﻿26 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  the 
  talc 
  and 
  in 
  the 
  same 
  geological 
  surroundings, 
  is 
  a 
  noteworthy 
  

   feature 
  which 
  has 
  only 
  recently 
  attracted 
  attention. 
  The 
  ores 
  form 
  

   pockets 
  and 
  bands 
  in 
  limestones 
  and 
  schist 
  with 
  the 
  characteristics 
  

   of 
  replacement 
  deposits. 
  In 
  any 
  case, 
  they 
  have 
  undoubtedly 
  been 
  

   introduced 
  in 
  solution 
  and 
  precipitated 
  in 
  their 
  present 
  place 
  after 
  

   the 
  upraising 
  of 
  the 
  sediments 
  represented 
  by 
  the 
  wall 
  rocks. 
  It 
  

   would 
  appear 
  probable 
  from 
  these 
  and 
  from 
  other 
  considerations 
  

   which 
  need 
  not 
  be 
  entered 
  upon 
  here 
  that 
  there 
  is 
  a 
  close 
  genetic 
  

   relation 
  between 
  the 
  talc 
  and 
  the 
  metallic 
  minerals. 
  This 
  point 
  is 
  

   of 
  some 
  significance 
  in 
  regard 
  to 
  the 
  probable 
  extent 
  of 
  the 
  talc 
  

   deposits 
  and 
  renders 
  a 
  more 
  detailed 
  investigation 
  of 
  the 
  field 
  highly 
  

   desirable. 
  

  

  Zinc. 
  A 
  brief 
  visit 
  to 
  the 
  zinc 
  ore 
  localities 
  of 
  St 
  Lawrence 
  

   county 
  was 
  made 
  during 
  the 
  summer 
  for 
  the 
  purpose 
  of 
  studying 
  

   the 
  occurrences 
  and 
  securing 
  material 
  for 
  the 
  collections. 
  There 
  

   has 
  been 
  much 
  activity 
  in 
  prospecting 
  within 
  the 
  district, 
  but 
  the 
  

   recent 
  developments 
  have 
  been 
  restricted, 
  as 
  in 
  the 
  previous 
  year, 
  

   to 
  the 
  locality 
  near 
  Edwards. 
  As 
  the 
  result 
  of 
  recent 
  discoveries, 
  

   it 
  is 
  known 
  that 
  zinc 
  blende 
  has 
  a 
  rather 
  wide 
  distribution 
  in 
  the 
  

   section 
  from 
  Edwards 
  to 
  Sylvia 
  lake, 
  which 
  is 
  practically 
  coextensive 
  

   with 
  the 
  talc 
  district. 
  The 
  economic 
  importance 
  of 
  the 
  deposits 
  is 
  

   scarcely 
  to 
  be 
  estimated 
  as 
  yet, 
  but 
  the 
  work 
  on 
  the 
  single 
  property 
  

   that 
  is 
  under 
  exploration, 
  lends 
  encouragement 
  to 
  the 
  hope 
  that 
  a 
  

   substantial 
  industry 
  may 
  be 
  developed. 
  Some 
  difficulty 
  has 
  been 
  

   encountered 
  in 
  the 
  mill 
  treatment 
  of 
  the 
  ore 
  which 
  contains 
  more 
  

   or 
  less 
  pyrite 
  in 
  intimate 
  association 
  with 
  the 
  blende, 
  the 
  two 
  min- 
  

   erals 
  occurring 
  usually 
  in 
  finely 
  divided 
  intergrown 
  particles. 
  

  

  Field 
  observations 
  show 
  that 
  the 
  blende 
  is 
  found 
  in 
  crystalline 
  

   limestones 
  of 
  the 
  same 
  belt 
  that 
  includes 
  the 
  talc 
  and 
  tremolite 
  

   beds. 
  The 
  limestone 
  belt 
  is 
  interrupted 
  here 
  and 
  there 
  by 
  bands 
  

   of 
  rusty, 
  quartzose 
  schists, 
  and 
  by 
  dark 
  basic 
  hornblende 
  and 
  biotite 
  

   gneisses. 
  The 
  rusty 
  schists 
  are 
  very 
  certainly 
  a 
  part 
  of 
  the 
  same 
  

   sedimentary 
  series 
  representing 
  probably 
  old 
  sandstones, 
  while 
  the 
  

   hornblende 
  and 
  biotite 
  gneisses 
  also 
  are 
  believed 
  to 
  be 
  derived 
  from 
  

   sediments 
  of 
  the 
  nature 
  of 
  shales, 
  though 
  in 
  places 
  they 
  may 
  repre- 
  

   sent 
  altered 
  igneous 
  intrusions 
  of 
  gabbroic 
  nature. 
  The 
  gneisses 
  

   and 
  schists 
  have 
  been 
  invaded 
  by 
  a 
  red 
  granitic 
  rock, 
  with 
  pegmatitic 
  

   phases, 
  that 
  is 
  developed 
  in 
  dikes, 
  bands 
  and 
  occasionally 
  as 
  bosses 
  

   of 
  some 
  size. 
  The 
  granite 
  is 
  perhaps 
  related 
  to 
  the 
  great 
  batholiths 
  

   of 
  that 
  rock 
  which 
  are 
  found 
  in 
  the 
  interior 
  of 
  the 
  Adirondacks. 
  

   The 
  gneisses 
  have 
  been 
  so 
  injected 
  and 
  soaked 
  by 
  the 
  granite 
  that 
  

   in 
  places 
  they 
  partake 
  quite 
  as 
  much 
  of 
  igneous 
  as 
  of 
  gneissic 
  

  

  