﻿ADIRONDACK 
  MAGNETIC 
  IRON 
  ORES 
  1 
  57 
  

  

  Geology. 
  The 
  district 
  lies 
  within 
  the 
  main 
  anorthosite 
  area, 
  

   but 
  not 
  far 
  from 
  its 
  western 
  bounds. 
  As 
  delimited 
  in 
  the 
  prelimi- 
  

   nary 
  survey 
  of 
  J. 
  F. 
  Kemp, 
  1 
  the 
  gneiss 
  series 
  occupies 
  approximately 
  

   the 
  western 
  half 
  of 
  Newcomb 
  township, 
  the 
  line 
  of 
  contact 
  with 
  

   the 
  anorthosite 
  which 
  extends 
  over 
  the 
  eastern 
  half 
  trending 
  some- 
  

   what 
  west 
  of 
  north. 
  It 
  is 
  not 
  easy 
  to 
  fix 
  accurately 
  the 
  limits 
  of 
  

   the 
  formations 
  owing 
  to 
  the 
  drift 
  which 
  chokes 
  the 
  valleys 
  and 
  

   reaches 
  well 
  up 
  the 
  slopes 
  of 
  the 
  ridges. 
  Anorthosite 
  has 
  been 
  

   found 
  by 
  the 
  writer 
  to 
  outcrop 
  on 
  Santanoni 
  mountain, 
  about 
  5 
  

   miles 
  directly 
  west 
  of 
  Lakes 
  Sanford 
  and 
  Henderson, 
  so 
  that 
  it 
  prob- 
  

   ably 
  continues 
  in 
  unbroken 
  mass 
  that 
  far. 
  The 
  gneiss 
  series 
  first 
  

   appears 
  on 
  the 
  shores 
  of 
  Newcomb 
  lake 
  and 
  in 
  the 
  east-west 
  valley 
  

   occupied 
  by 
  Rich 
  and 
  Harris 
  lakes, 
  whence 
  it 
  stretches 
  westward 
  

   as 
  far 
  as 
  the 
  confines 
  of 
  the 
  Adirondacks. 
  

  

  The 
  gneiss 
  series 
  bordering 
  the 
  anorthosite 
  has 
  been 
  subjected 
  

   only 
  to 
  a 
  cursory 
  examination. 
  Apparently 
  it 
  consists 
  of 
  a 
  com- 
  

   plex 
  in 
  which 
  both 
  sedimentary 
  and 
  igneous 
  types 
  are 
  represented. 
  

   The 
  former 
  have 
  particularly 
  strong 
  development 
  around 
  Newcomb, 
  

   where 
  there 
  is 
  one 
  of 
  the 
  largest 
  Grenville 
  exposures 
  in 
  the 
  interior 
  

   of 
  the 
  Adirondacks. 
  They 
  comprise 
  the 
  usual 
  rusty 
  micaceous 
  

   and 
  hornblendic 
  gneisses 
  and 
  schists, 
  with 
  interfolded 
  belts 
  of 
  

   crystalline 
  limestone 
  carrying 
  graphite 
  and 
  other 
  characteristic 
  

   minerals. 
  A 
  limestone 
  ledge 
  on 
  the 
  east 
  side 
  of 
  Newcomb 
  lake 
  

   was 
  a 
  source 
  of 
  flux 
  for 
  the 
  early 
  furnace 
  operations. 
  Professor 
  

   Cushing 
  in 
  his 
  recent 
  mapping 
  of 
  the 
  geology 
  of 
  the 
  Long 
  Lake 
  

   quadrangle 
  has 
  noted 
  the 
  presence 
  of 
  extensive 
  masses 
  of 
  syenite 
  

   and 
  granitic 
  gneisses, 
  and 
  it 
  is 
  not 
  unlikely 
  that 
  upon 
  further 
  investi- 
  

   gation 
  they 
  will 
  be 
  found 
  to 
  constitute 
  an 
  important 
  part 
  of 
  the 
  area 
  

   farther 
  east 
  along 
  with 
  the 
  Grenville 
  formation. 
  The 
  region 
  

   about 
  the 
  mines 
  is 
  included 
  in 
  the 
  Santanoni 
  quadrangle 
  which 
  

   adjoins 
  the 
  Long 
  Lake 
  sheet 
  on 
  the 
  east. 
  

  

  The 
  principal 
  interest 
  in 
  connection 
  with 
  the 
  iron 
  ores 
  is' 
  

   attached, 
  of 
  course, 
  to 
  the 
  anorthosite. 
  Where 
  exposed 
  near 
  the 
  

   mines 
  this 
  is 
  generally 
  a 
  very 
  typical 
  variety 
  of 
  the 
  rock 
  as 
  devel- 
  

   oped 
  in 
  the 
  Adirondack 
  region. 
  It 
  consists 
  essentially 
  of 
  labra- 
  

   dorite 
  in 
  grayish 
  or 
  bluish 
  black 
  crystals, 
  that 
  occasionally 
  exhibit 
  

   a 
  play 
  of 
  colors 
  on 
  cleavage 
  surfaces. 
  The 
  crystals 
  are 
  generally 
  

   large, 
  up 
  to 
  3 
  or 
  4 
  inches 
  in 
  length, 
  and 
  are 
  closely 
  interwoven 
  

   with 
  a 
  coarsely 
  granitic 
  texture. 
  While 
  as 
  a 
  rale 
  the 
  feldspar 
  

   constitutes 
  practically 
  the 
  only 
  mineral 
  observable 
  in 
  hand 
  speci- 
  

  

  1 
  Preliminary 
  Report 
  on 
  the 
  Geology 
  of 
  Essex 
  County. 
  N. 
  Y. 
  State 
  Mus. 
  

   4Qth 
  An. 
  Rep't. 
  1898. 
  2:604. 
  

  

  