﻿54 
  TWENTY-FIRST 
  REPORT 
  ON 
  THE 
  STATE 
  CABINET. 
  

  

  475, 
  are 
  generally 
  granitoid 
  or 
  gneissoid 
  in 
  structure. 
  They 
  are 
  

   sometimes 
  fine 
  grained, 
  and 
  at 
  other 
  times 
  made 
  up 
  of 
  crystalline 
  

   elements 
  from 
  two-tenths 
  to 
  five-tenths 
  of 
  an 
  inch 
  in 
  diameter. 
  

   They 
  occasionally 
  assume 
  a 
  great 
  thickness, 
  and 
  are 
  then 
  often 
  

   interstratifiecl 
  with 
  beds 
  of 
  granitoid 
  orthoclase 
  gneiss, 
  into 
  which 
  

   the 
  quartzo-felspathic 
  pyroxenites 
  pass 
  by 
  a 
  gradual 
  disappearance 
  

   of 
  the 
  pyroxene. 
  These 
  peculiar 
  strata, 
  which 
  contain 
  at 
  the 
  same 
  

   time 
  the 
  minerals 
  of 
  the 
  associated 
  gneiss 
  and 
  of 
  the 
  limestones, 
  

   may 
  thus 
  be 
  looked 
  upon 
  as 
  beds 
  of 
  passage 
  between 
  the 
  two 
  

   rocks. 
  Their 
  mineral 
  species 
  and 
  varieties, 
  so 
  far 
  as 
  my 
  observa- 
  

   tions 
  go, 
  are, 
  identical 
  with 
  those 
  of 
  the 
  limestones 
  themselves. 
  

   It 
  should 
  be 
  remembered 
  that, 
  besides 
  the 
  minerals 
  already 
  men- 
  

   tioned 
  as 
  predominating 
  in 
  these 
  strata, 
  other 
  species 
  character- 
  

   istic 
  of 
  the 
  limestones, 
  such 
  as 
  serpentine 
  and 
  magnetite, 
  sometimes 
  

   make 
  up 
  by 
  themselves 
  great 
  beds 
  in 
  these 
  intermediate 
  or 
  tran- 
  

   sition 
  strata, 
  which, 
  from 
  their 
  mineralogical 
  relations, 
  may 
  all 
  be 
  

   looked 
  upon 
  as 
  related 
  to 
  the 
  accompanying 
  limestones. 
  In 
  some 
  

   districts, 
  however, 
  hornblende 
  predominates 
  over 
  the 
  pyroxene, 
  

   and 
  gives 
  rise 
  to 
  beds 
  of 
  pure 
  hornblende 
  rock, 
  or 
  amphibolite, 
  

   sometimes 
  schistose, 
  and 
  to 
  compound 
  rocks, 
  such 
  as 
  diorite 
  and 
  

   hornblendic 
  gneiss, 
  so 
  that 
  each 
  group 
  of 
  limestones, 
  with 
  its 
  

   attendant 
  pyroxenites, 
  amphibolites, 
  serpentines, 
  magnetites, 
  etc., 
  

   may 
  be 
  considered 
  as 
  characterizing 
  an 
  epoch 
  in 
  the 
  geological 
  

   period 
  to 
  which 
  it 
  belongs. 
  

  

  Each 
  one 
  of 
  the 
  three 
  great 
  limestone 
  formations 
  which 
  have 
  

   been 
  recognized 
  in 
  the 
  Laurentian 
  system 
  on 
  the 
  Ottawa, 
  appears 
  

   to 
  be 
  associated 
  with 
  these 
  related 
  rocks, 
  which 
  are, 
  however, 
  in 
  

   some 
  parts, 
  developed 
  to 
  a 
  great 
  extent, 
  and 
  in 
  others 
  are 
  com- 
  

   paratively 
  unimportant 
  in 
  volume. 
  These 
  limestone 
  groups, 
  as 
  

   we 
  may 
  hereafter 
  designate 
  the 
  limestones 
  with 
  their 
  attendant 
  

   rocks, 
  appear 
  to 
  be 
  the 
  parts 
  of 
  the 
  system 
  to 
  which 
  the 
  principal 
  

   economic 
  minerals 
  belong. 
  The 
  ores 
  of 
  iron, 
  copper, 
  nickel 
  and 
  

   cobalt, 
  the 
  apatite, 
  mica 
  and 
  plumbago, 
  as 
  well 
  as 
  the 
  serpentines 
  

   and 
  the 
  marbles 
  of 
  the 
  great 
  Lower 
  Laurentian 
  series, 
  belong, 
  so 
  

   far 
  as 
  yet 
  known, 
  to 
  the 
  limestone 
  groups. 
  

  

  The 
  Labrador 
  or 
  Upper 
  Laurentian 
  series 
  includes 
  one, 
  and 
  per- 
  

   haps 
  more 
  limestone 
  bands, 
  which, 
  so 
  far 
  as 
  ascertained, 
  present 
  

   the 
  same 
  mineralogical 
  accompaniments 
  as 
  the 
  limestone 
  forma- 
  

   tions 
  of 
  the 
  Lower 
  Laurentian. 
  

  

  Mineral 
  Veins. 
  

   We 
  may 
  now 
  consider 
  the 
  mineral 
  veins 
  which 
  traverse 
  the 
  

  

  