﻿ADIRONDACK 
  MAGNETIC 
  IRON 
  ORES 
  143 
  

  

  The 
  immediate 
  area 
  about 
  the 
  mine 
  is 
  occupied 
  by 
  the 
  Adiron- 
  

   dack 
  Precambrics. 
  These 
  rocks 
  extend 
  southward 
  as 
  a 
  belt 
  of 
  

   gradually 
  diminishing 
  width 
  to 
  within 
  4 
  miles 
  of 
  Little 
  Falls, 
  pass- 
  

   ing 
  at 
  the 
  borders 
  beneath 
  the 
  Lower 
  Siluric 
  strata 
  (Beekmantown, 
  

   Trenton 
  and 
  Lorraine) 
  which 
  spread 
  over 
  the 
  region 
  to 
  the 
  south. 
  

   There 
  is 
  a 
  large 
  outlier 
  of 
  Precambric 
  syenite 
  at 
  Little 
  Falls 
  and 
  

   smaller 
  ones 
  of 
  the 
  same 
  rock 
  at 
  Middle 
  ville, 
  northwest 
  of 
  Little 
  

   Falls, 
  and 
  at 
  a 
  point 
  about 
  half 
  way 
  between 
  the 
  latter 
  locality 
  

   and 
  the 
  southern 
  end 
  of 
  the 
  main 
  area. 
  The 
  contact 
  between 
  the 
  

   Precambric 
  and 
  Paleozoic 
  strata 
  on 
  the 
  east 
  side 
  of 
  the 
  belt 
  is 
  

   marked 
  by 
  a 
  heavy 
  fault 
  which 
  begins 
  south 
  of 
  the 
  Mohawk 
  river 
  

   and 
  runs 
  northeast 
  passing 
  about 
  2 
  miles 
  east 
  of 
  the 
  mine. 
  

  

  The 
  principal 
  representative 
  of 
  the 
  Precambric 
  rocks 
  is 
  syenite, 
  

   a 
  greenish 
  augite-bearing 
  variety 
  that 
  is 
  identical 
  mineralogically 
  

   with 
  the 
  great 
  syenite 
  masses 
  in 
  the 
  central 
  Adirondacks. 
  It 
  has 
  

   a 
  gneissoid 
  appearance 
  in 
  most 
  cases 
  and 
  shows 
  strong 
  crushing 
  

   effects 
  in 
  the 
  granulation 
  of 
  the 
  feldspar. 
  Occasionally 
  uncrushed 
  

   remnants 
  of 
  feldspar 
  may 
  be 
  observed 
  surrounded 
  by 
  granular 
  

   material, 
  like 
  an 
  augen 
  gneiss. 
  The 
  syenite 
  is 
  exposed 
  over 
  most 
  

   of 
  the 
  area 
  north 
  of 
  Salisbury 
  Center. 
  

  

  The 
  Grenville 
  series 
  of 
  gneisses 
  and 
  schists 
  form 
  the 
  southern 
  

   extension 
  of 
  the 
  Precambric 
  belt 
  south 
  of 
  Salisbury 
  Center 
  and 
  is 
  

   exposed 
  north 
  of 
  the 
  mine 
  in 
  two 
  areas 
  which 
  are 
  bordered 
  bv 
  the 
  

   syenite. 
  It 
  consists 
  of 
  light 
  colored 
  quartzose 
  gneisses 
  interbanded 
  

   with 
  darker 
  hornblendic 
  or 
  micaceous 
  varieties. 
  Crystalline 
  lime- 
  

   stone, 
  usually 
  a 
  prominent 
  member 
  of 
  the 
  series, 
  apparently 
  has 
  a 
  

   very 
  limited 
  development 
  within 
  the 
  area 
  ; 
  the 
  only 
  outcrop 
  that 
  has 
  

   been 
  recorded 
  is 
  one 
  observed 
  by 
  the 
  writer 
  at 
  a 
  point 
  a 
  little 
  

   north 
  of 
  Salisbury 
  Center. 
  The 
  gneisses 
  are 
  believed 
  by 
  Cushing 
  

   to 
  represent 
  original 
  sandstones 
  and 
  shales. 
  

  

  A 
  reddish 
  gneiss 
  comprised 
  mainly 
  of 
  quartz 
  and 
  alkali 
  feldspar 
  

   occurs 
  at 
  a 
  few 
  places 
  in 
  association 
  with 
  the 
  syenite 
  and 
  rocks 
  of 
  

   the 
  Grenville 
  series. 
  Its 
  field 
  relations 
  as 
  well 
  as 
  its 
  composition 
  

   suggest 
  an 
  original 
  granite 
  that 
  is 
  probably 
  intrusive 
  in 
  the 
  sedi- 
  

   mentary 
  gneisses. 
  Cushing 
  mentions 
  also 
  the 
  occurrence 
  of 
  black 
  

   gneisses, 
  containing 
  hornblende 
  and 
  biotite 
  and 
  occasionally 
  

   pyroxene, 
  and 
  gray 
  gneisses 
  of 
  granitic 
  composition 
  which 
  are 
  

   regarded 
  as 
  igneous 
  derivatives. 
  

  

  Ore 
  bodies. 
  The 
  deposit 
  which 
  has 
  been 
  principally 
  worked 
  

   extends 
  nearly 
  east 
  and 
  west 
  along 
  the 
  highway 
  2 
  J 
  miles 
  north 
  of 
  

   Salisbury 
  Center. 
  It 
  consists 
  of 
  an 
  elongated 
  zone 
  made 
  up 
  of 
  

   magnetite 
  in 
  one 
  or 
  more 
  bands 
  intercalated 
  between 
  layers 
  of 
  

  

  