FELDSPAR   AND    QUARTZ    DEPOSITS    OF    S.   E.   NEW    YORK.         397 
associated  not  with  the  quartz  hut  with  the  felt  1  spathic  portions  of 
the  deposit  or  may  lie  between  feldspathic  areas  and  areas  of  pure 
quartz.  In  places  the  mica  " books"  lie  with  their  sides  parallel  to 
the  quartz-feldspar  contacts,  but  more  generally  they  stand  at  right 
angles  to  these  contacts.  Few  of  them  exceed  4  to  5  inches  in  diame- 
ter and  almost  all  show  the  A  structure  and  much  " ruling."  No 
plate  mica  was  seen  and  the  total  amount  of  muscovite  is  hardly 
sufficient  to  make  it  worth  while  to  save  it  for  scrap  mica.  Being 
mainly  confined  to  rather  definite  bands  in  the  pegmatite,  most  of  it 
can  be  readily  separated  from  the  highly  feldspathic  portions.  It 
is  not  injurious  chemically -either  in  pottery  or  glass  manufacture,  but 
the  thin  elastic  plates  are  difficult  to  grind  to  the  requisite  fineness. 
Biotite  (black  mica)  occurs  in  long,  thin,  lath-shaped  crystals  some 
of  which  reach  a  length  of  several  feet  though  most  are  much  smaller. 
Black  tourmaline  is  associated  mainly  with  the  quartz,  but  is  here  and 
there  present  in  the  feldspathic  parts  of  the  pegmatite.  Magnetite 
and  garnet  are  present  in  few  places,  but  no  gem  varieties  of  tourma- 
line or  of  beryl  have  been  found.  Columbite  is  present  here  and  there 
in  small  crystals,  as  are  some  other  rare  minerals. 
Three  grades  of  feldspathic  material  are  obtained  from  these 
quarries.  "No.  1"  is  selected  from  the  purer  portions  of  the  pink- 
feldspar  masses  and  will  probably  run  considerably  less  than  5  per 
cent  in  free  quartz.  Nos.  1  and  2  of  the  table  are  said  to  be  analyses 
of  the  nearly  pure  pink  spar  and  may  be  assumed  to  represent  rather 
closely  the  composition  of  the  "No.  1"  spar,  which  is  placed  on  the 
market.  All  of  this  grade  is  shipped  in  bulk.  The  "No.  2"  feldspar- 
produced  at  this  quarry  includes  the  coarser  graphic  intergrowths  of 
pink  feldspar  (microcline)  and  quartz  and  also  includes  pegmatitic 
material  rich  in  the  white  soda  feldspar,4  albite.  This  grade  is  there- 
fore higher  in  free  quartz  and  in  soda  than  the  "No.  1."  Both  the 
"No.  1"  and  "No.  2"  grades  are  used  in  the  manufacture  of  pottery 
and  must  be  entirely  free  from  black  mica,  black  tourmaline,  garnet, 
and  other  iron-bearing  minerals.  The  "No.  2 "  spar  is  not  shipped  in 
the  crude  state,  but  is  ground  at  the  quarries.  A  "No.  3"  grade, 
made  up  mainly  of  the  albite-quartz  mixture  with  some  of  the  finer 
grained  pink  graphic  granite,  is  also  ground  at  Bedford  for  use  in  glass 
manufacture.  It  is  somewhat  higher  in  quartz  and  soda  than  the 
"No.  2,"  and  muscovite,  biotite,  and  black  tourmaline  are  not  so 
carefully  eliminated  as  in  the  "No.  1 "  and  "No.  2"  grades,  these  con- 
stituents not  being  so  injurious  in  glass  as  in  pottery  manufacture. 
Microscopic  examination  of  the  "No.  3"  spar  shows  the  presence  of 
free  quartz,  microcline  (potash  feldspar),  and  albite  (soda  feldspar). 
The  quartz  from  this  quarry  is  all  shipped  in  the  crude  state  to  the 
Bridgeport  Wood  Finishing  Company  at  New  Milford,  Conn.,  where 
it  is  ground  and  used  in  the  manufacture  of  a  wood  filler. 
Bull.  315—07 26 
