MICA    DEPOSITS    OF    WESTERN    NORTH    CAROLINA.  407 
found  to  be  clear  and  of  light  color.  Where  the  pegmatite  is  closely 
associated  with  or  occurs  in  granite  with  a  paucity  of  the  ferromagne- 
sian  minerals,  the  mica  is  generally  of  dark  color  and  much  of  it 
" specked."  The  true  color  of  mica  is  best  observed  in  sheets  from 
one-sixteenth  to  one-fourth  inch  in  thickness  when  examined  in 
transmitted  light. 
The  mica  occupies  various  positions  in  the  pegmatite.  Where  the 
rock  has  a  typical  granitic  texture,  the  mica  may  be  found  evenly 
distributed  through  it.  More  commonly  the  larger  crystals  will  be 
found  either  in  clusters  at  intervals  through  the  "  vein,"  in  places  con- 
nected by  streaks  of  small  crystals,  or  collected  along  one  or  both 
walls  of  the  pegmatite,  with  some  of  the  crystals  partly  embedded  in 
the  wall  rock.  Where  there  is  a  quartz  streak  within  the  pegmatite, 
the  mica  occurs  on  either  or  both  sides  of  it,  being  in  places  partly 
embedded  in  the  quartz  or  occupying  any  of  the  positions  noted  above 
in  the  remaining  portion  of  the  pegmatite,  which  generally  is  com- 
posed largely  of  feldspar. 
ASSOCIATED  MINERALS. 
Over  forty  different  minerals  have  been  found  in  the  pegmatites  of 
North  Carolina.0  Besides  muscovite  mica,  several  others  of  com- 
mercial importance  are  found,  including  quartz  in  large  masses, 
feldspar  in  considerable  quantity,  kaolin  in  large  deposits,  beryl  of 
several  gem  varieties,  zircon,  uranium  minerals  carrying  radium, 
samarskite,  and  columbite.  Most  of  the  rare  minerals,  as  gem  beryl, 
columbite,  those  of  uranium,  etc.,  are  found  in  Mitchell  and  Yancey 
counties;  though  beryl  of  gem  quality  is  found  also  in  many  other 
counties.  The  beryls  from  the  pegmatites  have  furnished  handsome 
gems,  as  emerald,  aquamarine  (sea  green  and  blue),  and  the  golden 
variety.  The  potash  feldspar  removed  in  mica  mining  should  prove 
of  value  if  shipped  to  manufacturers.  Kaolin  results  from  the  decom- 
position of  the  feldspar  of  the  pegmatites  by  weathering.  In  the 
majority  of  the  pegmatites  of  North  Carolina  that  have  been  opened 
for  their  valuable  minerals  the  feldspar  is  found  to  have  partially  or 
entirely  altered  to  kaolin  from  the  outcrop  down  to  depths  varying 
from  a  few  to  100  feet  or  more.  In  this  way  valuable  deposits  of 
kaolin  have  formed. 
DESCRIPTION   OF   MINES. 
MILTON    ENGLISH    AND    NEIGHBORING    MINES. 
The  Milton  English  mine,  about  1  mile  northeast  of  Plumtree, 
Mitchell  County,  furnishes  one  of  the  most  typical  examples  of  peg- 
matite  lens  formation   known.     The   pegmatite   lies   in   one   of   the 
a  Pratt,  J.  H.,  Mining  industry  in  North  Carolina  in  1901:  Economic  Paper  North  Carolina  Geol. 
Survey  No.  6,  1902. 
