﻿Judcl 
  and 
  Hidden 
  — 
  Ruhy 
  in 
  North 
  Carolina. 
  37T 
  

  

  The 
  chief 
  ferro-magnesian 
  silicates 
  are 
  hornblende 
  (a 
  variety 
  

   rich 
  in 
  soda) 
  and 
  bronzite 
  (in 
  clear 
  transparent 
  masses 
  suitable 
  

   for 
  gems). 
  

  

  Among 
  the 
  accompanying 
  minerals 
  are 
  : 
  zircon 
  (with 
  the 
  

   variety 
  cyrtolite), 
  monazite 
  (the 
  macroscopic 
  brown 
  and 
  green 
  

   varieties 
  appear 
  to 
  be 
  rare, 
  but 
  a 
  minute 
  brilliant 
  yellow 
  granu- 
  

   lar 
  variety 
  with 
  only 
  0'03 
  per 
  cent 
  of 
  thoria 
  abounds^ 
  rutile 
  

   and 
  menaccanite. 
  

  

  Among 
  metallic 
  minerals 
  the 
  chief 
  are 
  pyrite, 
  chalcopyrite, 
  

   nickeliferous 
  pyrrhotite, 
  blende, 
  sperrylite, 
  and 
  gold.^ 
  

  

  Conclusions. 
  

  

  Corundum 
  has 
  now 
  been 
  shown 
  to 
  occur 
  in 
  JN'orth 
  Carolina 
  

   and 
  the 
  adjoining 
  States 
  in 
  three 
  different 
  forms 
  : 
  

  

  (1) 
  In 
  the 
  ordinary 
  crystalline 
  schists 
  of 
  the 
  district, 
  long 
  

   prismatic 
  crystals, 
  usually 
  of 
  gray, 
  pink 
  and 
  blue 
  tints, 
  occur. 
  

  

  (2) 
  In 
  the 
  peridotites 
  (d 
  unites, 
  etc.), 
  intrusive 
  in 
  the 
  crystal- 
  

   line 
  schists, 
  and 
  especially 
  in 
  and 
  near 
  the 
  zones 
  of 
  contact, 
  

   crystals, 
  some 
  of 
  very 
  great 
  size 
  and 
  of 
  great 
  variety 
  of 
  color, 
  

   but 
  seldom 
  or 
  never 
  clear 
  and 
  translucent, 
  are 
  found. 
  

  

  (3) 
  In 
  certain 
  garnet-bearing 
  basic 
  rocks 
  at 
  Cowee 
  Creek, 
  

   small 
  tabular 
  and 
  short 
  prismatic 
  crystals 
  are 
  abundant, 
  and 
  

   these 
  very 
  frequently 
  exhibit 
  the 
  transparency 
  and 
  color 
  of 
  the 
  

   true 
  ruby. 
  

  

  Dr. 
  Pratt, 
  in 
  his 
  recent 
  discussion 
  on 
  the 
  second 
  of 
  these 
  

   modes 
  of 
  occurrence 
  of 
  corundum, 
  has 
  shown 
  grounds 
  for 
  con- 
  

   cluding 
  that 
  the 
  alumina 
  of 
  the 
  corundum 
  was 
  in 
  these 
  cases 
  

   originally 
  dissolved 
  in 
  the 
  fused 
  basic 
  magma 
  of 
  the 
  peridotites, 
  

   and 
  that 
  crystals 
  of 
  corundum 
  separated 
  from 
  that 
  magma 
  in 
  

   the 
  manner 
  which 
  has 
  been 
  illustrated 
  by 
  the 
  interesting 
  experi- 
  

   ments 
  of 
  Morozewicz.f 
  

  

  The 
  tabular 
  form 
  of 
  the 
  crystals 
  of 
  corundum 
  has 
  been 
  

   shown 
  by 
  Lagorio;]: 
  in 
  his 
  well-known 
  memoir 
  on 
  the 
  subject 
  to 
  

   be 
  characteristic 
  of 
  corundum 
  found 
  in 
  igneous 
  rocks. 
  And 
  

   this 
  conclusion 
  has 
  been 
  supported 
  by 
  the 
  researches 
  of 
  Prof. 
  

   L. 
  Y. 
  Pirsson 
  and 
  Dr. 
  Pratt.g 
  

  

  If 
  we 
  compare 
  the 
  forms 
  figured 
  by 
  Dr. 
  Pratt 
  in 
  the 
  

   appendix 
  to 
  this 
  paper 
  with 
  those 
  described 
  by 
  him 
  from 
  Yogo 
  

   Gulch, 
  the 
  resemblance 
  will 
  be 
  seen 
  to 
  be 
  very 
  striking. 
  But 
  

  

  * 
  For 
  fuller 
  details 
  concerning 
  these 
  accompanying 
  minerals 
  with 
  analyses 
  con- 
  

   sult 
  a 
  paper 
  "On 
  the 
  Associated 
  Minerals 
  of 
  Rhodolite," 
  by 
  W. 
  E. 
  Hidden 
  and 
  

   J. 
  H. 
  Pratt, 
  this 
  Journal, 
  lY, 
  vol. 
  vi, 
  1898, 
  pp. 
  463-468. 
  

  

  f 
  Zeitschr. 
  Kryst., 
  vol. 
  xxiv, 
  1895. 
  p. 
  281, 
  and 
  Tscherm. 
  Min. 
  und 
  Petr, 
  Mitt. 
  vol. 
  

   xviii. 
  1898, 
  pp. 
  1-90, 
  105-240. 
  

  

  X 
  Zeitschr. 
  Kryst., 
  vol. 
  xxiv, 
  1895, 
  p. 
  285. 
  

  

  ^"Corundum-bearing 
  Eock 
  from 
  Yogo 
  Gulch, 
  Montana," 
  by 
  L. 
  Y. 
  Pirsson, 
  

   this 
  Journal, 
  lY, 
  vol. 
  iv, 
  1897, 
  p. 
  421; 
  "Crystallography 
  of 
  the 
  Montana 
  

   Sapphires," 
  by 
  J. 
  H. 
  Pratt, 
  ibid., 
  p. 
  424. 
  

  

  