﻿REPORT 
  OF 
  THE 
  DIRECTOR 
  IO,I2 
  99 
  

  

  6 
  Years 
  ago 
  an 
  attempt 
  was 
  made 
  to 
  mine 
  the 
  garnets 
  which 
  

   occur 
  in 
  the 
  coarse, 
  feldspar, 
  biotite, 
  garnet, 
  Grenville 
  gneiss 
  two 
  

   and 
  three-fourths 
  miles 
  north 
  of 
  North 
  Creek, 
  but 
  this 
  locality 
  is 
  

   of 
  no 
  special 
  interest. 
  

  

  7 
  At 
  the 
  Hooper 
  mine 
  the 
  garnets 
  occur 
  as 
  crystals 
  (dodeca- 
  

   hedral) 
  often 
  with 
  good 
  crystal 
  boundaries, 
  up 
  to 
  an 
  inch 
  or 
  a 
  

   little 
  more 
  in 
  diameter. 
  They 
  are 
  thickly 
  scattered 
  through 
  a 
  

   medium 
  to 
  moderately 
  coarse 
  grained, 
  dark 
  to 
  light 
  gray, 
  very 
  

   gneissoid, 
  hornblendic 
  rock 
  which 
  has 
  the 
  composition 
  of 
  a 
  basic 
  

   syenite 
  or 
  an 
  acidic 
  diorite. 
  It 
  is 
  important 
  to 
  note 
  that 
  these 
  

   garnets 
  never 
  show 
  the 
  rims 
  of 
  hornblende. 
  In 
  fact 
  the 
  garnets 
  

   may 
  sometimes 
  be 
  almost 
  surrounded 
  by 
  feldspar. 
  This 
  type 
  of 
  

   occurrence 
  has 
  not 
  been 
  observed 
  on 
  a 
  large 
  scale 
  at 
  any 
  of 
  the 
  

   other 
  localities 
  within 
  the 
  county, 
  though 
  a 
  rock 
  almost. 
  exactly 
  

   like 
  it 
  occurs 
  at 
  the 
  Rogers 
  mine 
  as 
  a 
  distinct 
  zone 
  (wall 
  rock) 
  

   intermediate 
  between 
  the 
  typical 
  garnet-bearing 
  gneiss 
  and 
  the 
  

   country 
  rock 
  of 
  syenite, 
  where 
  the 
  garnet 
  rock 
  grades 
  perfectly 
  

   into 
  the 
  syenite. 
  The 
  significance 
  of 
  this 
  fact 
  will 
  be 
  explained 
  

   below. 
  

  

  The 
  deposit 
  is 
  an 
  extensive 
  one 
  and 
  a 
  very 
  large 
  mine 
  pit 
  has 
  

   been 
  opened 
  up. 
  After 
  blasting 
  out 
  the 
  rock, 
  it 
  is 
  somewhat 
  re- 
  

   duced 
  by 
  sledge 
  hammers, 
  then 
  taken 
  on 
  cars 
  to 
  the 
  mill 
  where 
  

   it 
  is 
  crushed. 
  By 
  the 
  use 
  of 
  an 
  ingenious 
  method, 
  involving 
  the 
  

   use 
  of 
  jigs, 
  the 
  garnet 
  (almandite) 
  is 
  almost 
  perfectly 
  separated 
  

   from 
  the 
  rest 
  of 
  the 
  crushed 
  rock 
  which 
  is 
  of 
  lower 
  specific 
  grav- 
  

   ity 
  than 
  the 
  garnet. 
  

  

  ORIGIN 
  OF 
  THE 
  GARNETS 
  

  

  All 
  modes 
  of 
  occurrence 
  of 
  garnets 
  observed 
  by 
  the 
  writer 
  on 
  

   the 
  North 
  Creek 
  and 
  Thirteenth 
  Lake 
  sheets 
  are 
  summarized 
  as 
  

   follows 
  : 
  

  

  1 
  As 
  crystals 
  or 
  grains 
  in 
  various 
  Grenville 
  rocks, 
  for 
  example, 
  

   the 
  garnet-pyroxene 
  gneiss 
  ; 
  the 
  hornblende-garnet 
  gneiss 
  ; 
  bio- 
  

   tite-garnet 
  gneisses, 
  etc. 
  

  

  2 
  As 
  distinct 
  crystals 
  frequently 
  occurring 
  in 
  all 
  types 
  of 
  in- 
  

   trusive 
  rocks 
  — 
  syenite, 
  granite, 
  granite 
  porphyry, 
  and 
  gabbro 
  — 
  

   except 
  the 
  diabase. 
  

  

  3 
  As 
  large 
  more 
  or 
  less 
  rounded 
  masses 
  with 
  distinct 
  horn- 
  

   blende 
  rims 
  in 
  the 
  long, 
  lenslike 
  inclusions 
  of 
  Grenville 
  horn- 
  

   blende 
  gneiss 
  in 
  syenite 
  or 
  granite. 
  

  

  4 
  

  

  