418  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1906,  PART    7. 
shallow  shafts,  and  small  crooked  tunnels,  scarcely  large  enough  for  a 
man  to  work  in.  The  term  might  also  be  appropriately  used  to 
describe  the  irregular  stopes  made  by  "jayhawkers"  and  petty 
leasers  in  underground  workings.  These  people  cut  down  all  the 
niica-bearing  material  available  and  leave  the  waste  to  accumulate 
in  the  mine  until  further  work  is  difficult  or  impossible. 
Some  of  the  mines  are  located  in  rather  inaccessible  places,  to 
which  tools  and  provisions  have  to  be  packed  on  men's  shoulders, 
and  from  which  the  mica  is  brought  away  by  the  same  methods.  As 
the  needs  of  the  mountaineer  and  the  variety  of  tools  required  are 
small,  even  these  mines  can  often  be  operated  at  a  profit. 
At  most  of  the  mines  blacksmith  forges  of  suitable  size  to  meet  the 
requirements  are  set  up  so  that  drills  and  tools  can  be  sharpened  and 
other  shop  work  done.  Each  mine  generally  has  a  storage  bin  or 
house  where  the  mica  is  kept  and  sorted  over  before  selling  or  hauling 
to  trimming  establishments.  At  some  mines  the  output  is  sold  in  the 
rough.  At  others  it  is  split  and  sized  either  with  or  without  trimming 
off  the  rough  corners  and  edges.  Part  of  the  production  is  shipped 
to  the  manufacturers  after  rough  trimming  and  sizing,  and  the 
remainder  is  prepared  for  the4  market  in  local  establishments  by  cut- 
ting into  patterns  and  punching.  The  waste  from  the  mines  and  scrap 
from  the  cutting  houses  is  ground  in  local  mills  or  shipped  to  mills 
outside  of  the  State. 
ORIGIN. 
Mica  of  commercial  size  in  North  Carolina  occurs  only  in  pegmatite. 
It  is  uncertain  whet  her  this  rock  should  be  classed  with  dikes  or  veins, 
h  is  probable  thai  some  bodies  are  true  dikes,  whereas  others  may  be 
vein  formations.  A  large  number  fall  into  an  intermediate  class,  of 
which  it  is  not  likely  that  a  reference  to  either  origin  can  ever  be  made. 
There  seems  to  be  no  reason  against  accepting  an  intrusive  origin  for 
the  majority  of  those  pegmatites  which  have  a  typical  granitic  tex- 
ture and  in  which  none  of  the  constituent  minerals  are  separated  out 
in  sheet  like  masses  parallel  to  the  walls,  especially  those  that  are  more 
persistent  in  extent  in  regions  where  granite  intrusions  are  of  large 
size  or  plentiful.  On  the  other  hand,  it  does  not  seem  reasonable  to 
consider  certain  forms  of  pegmatite,  occurring  in  the  region  studied, 
as  true  igneous  injections.  In  this  statement  are  included  such 
pegmatites  as  are  illustrated  in  figs.  16  and  17  and  probably  also  in 
fig.  15.     In  each  of  these  masses  banding  is  evident. 
Fig.  16  represents  a  vein  cutting  a  mass  of  coarse  granite  or  peg- 
matite in  a  region  of  granite  intrusions.  The  vein  is  composed  of  the 
same  minerals,  coarsely  crystallized,  as  in  pegmatite,  and  is  itself 
pegmatite.  It  is  evident  that  there  have  been  several  stages,  in  its 
formation.     Apparently  the  mica-feldspar  bands  along  the  walls  were 
