82  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull. 225. 
The  granite  from  Mount  Glines,  when  examined  microscopically,  is 
found  to  contain  both  biotite  and  muscovite,  the  dark  mica  being  some- 
what altered  to  chlorite.  The  feldspars  are  only  slightly  altered 
and  the  quartz  is  clear.  Garnet,  zircon,  and  rutile  are  accessory 
constituents. 
The  northernmost  of  the  quartz  veins  prospected  on  Mount  Glines  is 
a  well-defined  fissure  vein  striking  about  N.  25°  E.  with  a  southern  dip 
varying  from  65°  to  70°.  This  trend  cuts  the  banding  of  the  granite 
at  an  angle  of  over  50°,  although  locally  the  granite  close  to  the 
fissure  exhibits  a  schistosity  parallel  to  the  vein.  In  the  case  of  both 
this  and  the  other  veins  the  evidence  all  points  to  the  occurrence  of 
two  distinct  periods  of  deformation  of  the  rock,  an  earlier,  in  which 
shearing  produced  the  gneissoid  texture  of  the  granite,  and  a  later, 
to  which  must  be  attributed  the  Assuring  of  the  granite  together  with 
the  occasional  production  of  some  degree  of  schistosity  in  the  rock 
adjacent  to  these  fissures. 
Exploration  work  has  been  done  on  the  above-mentioned  fissure 
vein,  so  that  some  of  its  characters  may  be  observed.  In  the  shaft 
(No.  1)  the  vein  is  composed  of  quartz,  together  with  varying  amounts 
of  talcose  material.  This  material  when  studied  under  the  microscope 
is  seen  to  be  simply  altered  wall  rock.  The  feldspar  is  almost  com- 
pletely altered,  probably  by  hydration,  into  masses  of  kaolin  and 
sericite.  The  quartz  that  remains  in  the  original  grains  is  clouded 
with  lines  of  minute  cavities.  The  muscovite  is  present  in  this 
altered  phase  of  the  granite,  but  its  flakes  have  been  bent  by  the  move- 
ment which  the  rock  has  evidently  experienced.  Small  veinlets  of 
clear,  secondary  quartz  cross  this  material  in  all  directions. 
The  gangue  of  the  vein  is  largely  white  quartz,  clear  in  color  and 
compact  in  texture.  With  this  is  associated  the  stringers  of  greenish 
material  already  described.  This  occurs  mostly  near  the  walls,  and 
from  its  mixture  with  quartz  gives  the  vein  in  places  the  appearance 
of  pegmatite,  this  being  a  structural  resemblance  only,  as  the  feldspar : 
characteristic  of  pegmatite  veins  is  lacking  here.  The  sulphides, 
galena  and  pyrite,  occur  in  scattered  bunches  in  the  vein,  which  varies 
from  4i  feet  to  less  than  2J  feet. 
While  this  vein  is  plainly  a  fissure  vein,  its  walls  are  not  at  all  points 
well  defined,  owing  to  the  occurrence  of  other  fracture  planes  which 
intersect  the  main  fissure  walls  at  slight  angles  and  cause  the  irregu~i 
larities  in  width  of  the  vein  mentioned  above.  The  walls  are  not 
slickensided  and  in  places  the  distinction  between  vein  material  and 
wall  is  obscure.  There  is  therefore  in  this  vein  no  evidence  of  move- 
ment later  than  that  at  the  time  of  the  formation  of  the  fissure,  when) 
the  masses  of  granite  described  above  were  separated  from  the  walls 
and  more  or  less  crushed  and  then  incorporated  in  the  vein  filling. 
Seventy -five  feet  lower  on  the  slope  a  tunnel  has  been  driven  in  on 
i 
