﻿92 
  TWENTY-FIRST 
  REPORT 
  ON 
  THE 
  STATE 
  CABINET. 
  

  

  "with 
  beds 
  of 
  silicious 
  rock 
  impregnated 
  with 
  plumbago 
  from 
  more 
  

   than 
  one 
  locality.] 
  

  

  Graphite 
  or 
  Plumbago. 
  — 
  This 
  mineral 
  is 
  occasionally 
  met 
  with 
  

   in 
  most 
  of 
  the 
  stratified 
  rocks 
  of 
  the 
  Laurentian 
  system 
  j 
  not 
  only 
  

   the 
  limestones, 
  but 
  the 
  gneiss, 
  pyroxenite, 
  quartzite 
  and 
  pyrallolite 
  

   beds 
  sometimes 
  hold 
  disseminated 
  graphite. 
  It 
  is 
  moreover 
  met 
  

   with 
  in 
  the 
  iron 
  ores 
  of 
  the 
  series, 
  as 
  in 
  Hull, 
  Quebec, 
  where 
  large 
  

   scales 
  of 
  graphite 
  are 
  imbedded 
  in 
  the 
  crystalline 
  magnetite, 
  and 
  

   also 
  in 
  Franklin, 
  New 
  Jersey, 
  where, 
  according 
  to 
  Dr. 
  Fowler, 
  the 
  

   graphite 
  disseminated 
  in 
  the 
  magnetic 
  iron 
  ore 
  is 
  an 
  obstacle 
  to 
  

   the 
  working 
  of 
  it 
  in 
  the 
  forge 
  (Rogers, 
  Final 
  Rep. 
  Geo!. 
  New 
  

   Jersey, 
  page 
  64). 
  Beck 
  has 
  also 
  described, 
  as 
  occuring 
  near 
  the 
  

   Natural 
  Bridge, 
  in 
  Lewis 
  county, 
  New 
  York, 
  a 
  mixture 
  of 
  chlorite, 
  

   graphite 
  and 
  red 
  iron 
  ore, 
  the 
  latter 
  amounting 
  to 
  about 
  one-half 
  

   of 
  the 
  mass 
  (Mineralogy 
  of 
  New 
  York, 
  page 
  26). 
  The 
  presence 
  

   of 
  graphite 
  in 
  the 
  hematite 
  which 
  is 
  associated 
  with 
  magnetite 
  in 
  

   Hull, 
  has 
  already 
  been 
  noticed 
  above. 
  It 
  is, 
  however, 
  chiefly 
  in 
  

   the 
  limestones 
  that 
  we 
  find 
  graphite 
  disseminated, 
  sometimes 
  so 
  

   finely 
  divided 
  as 
  to 
  give 
  a 
  bluish-grey 
  tint 
  to 
  certain 
  bands 
  mark- 
  

   ing 
  the 
  stratification, 
  and 
  at 
  other 
  times 
  appearing 
  in 
  thin 
  detached 
  

   films 
  or 
  flakes, 
  also 
  marking 
  the 
  stratification. 
  Portions 
  of 
  the 
  rock 
  

   in 
  this 
  w 
  T 
  ay 
  sometimes 
  become 
  highly 
  charged 
  with 
  graphite, 
  and 
  

   may 
  form 
  workable 
  beds, 
  but 
  it 
  is 
  doubtful 
  whether 
  accumula- 
  

   tions 
  of 
  pure 
  crystalline 
  graphite 
  ever 
  occur 
  in 
  the 
  stratification. 
  

  

  Specimens 
  of 
  an 
  impure 
  amorphous 
  graphite 
  have 
  lately 
  been 
  

   brought 
  from 
  Clarendon, 
  Ontario, 
  where 
  it 
  is 
  said 
  to 
  form 
  a 
  bed 
  

   of 
  fifteen 
  inches 
  in 
  thickness, 
  in 
  a 
  fine 
  grained 
  mica-slate. 
  The 
  

   mineral 
  is 
  sub-conchoidal 
  in 
  fracture, 
  earthy, 
  bluish-black 
  in 
  color, 
  

   dull, 
  but 
  assuming 
  the 
  lustre 
  of 
  graphite 
  under 
  the 
  burnisher. 
  It 
  

   loses 
  by 
  ignition 
  only 
  0.4 
  of 
  volatile 
  matter 
  ; 
  by 
  a 
  prolonged 
  cal- 
  

   cination 
  in 
  the 
  open 
  air, 
  however, 
  the 
  graphite 
  is 
  burned 
  away, 
  

   leaving 
  66.16 
  per 
  cent 
  of 
  brownish-yellow 
  residue, 
  which 
  yields 
  

   to 
  acids 
  a 
  little 
  lime, 
  magnesia 
  and 
  oxyd 
  of 
  iron, 
  and 
  then 
  consists 
  

   chiefly 
  of 
  a 
  silicate 
  in 
  large 
  part 
  aluminous. 
  This 
  anhydrous 
  

   argillaceous 
  rock 
  thus 
  contains 
  very 
  nearly 
  one-third 
  its 
  weight 
  

   of 
  amorphous 
  or 
  uncrystalline 
  graphite. 
  

  

  Crystalline 
  graphite 
  is 
  one 
  of 
  the 
  most 
  frequent 
  minerals 
  of 
  the 
  

   Laurentian 
  veins, 
  in 
  which 
  it 
  occurs 
  under 
  a 
  variety 
  of 
  aspects, 
  

   sometimes 
  as 
  large 
  plates, 
  or 
  hexagonal 
  tables, 
  disseminated 
  in 
  

   coarse-grained 
  calcite, 
  vitreous 
  quartz, 
  orthoclase 
  or 
  pyroxene, 
  in 
  

  

  