﻿ADIRONDACK 
  MAGNETIC 
  IRON 
  ORES 
  I3I 
  

  

  north 
  and 
  east 
  of 
  Harris 
  ville, 
  recognizable 
  gabbro 
  outcrops 
  

   have 
  been 
  found. 
  These 
  rocks, 
  it 
  may 
  be 
  noted, 
  are 
  compara- 
  

   tively 
  rare, 
  in 
  contrast 
  with 
  their 
  wide 
  distribution 
  elsewhere 
  in 
  the 
  

   Adirondacks. 
  

  

  A 
  prominent 
  member 
  of 
  the 
  gneiss 
  series 
  is 
  a 
  coarse 
  reddish 
  

   hornblende 
  rock 
  which 
  has 
  the 
  composition 
  of 
  granite. 
  It 
  is 
  abun- 
  

   dant 
  in 
  the 
  region 
  east 
  of 
  Harrisville, 
  particularly 
  between 
  Benson 
  

   Mines 
  and 
  Cranberry 
  lake 
  and 
  the 
  section 
  northward. 
  Its 
  affinities 
  

   are 
  with 
  the 
  igneous 
  rocks, 
  as 
  indicated 
  by 
  field 
  evidence 
  in 
  places, 
  

   though 
  further 
  investigation 
  is 
  needed 
  to 
  prove 
  that 
  the 
  gneiss 
  is 
  

   of 
  uniform 
  character 
  and 
  derivation. 
  

  

  Certain 
  representatives 
  of 
  the 
  gneisses 
  are 
  undoubted 
  meta- 
  

   morphosed 
  sediments, 
  yet 
  contain 
  no 
  included 
  bands 
  of 
  limestone. 
  

   Their 
  sedimentary 
  origin 
  is 
  traced 
  by 
  their 
  mineralogical 
  and 
  

   textural 
  peculiarities. 
  They 
  have 
  a 
  variable 
  composition, 
  light 
  

   colored 
  quartzose 
  varieties 
  alternating 
  across 
  the 
  strike 
  with 
  dark 
  

   varieties 
  in 
  which 
  there 
  is 
  a 
  considerable 
  proportion 
  of 
  hornblende, 
  

   mica 
  or 
  pyroxene. 
  Garnet 
  is 
  a 
  frequent 
  constituent 
  and 
  pyrite 
  is 
  

   seldom 
  wanting. 
  Sillimanite 
  also 
  appears, 
  but 
  rarely 
  in 
  crystals 
  

   sufficiently 
  large 
  to 
  be 
  distinguished 
  without 
  the 
  aid 
  of 
  the 
  micro- 
  

   scope. 
  The 
  constituents 
  have 
  a 
  granular 
  habit, 
  without 
  the 
  definite 
  

   arrangement 
  or 
  texture 
  which 
  obtains 
  in 
  igneous 
  rocks. 
  These 
  

   gneisses 
  are 
  to 
  be 
  classed 
  as 
  members 
  of 
  the 
  Grenville 
  series. 
  They 
  

   are 
  very 
  much 
  like 
  the 
  hornblende 
  and 
  mica 
  gneisses 
  that 
  occur 
  

   over 
  large 
  areas 
  in 
  the 
  eastern 
  Adirondacks 
  and 
  which 
  have 
  been 
  

   assigned 
  to 
  the 
  base 
  of 
  the 
  Grenville. 
  

  

  Description 
  of 
  mines 
  

  

  Benson 
  mines. 
  The 
  deposits 
  are 
  in 
  the 
  town 
  of 
  Clifton, 
  on 
  the 
  

   north 
  side 
  of 
  Little 
  river. 
  Benson 
  Mines 
  is 
  a 
  hamlet 
  and 
  a 
  railroad 
  

   station, 
  43 
  miles 
  east 
  of 
  Carthage. 
  The 
  valley 
  lies 
  at 
  an 
  elevation 
  

   of 
  about 
  1600 
  feet, 
  while 
  the 
  limiting 
  ridges 
  are 
  somewhat 
  more 
  

   than 
  2000 
  feet. 
  

  

  In 
  his 
  report 
  on 
  the 
  Second 
  District, 
  1 
  Emmons 
  mentions 
  the 
  

   occurrence 
  of 
  magnetite 
  bodies 
  on 
  the 
  Oswegatchie 
  river 
  near 
  the 
  

   crossing 
  of 
  the 
  former 
  highway 
  known 
  as 
  the 
  Albany 
  road. 
  From 
  

   the 
  accompanying 
  description 
  it 
  is 
  evident 
  that 
  the 
  present 
  Benson 
  

   mines 
  are 
  referred 
  to; 
  and 
  the 
  stream 
  now 
  known 
  as 
  Little 
  river 
  

   was 
  probably 
  designated 
  on 
  the 
  old 
  maps 
  as 
  the 
  Oswegatchie 
  of 
  

   which 
  it 
  is 
  a 
  tributary. 
  Emmons 
  states 
  that 
  a 
  considerable 
  quan- 
  

  

  1 
  Survey 
  of 
  the 
  Second 
  Geological 
  District. 
  1842. 
  p. 
  347. 
  

  

  