﻿ADIRONDACK 
  MAGNETIC 
  IRON 
  ORES 
  33 
  

  

  to 
  some 
  process 
  of 
  sedimentation 
  as 
  outlined 
  above, 
  but 
  it 
  would 
  

   appear 
  to 
  the 
  writer 
  more 
  reasonable 
  to 
  regard 
  them 
  as 
  introduc- 
  

   tions 
  subsequent 
  to 
  the 
  formation 
  of 
  the 
  wall 
  rocks. 
  They 
  

   apparently 
  antedate 
  the 
  period 
  of 
  deformation 
  during 
  which 
  the 
  sur- 
  

   rounding 
  rocks 
  were 
  subjected 
  to 
  their 
  final 
  compression 
  and 
  folding. 
  

  

  As 
  a 
  rule 
  the 
  deposits 
  are 
  more 
  irregular 
  than 
  would 
  be 
  

   expected 
  in 
  stratified 
  bodies. 
  They 
  have 
  no 
  well 
  defined 
  bounds, 
  

   but 
  shade 
  off 
  into 
  the 
  country 
  rock. 
  It 
  is 
  seldom 
  that 
  the 
  charac- 
  

   ter 
  of 
  the 
  hanging 
  and 
  foot 
  shows 
  any 
  marked 
  change 
  that 
  can 
  

   be 
  taken 
  for 
  original 
  variations 
  in 
  the 
  sedimentation. 
  The 
  thick- 
  

   ness 
  of 
  some 
  of 
  the 
  deposits 
  is 
  excessive 
  when 
  compared 
  with 
  

   known 
  examples 
  of 
  bedded 
  iron 
  ores; 
  the 
  Benson 
  body, 
  for 
  

   example, 
  measures 
  over 
  200 
  feet 
  across 
  the 
  strike 
  and 
  the 
  country 
  

   rock 
  is 
  mineralized 
  over 
  much 
  greater 
  width. 
  

  

  Though 
  it 
  is 
  believed 
  that 
  the 
  ores 
  are 
  of 
  epigenetic 
  or 
  secondary 
  

   derivation, 
  there 
  is 
  little 
  basis 
  of 
  facts 
  to 
  support 
  a 
  more 
  precise 
  

   explanation 
  of 
  their 
  origin. 
  The 
  view 
  that 
  they 
  were 
  formed 
  

   before 
  the 
  surrounding 
  rocks 
  had 
  undergone 
  final 
  rearrangement 
  

   appears 
  reasonable, 
  because 
  they 
  have 
  laminated 
  textures 
  and 
  follow 
  

   closely 
  the 
  general 
  field 
  structures. 
  Their 
  introduction 
  may 
  thus 
  

   have 
  taken 
  place 
  before 
  the 
  rocks 
  were 
  metamorphosed, 
  in 
  which 
  

   case 
  it 
  might 
  have 
  been 
  accomplished 
  by 
  ordinary 
  ground-water 
  

   circulations, 
  with 
  limonite 
  or 
  carbonate 
  replacing 
  the 
  shales 
  and 
  

   limestones 
  as 
  the 
  first 
  step. 
  The 
  presence 
  of 
  organic 
  matter 
  in 
  the 
  

   beds, 
  indicated 
  by 
  their 
  content 
  of 
  graphite, 
  would 
  exercise 
  a 
  

   reducing 
  action 
  favorable 
  to 
  the 
  formation 
  of 
  magnetite 
  rather 
  than 
  

   hematite 
  under 
  the 
  ensuing 
  met 
  amorphic 
  conditions. 
  

  

  Mining 
  and 
  milling 
  in 
  the 
  Adirondacks 
  

  

  Both 
  underground 
  and 
  open-cut 
  methods 
  are 
  used 
  in 
  the 
  Adi- 
  

   rondack 
  mines, 
  the 
  latter, 
  however, 
  being 
  restricted 
  to 
  a 
  few 
  large 
  

   ore 
  bodies 
  or 
  those 
  so 
  situated 
  as 
  to 
  present 
  a 
  considerable 
  surface 
  

   development. 
  In 
  general 
  the 
  high 
  inclination 
  of 
  the 
  bodies 
  and 
  

   their 
  narrowness 
  across 
  the 
  strike 
  render 
  a 
  system 
  of 
  underground 
  

   working 
  the 
  most 
  suitable 
  from 
  the 
  start. 
  Inclined 
  shafts 
  or 
  

   slopes 
  following 
  the 
  dip 
  of 
  the 
  ore 
  have 
  been 
  generally 
  adopted 
  in 
  

   preference 
  to 
  vertical 
  shafts 
  which 
  in 
  some 
  instances 
  at 
  least 
  would 
  

   seem 
  to 
  offer 
  important 
  advantages 
  as 
  regards 
  economy 
  of 
  opera- 
  

   tion. 
  The 
  deepest 
  shafts 
  are 
  at 
  Lyon 
  Mountain, 
  about 
  1500 
  feet 
  

   measured 
  on 
  the 
  incline. 
  Horizontal 
  drifts 
  are 
  extended 
  on 
  either 
  

   side 
  of 
  the 
  shaft 
  at 
  more 
  or 
  less 
  regular 
  intervals 
  and 
  the 
  ore 
  stoped 
  

   out 
  between 
  them, 
  leaving 
  occasional 
  pillars 
  of 
  ore 
  for 
  roof 
  sup- 
  

  

  