three 
  men. 
  While 
  occasionally 
  mica 
  is 
  present 
  

   in 
  considerable 
  quantity, 
  it 
  seldom 
  occurs 
  in 
  books 
  up 
  to 
  5 
  or 
  6 
  

   inches 
  across. 
  Muscovite 
  mica 
  is 
  often 
  associated 
  with 
  the 
  peg- 
  

   matite 
  dikes 
  but 
  thus 
  far 
  no 
  place 
  has 
  been 
  discovered 
  which 
  

   could 
  really 
  be 
  called 
  a 
  good 
  mining 
  proposition. 
  

  

  ASBESTOS 
  

  

  The 
  only 
  attempt 
  to 
  mine 
  asbestos 
  is 
  at 
  the 
  locality 
  three-fourths 
  

   of 
  a 
  mile 
  southeast 
  of 
  Thurman 
  village. 
  During 
  the 
  summer 
  of 
  

   1910 
  large 
  prospect 
  holes 
  had 
  been 
  opened 
  up 
  and 
  mining 
  machinery 
  

   was 
  being 
  installed, 
  though 
  the 
  writer 
  does 
  not 
  know 
  whether 
  the 
  

   mine 
  is 
  now 
  in 
  operation. 
  The 
  asbestos 
  is 
  of 
  the 
  serpentine 
  variety, 
  

   known 
  as 
  chrysotile, 
  and 
  occurs 
  in 
  numerous 
  irregular 
  veins 
  in 
  the 
  

   greenish 
  gray 
  serpentine 
  marble. 
  Of 
  all 
  the 
  veins 
  noted 
  in 
  the 
  

   prospect 
  holes, 
  the 
  widest 
  was 
  less 
  than 
  an 
  inch, 
  though 
  wider 
  veins 
  

   may 
  since 
  have 
  been 
  found. 
  The 
  asbestos 
  is 
  of 
  good 
  quality, 
  but 
  

   numerous 
  fairly 
  thick 
  veins 
  must 
  be 
  found 
  in 
  order 
  to 
  make 
  a 
  

   paying 
  proposition 
  of 
  the 
  mine. 
  

  

  FELDSPAR 
  

  

  Orthoclase 
  feldspar 
  is 
  of 
  course 
  one 
  of 
  the 
  commonest 
  minerals 
  

   in 
  the 
  whole 
  region, 
  but 
  only 
  where 
  it 
  occurs 
  in 
  large 
  crystals 
  in 
  

   the 
  pegmatite 
  dikes 
  is 
  it 
  likely 
  ever 
  to 
  become 
  of 
  commercial 
  im- 
  

   portance. 
  In 
  all 
  the 
  numerous 
  pegmatite 
  dikes 
  examined, 
  the 
  

   orthoclase 
  almost 
  invariably 
  occurs 
  in 
  crystals 
  which 
  are 
  too 
  small 
  

   and 
  too 
  intimately 
  associated 
  with 
  much 
  quartz 
  and 
  acid 
  plagioclase 
  

   feldspar 
  to 
  be 
  worth 
  considering 
  as 
  mining 
  propositions. 
  • 
  Perhaps 
  

  

  