﻿REPORT 
  OF 
  THE 
  DIRECTOR 
  10,12 
  27 
  

  

  character, 
  in 
  fact, 
  all 
  gradations 
  from 
  the 
  one 
  rock 
  to 
  the 
  other 
  may 
  

   be 
  found. 
  

  

  The 
  limestones 
  and 
  schists 
  have 
  a 
  northeasterly 
  strike 
  and 
  are 
  

   upturned 
  at 
  a 
  high 
  angle. 
  The 
  limestones 
  of 
  this 
  section 
  carry 
  

   abundant 
  impurities, 
  though 
  elsewhere 
  the 
  same 
  series 
  may 
  be 
  

   nearly 
  free 
  from 
  admixture. 
  The 
  principal 
  foreign 
  minerals 
  are 
  

   silicates, 
  most 
  commonly 
  tremolite, 
  serpentine 
  and 
  talc. 
  They 
  are 
  

   either 
  scattered 
  in 
  small 
  aggregates, 
  or 
  they 
  form 
  nodules, 
  bands 
  

   and 
  veinlike 
  bodies 
  of 
  practically 
  solid 
  silicates. 
  The 
  limestones 
  

   are 
  magnesian 
  and 
  in 
  the 
  vicinity 
  of 
  the 
  ore 
  bodies 
  show 
  the 
  effects 
  

   of 
  solution 
  and 
  decomposition 
  by 
  ground 
  waters. 
  The 
  circulation 
  

   of 
  water 
  has 
  been 
  facilitated 
  apparently 
  by 
  the 
  broken, 
  shattered 
  

   nature 
  of 
  the 
  rock 
  which 
  has 
  undergone 
  severe 
  compression 
  and 
  

   more 
  or 
  less 
  differential 
  movement. 
  The 
  process 
  of 
  dolomitization 
  

   and 
  silication 
  has 
  preceded 
  for 
  the 
  most 
  part 
  the 
  introduction 
  of 
  

   the 
  ores, 
  but 
  it 
  may 
  have 
  resulted 
  from 
  the 
  same 
  agency, 
  that 
  is 
  

   by 
  the 
  transporting 
  of 
  silica 
  and 
  magnesia 
  held 
  in 
  solution 
  in 
  

   meteoric 
  or 
  deep-seated 
  waters. 
  

  

  The 
  zinc 
  blende 
  occurs 
  in 
  lenses 
  and 
  bands 
  and 
  also 
  as 
  scattered 
  

   particles 
  within 
  the 
  limestone. 
  The 
  deposits 
  have 
  the 
  appearance 
  

   of 
  replacement 
  bodies 
  rather 
  than 
  the 
  fillings 
  of 
  open 
  fissures 
  or 
  

   cavities. 
  In 
  most 
  places, 
  the 
  borders 
  of 
  the 
  richer 
  bands 
  are 
  not 
  

   sharply 
  defined, 
  but 
  are 
  in 
  the 
  nature 
  of 
  transition 
  zones 
  which 
  

   shade 
  off 
  gradually 
  into 
  the 
  limestone. 
  The 
  internal 
  structures 
  are 
  

   not 
  those 
  characteristic 
  of 
  open-fissure 
  fillings 
  as 
  there 
  is 
  no 
  appear- 
  

   ance 
  of 
  crustification 
  or 
  of 
  drusy 
  cavities 
  lined 
  with 
  crystallized 
  

   minerals. 
  The 
  compact 
  granular 
  nature 
  of 
  the 
  ore 
  furthermore 
  

   suggests 
  deposition 
  at 
  considerable 
  depth 
  and 
  under 
  pressure. 
  

  

  The 
  recent 
  development 
  work 
  at 
  Edwards 
  has 
  disclosed 
  some 
  

   interesting 
  features 
  in 
  regard 
  to 
  the 
  deposition 
  of 
  the 
  ores 
  which 
  

   are 
  the 
  subject 
  of 
  current 
  study. 
  The 
  problem 
  as 
  to 
  the 
  derivation 
  

   of 
  the 
  ores 
  seems 
  to 
  be 
  interrelated 
  with 
  the 
  partial 
  silication 
  of 
  

   the 
  limestones 
  which 
  has 
  led 
  to 
  the 
  formation, 
  in 
  the 
  first 
  place, 
  

   of 
  tremolite. 
  This 
  mineral 
  has 
  changed 
  over 
  to 
  talc, 
  more 
  or 
  less 
  

   completely, 
  through 
  normal 
  weathering 
  or, 
  which 
  appears 
  more 
  

   likely, 
  as 
  the 
  result 
  of 
  decomposition 
  brought 
  about 
  by 
  the 
  later 
  

   stages 
  of 
  the 
  underground 
  circulations 
  that 
  deposited 
  the 
  ores. 
  

   The 
  serpentine 
  in 
  larger 
  part, 
  however, 
  seems 
  to 
  have 
  formed 
  

   directly, 
  that 
  is 
  deposited 
  as 
  such 
  from 
  solution 
  and 
  not 
  originating 
  

   as 
  an 
  alteration 
  product 
  of 
  an 
  anhydrous 
  mineral. 
  Some 
  of 
  the 
  

   serpentine 
  is 
  certainly 
  later 
  than 
  the 
  metallic 
  minerals, 
  as 
  shown 
  by 
  

   the 
  veins 
  and 
  stripes 
  of 
  the 
  colloidal 
  variety 
  which 
  intersect 
  the 
  ore, 
  

  

  