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  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  igneous 
  magna, 
  quite 
  similar 
  in 
  general 
  features 
  to 
  the 
  titaniferous 
  

   magnetites 
  that 
  occur 
  in 
  gabbros 
  and 
  anorthosites. 
  Some 
  of 
  the 
  

   deposits 
  were 
  worked 
  in 
  the 
  early 
  days 
  for 
  iron 
  ore, 
  but 
  the 
  ma- 
  

   terial 
  proved 
  too 
  refractory 
  for 
  successful 
  treatment 
  in 
  the 
  fur- 
  

   nace. 
  The 
  emery 
  is 
  not 
  regarded 
  in 
  the 
  trade 
  as 
  equal 
  to 
  the 
  

   Grecian 
  or 
  Turkish 
  product, 
  though 
  it 
  is 
  said 
  to 
  be 
  very 
  serviceable 
  

   when 
  made 
  into 
  wheels 
  with 
  a 
  vitreous 
  bond. 
  

  

  FELDSPAR 
  

  

  The 
  small 
  demand 
  for 
  feldspar 
  among 
  pottery 
  manufacturers 
  

   last 
  year 
  was 
  reflected 
  in 
  a 
  decreased 
  output 
  of 
  the 
  better 
  grades 
  

   of 
  the 
  mineral, 
  i. 
  e. 
  the 
  potash 
  feldspars 
  free 
  from 
  iron 
  or 
  other 
  

   obnoxious 
  impurities. 
  On 
  the 
  other 
  hand, 
  the 
  production 
  of 
  un- 
  

   selected 
  feldspar, 
  such 
  as 
  finds 
  employment 
  for 
  roofing 
  material, 
  

   poultry 
  grit, 
  abrasive 
  purposes, 
  etc. 
  showed 
  a 
  substantial 
  gain 
  over 
  

   the 
  quantity 
  reported 
  in 
  1907. 
  

  

  The 
  occurrence 
  of 
  pegmatite, 
  from 
  which 
  feldspar 
  is 
  obtained, 
  

   is 
  limited 
  in 
  this 
  State 
  to 
  the 
  Adirondack 
  Precambric 
  area 
  and 
  the 
  

   southeastern 
  region 
  of 
  crystalline 
  rocks. 
  The 
  pegmatite 
  forms 
  dikes, 
  

   sheetlike 
  masses 
  or 
  irregular 
  bodies, 
  usually 
  in 
  association 
  with 
  

   larger 
  masses 
  of 
  allied 
  intrusive 
  rocks 
  of 
  which 
  it 
  often 
  consti- 
  

   tutes 
  but 
  a 
  coarser 
  phase. 
  Most 
  occurrences 
  have 
  the 
  composition 
  

   of 
  granite, 
  containing 
  besides 
  feldspar 
  a 
  considerable 
  proportion 
  

   of 
  quartz 
  and 
  smaller 
  amounts 
  of 
  mica, 
  hornblende 
  or 
  rarely 
  

   pyroxene. 
  The 
  presence 
  of 
  iron-bearing 
  minerals 
  has 
  an 
  impor- 
  

   tant 
  bearing 
  upon 
  the 
  quality 
  of 
  the 
  product, 
  since 
  for 
  pottery 
  

   purposes 
  it 
  is 
  absolutely 
  essential 
  that 
  the 
  feldspar 
  contain 
  nothing 
  

   more 
  than 
  a 
  trace 
  of 
  iron. 
  When 
  occurring 
  in 
  segregated 
  particles 
  

   their 
  elimination 
  can 
  be 
  effected 
  sometimes 
  by 
  careful 
  cobbing. 
  In 
  

   addition 
  to 
  those 
  already 
  enumerated, 
  pyrite, 
  magnetite 
  and 
  tour- 
  

   malin 
  are 
  among 
  the 
  iron-bearing 
  minerals 
  commonly 
  found 
  in 
  

   pegmatite. 
  For 
  pottery 
  uses 
  the 
  potash 
  feldspars 
  (microcline 
  and 
  

   orthoclase) 
  are 
  the 
  only 
  ones 
  produced 
  in 
  New 
  York 
  State 
  and 
  

   they 
  seem 
  to 
  have 
  the 
  preference 
  in 
  that 
  trade, 
  though 
  for 
  what 
  

   reason 
  is 
  not 
  well 
  understood. 
  The 
  plagioclase 
  feldspars 
  are 
  found 
  

   in 
  the 
  Adirondack 
  pegmatites 
  which 
  are 
  chiefly'quarried 
  for 
  roofing 
  

   material. 
  

  

  The 
  quarries 
  now 
  active 
  in 
  the 
  State 
  are 
  situated 
  in 
  Westchester, 
  

   Essex 
  and 
  Saratoga 
  counties. 
  Those 
  near 
  'Bedford, 
  Westchester 
  

   CO. 
  produce 
  most 
  of 
  the 
  pottery 
  feldspar. 
  They 
  are 
  operated 
  by 
  

   P. 
  H. 
  Kinkel's 
  Sons 
  who 
  grind 
  a 
  large 
  part 
  of 
  the 
  output 
  before 
  

  

  