﻿ADIRONDACK 
  MAGNETIC 
  IRON 
  ORES 
  

  

  95 
  

  

  the 
  lines 
  of 
  outcrop 
  are 
  shifted 
  laterally. 
  In 
  the 
  heading 
  of 
  the 
  

   south 
  shaft 
  of 
  the 
  Nelson 
  Bush 
  mine 
  a 
  fault 
  of 
  this 
  kind 
  was 
  

   observed. 
  Its 
  throw 
  could 
  not 
  be 
  determined 
  but 
  it 
  is 
  probably 
  

   small. 
  Other 
  examples 
  which 
  have 
  been 
  noted 
  by 
  Emmons 
  occur 
  

   in 
  the 
  old 
  workings 
  on 
  the 
  southern 
  section, 
  where 
  the 
  outcropping 
  

   ore 
  is 
  offset 
  by 
  slight 
  displacements 
  that 
  have 
  taken 
  place 
  obliquely 
  

   to 
  the 
  dip. 
  The 
  maximum 
  offset 
  found 
  on 
  the 
  surface 
  is 
  about 
  15 
  

   feet. 
  In 
  this 
  case 
  a 
  thin 
  dike 
  has 
  been 
  intruded 
  along 
  the 
  fault 
  

   plane 
  [fig. 
  15]. 
  

  

  The 
  wall 
  rock 
  is 
  mainly 
  the 
  augite 
  variety 
  of 
  acid 
  gneiss 
  already 
  

   described. 
  Along 
  the 
  contact 
  with 
  the 
  ore 
  it 
  has 
  been 
  considerably 
  

   altered, 
  with 
  the 
  development 
  of 
  chlorite 
  and 
  biotite 
  as 
  resultant 
  

   products 
  from 
  the 
  augite, 
  while 
  it 
  also 
  contains 
  much 
  clear 
  quartz 
  

   of 
  secondary 
  infiltration. 
  A 
  black 
  hornblende 
  gneiss 
  is 
  encoun- 
  

  

  Fig. 
  is 
  Faulting 
  of 
  the 
  ore 
  bodies 
  as 
  seen 
  on 
  the 
  surface 
  near 
  

   the 
  Indian 
  pit. 
  A 
  diabase 
  dike 
  has 
  been 
  intruded 
  along 
  the 
  

   fault 
  plane 
  at 
  the 
  right. 
  

  

  tered 
  on 
  the 
  walls 
  of 
  the 
  Nelson 
  Bush 
  mine, 
  and 
  may 
  represent 
  an 
  

   included 
  band 
  of 
  the 
  sedimentary 
  gneisses 
  to 
  which 
  it 
  corresponds 
  

   in 
  composition. 
  

  

  Nelson 
  Bush 
  mine. 
  This 
  mine 
  is 
  the 
  most 
  northerly 
  of 
  the 
  

   Arnold 
  hill 
  workings. 
  It 
  consists 
  of 
  two 
  shafts 
  about 
  600 
  feet 
  

   apart 
  driven 
  on 
  the 
  course 
  of 
  two 
  lenses 
  which 
  have 
  nearly 
  the 
  

   same 
  horizontal 
  axis. 
  Underground 
  the 
  shafts 
  run 
  off 
  as 
  inclines, 
  

   the 
  northern 
  starting 
  at 
  an 
  angle 
  of 
  6o° 
  and 
  flattening 
  gradually 
  

   to 
  30 
  and 
  the 
  southern 
  at 
  an 
  angle 
  varying 
  from 
  42 
  to 
  35 
  . 
  They 
  

   are 
  intended 
  to 
  follow 
  as 
  nearly 
  as 
  possible 
  the 
  pitch 
  of 
  the 
  lenses 
  

   which 
  is 
  about 
  40 
  north. 
  The 
  north 
  shaft 
  is 
  down 
  some 
  900 
  feet 
  

   on 
  the 
  incline. 
  The 
  lens 
  of 
  ore 
  as 
  seen 
  in 
  the 
  workings 
  is 
  25 
  feet 
  

   thick 
  in 
  its 
  maximum 
  development 
  and 
  averages 
  perhaps 
  18 
  feet. 
  

   In 
  the 
  south 
  shaft 
  the 
  lens 
  ranges 
  from 
  10 
  to 
  15 
  feet 
  across 
  the 
  

   walls. 
  The 
  two 
  shafts 
  are 
  not 
  connected 
  underground. 
  

  

  The 
  ore 
  is 
  coarsely 
  granular 
  as 
  a 
  rule 
  and 
  contains 
  too 
  much 
  

  

  