﻿FOURTH 
  REPORT 
  OF 
  THE 
  DIRECTOR 
  I907 
  7 
  1 
  

  

  lationships, 
  and 
  with 
  the 
  schists 
  and 
  limestones 
  of 
  the 
  sedimentary 
  

   (Grenville) 
  type. 
  Their 
  origin 
  is 
  obscure, 
  a 
  problem 
  that 
  has 
  been 
  

   fruitful 
  in 
  discussion 
  and 
  theorizing 
  among 
  geologists. 
  It 
  is 
  doubt- 
  

   ful 
  if 
  any 
  one 
  of 
  the 
  explanations 
  that 
  have 
  been 
  advanced 
  is 
  satis- 
  

   factory 
  as 
  a 
  general 
  basis 
  for 
  the 
  whole 
  group 
  ; 
  rather 
  it 
  would 
  seem 
  

   that 
  the 
  varying 
  conditions 
  surrounding 
  the 
  character 
  and 
  associa- 
  

   tions 
  of 
  the 
  deposits 
  indicate 
  that 
  they 
  have 
  been 
  formed 
  by 
  a 
  com- 
  

   plexity 
  of 
  processes 
  which 
  may 
  have 
  differed 
  materially 
  in 
  individual 
  

   cases. 
  

  

  The 
  titaniferous 
  magnetites 
  are 
  distinguished 
  from 
  those 
  of 
  the 
  

   preceding 
  group 
  by 
  their 
  higher 
  percentage 
  of 
  titanium, 
  which 
  

   ranges 
  from 
  about 
  3 
  or 
  4 
  per 
  cent, 
  as 
  a 
  minimum 
  up 
  to 
  a 
  maximum 
  

   of 
  10 
  or 
  15 
  per 
  cent, 
  and 
  by 
  the 
  fact 
  that 
  they 
  are 
  always 
  inclosed 
  

   by 
  basic 
  igneous 
  rocks 
  of 
  the 
  gabbro 
  family. 
  They 
  have 
  been 
  de- 
  

   scribed 
  by 
  Prof. 
  J. 
  F. 
  Kemp 
  as 
  basic 
  segregations 
  formed 
  during 
  

   the 
  cooling 
  and 
  consolidation 
  of 
  the 
  wall 
  rocks, 
  an 
  explanation 
  that 
  

   is 
  generally 
  regarded 
  as 
  correct. 
  Some 
  of 
  the 
  largest 
  deposits 
  of 
  

   iron 
  ores 
  in 
  the 
  region 
  belong 
  to 
  this 
  class, 
  those 
  of 
  Lake 
  Sanford 
  

   being 
  specially 
  extensive. 
  After 
  a 
  long 
  period 
  of 
  inactivity, 
  due 
  

   to 
  the 
  difficulties 
  encountered 
  in 
  smelting 
  the 
  ores 
  in 
  the 
  blast 
  fur- 
  

   naces, 
  attention 
  is 
  now 
  being 
  directed 
  to 
  the 
  deposits 
  with 
  a 
  view 
  

   to 
  their 
  utilization. 
  It 
  has 
  been 
  found 
  that 
  the 
  ores 
  in 
  some 
  cases 
  

   at 
  least 
  are 
  not 
  simply 
  magnetite 
  carrying 
  titanium 
  uniformly 
  

   through 
  its 
  mass, 
  but 
  that 
  they 
  consist 
  of 
  a 
  mixture 
  of 
  magnetite 
  

   and 
  ilmenite, 
  the 
  former 
  having 
  almost 
  no 
  titanium, 
  a 
  condition 
  that 
  

   is 
  favorable 
  to 
  their 
  commercial 
  treatment. 
  

  

  The 
  hematite 
  ores 
  are 
  practically 
  limited 
  to 
  the 
  western 
  Adiron- 
  

   dack 
  region 
  of 
  St 
  Lawrence 
  and 
  Jefferson 
  counties. 
  In 
  this 
  area 
  

   the 
  Grenville 
  schists 
  and 
  limestones 
  attain 
  wide 
  development, 
  form- 
  

   ing 
  an 
  interbedded 
  series 
  which 
  has 
  been 
  upturned 
  and 
  sharply 
  

   folded. 
  Granite 
  intrusions 
  are 
  numerous, 
  but 
  there 
  is 
  a 
  noticeable 
  

   lack 
  of 
  the 
  basic 
  igneous 
  rocks 
  that 
  occur 
  abundantly 
  in 
  the 
  central 
  

   and 
  eastern 
  Adirondacks. 
  The 
  ore 
  bodies 
  consist 
  of 
  lenticular, 
  

   tabular, 
  or 
  irregular 
  masses 
  inclosed 
  within 
  belts 
  of 
  the 
  schist 
  and 
  

   limestone, 
  or 
  lying 
  along 
  the 
  contact 
  of 
  these 
  rocks 
  as 
  at 
  the 
  Cale- 
  

   donia 
  mine. 
  Stringers 
  and 
  larger 
  bands 
  of 
  ore 
  often 
  extend 
  out 
  

   from 
  the 
  main 
  bodies 
  for 
  considerable 
  distances 
  into 
  the 
  foot 
  and 
  

   hanging 
  walls. 
  The 
  deposits 
  have 
  originated, 
  without 
  much 
  doubt, 
  

   by 
  a 
  process 
  of 
  replacement. 
  They 
  grade 
  at 
  the 
  borders 
  into 
  the 
  

   wall 
  rock 
  and 
  frequently 
  inclusions 
  may 
  be 
  found 
  that 
  show 
  com- 
  

   plete 
  transition 
  from 
  the 
  rock 
  to 
  the 
  ore. 
  Where 
  the 
  walls 
  are 
  

  

  