﻿58 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  The 
  most 
  interesting 
  and 
  important 
  magnetite 
  deposits 
  occur 
  in 
  

   the 
  village 
  of 
  Port 
  Leyden 
  and 
  on 
  the 
  west 
  side 
  of 
  the 
  river 
  below 
  

   the 
  bridge. 
  Many 
  years 
  ago 
  several 
  attempts 
  were 
  made 
  to 
  mine 
  

   the 
  ore 
  here. 
  An 
  ore 
  pit, 
  now 
  filled 
  with 
  water, 
  was 
  run 
  down 
  

   some 
  50 
  or 
  60 
  feet 
  and 
  a 
  furnace 
  was 
  erected, 
  but 
  the 
  mine 
  was 
  

   never 
  a 
  paying 
  proposition. 
  Ore 
  was 
  later 
  brought 
  to 
  the 
  furnace 
  

   from 
  other 
  places. 
  The 
  ore 
  is 
  magnetite 
  associated 
  with 
  much 
  iron 
  

   pyrites 
  and 
  often 
  with 
  quartz. 
  A 
  thin 
  section 
  of 
  the 
  ore 
  from 
  the 
  

   pit 
  shows 
  ^o'jc 
  of 
  quartz; 
  45^ 
  of 
  magnetite 
  and 
  pyrite 
  and 
  5^ 
  of 
  

   badly 
  decomposed 
  ferro-magnesian 
  minerals. 
  The 
  wall 
  rock 
  from 
  

   the 
  pit 
  shows 
  35^ 
  of 
  feldspar, 
  chiefly 
  microperthite 
  and 
  some 
  oli- 
  

   gogclase 
  ; 
  45^ 
  of 
  quartz 
  and 
  20^ 
  of 
  biotite, 
  pyrite, 
  sillimanite, 
  zircon 
  

   and 
  garnet. 
  Thirty 
  feet 
  from 
  the 
  ore 
  pit, 
  the 
  feldspar 
  content 
  is 
  

   somewhat 
  higher 
  and 
  the 
  dark 
  minerals 
  not 
  so 
  prominent. 
  Still 
  

   farther 
  away 
  the 
  rock 
  is 
  much 
  like 
  a 
  quartzose 
  syenite. 
  A 
  few 
  rods 
  

   from 
  this 
  pit 
  and 
  at 
  the 
  water's 
  edge, 
  an 
  irregular 
  shaped 
  ore 
  body 
  

   several 
  feet 
  across 
  may 
  be 
  seen. 
  It 
  is 
  nearly 
  pure 
  magnetite 
  and 
  

   entirely 
  surrounded 
  by 
  syenite. 
  The 
  ore 
  is 
  in 
  no 
  sense 
  sharply 
  

   separated 
  from 
  the 
  country 
  rock. 
  A 
  rapid 
  but 
  perfect 
  gradation 
  

   of 
  the 
  ore 
  into 
  the 
  syenite 
  may 
  be 
  seen 
  and 
  the 
  evidence 
  seems 
  con- 
  

   clusive 
  that 
  this 
  small 
  ore 
  body, 
  at 
  least, 
  is 
  a 
  segregation 
  mass 
  in 
  

   the 
  syenite. 
  The 
  ore 
  in 
  the 
  pit 
  is 
  thought 
  to 
  have 
  a 
  similar 
  origin, 
  

   although 
  the 
  evidence 
  is 
  not 
  there 
  quite 
  so 
  conclusive. 
  This 
  ore 
  is 
  

   closely 
  associated 
  with 
  syenite 
  and 
  garnetiferous 
  gneisses 
  in 
  a 
  

   syenite-Grenville 
  area 
  and 
  it 
  is 
  interesting 
  to 
  note 
  that 
  the 
  Salis- 
  

   bury 
  Iron 
  Mine 
  described 
  by 
  Gushing 
  on 
  the 
  Little 
  Falls 
  quad- 
  

   rangle, 
  and 
  the 
  occurrences 
  noted 
  by 
  the 
  writer 
  on 
  the 
  Remsen 
  

   quadrangle, 
  all 
  show 
  similar 
  relationships 
  to 
  the 
  country 
  rock. 
  It 
  

   would 
  seem 
  that 
  when 
  the 
  molten 
  syenite 
  was 
  passing 
  through 
  the 
  

   Grenville 
  the 
  conditions 
  were 
  somehow 
  made 
  favorable 
  for 
  the 
  

   segregation 
  of 
  the 
  magnetite. 
  

  

  Lead 
  ore 
  

  

  Before 
  the 
  middle 
  of 
  the 
  last 
  century 
  lead 
  ore 
  was 
  discovered 
  in 
  

   the 
  Trenton 
  limestone 
  about 
  a 
  mile 
  a 
  little 
  west 
  of 
  north 
  of 
  

   Martinsburg. 
  The 
  early 
  attempts 
  to 
  mine 
  the 
  ore 
  and 
  extract 
  the 
  

   metal 
  failed 
  because 
  of 
  the 
  small 
  quantity 
  of 
  ore 
  available. 
  The 
  

   ore 
  is 
  galena 
  (sulphid 
  of 
  lead) 
  which 
  occurs 
  in 
  true 
  vein 
  deposits 
  

   and 
  associated 
  with 
  calcite 
  as 
  a 
  gangue 
  material. 
  The 
  calcite 
  is 
  

   frequently 
  crystallized 
  in 
  six-sided 
  prisms 
  capped 
  by 
  three-sided 
  

   pyramids. 
  The 
  vein-stuff 
  fills 
  joints 
  in 
  the 
  limestone 
  and 
  the 
  galena 
  

   has 
  doubtless 
  been 
  dissolved 
  out 
  of 
  the 
  surrounding 
  rock 
  and 
  de- 
  

   posited 
  in 
  the 
  veins. 
  

  

  