﻿i^ 
  LIBRARY! 
  

  

  JOURNAL 
  

  

  OF 
  THE 
  

  

  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  

  

  Vol.. 
  12 
  December 
  4, 
  1922 
  No. 
  20 
  

  

  GEOLOGY. 
  — 
  Geology 
  of 
  a 
  vein 
  occurrence 
  of 
  rutile-ilmenite 
  in 
  a 
  new 
  

   locality.^ 
  Thomas 
  L. 
  Watson, 
  University 
  of 
  Virginia. 
  

  

  INTRODUCTION 
  

  

  In 
  each 
  of 
  the 
  several 
  known 
  world 
  areas 
  of 
  commercial 
  rutile, 
  the 
  

   mineral 
  occurs 
  as 
  a 
  primary 
  constituent 
  of 
  some 
  type 
  of 
  igneous 
  rock, 
  

   formed 
  either 
  as 
  a 
  product 
  of 
  crystallization 
  from 
  a 
  molten 
  magma 
  or 
  as 
  

   the 
  result 
  of 
  pneumatolysis. 
  As 
  a 
  primary 
  mineral 
  formed 
  under 
  

   igneous 
  conditions, 
  rutile 
  is 
  a 
  high 
  temperature 
  product, 
  but 
  prob- 
  

   ably 
  not 
  in 
  all 
  cases 
  necessarily 
  accompanied 
  by 
  high 
  pressure. 
  Ac- 
  

   curate 
  measurements 
  by 
  the 
  Bureau 
  of 
  Standards, 
  Washington, 
  D. 
  C, 
  

   on 
  carefully 
  prepared 
  specimens 
  of 
  rutile 
  separated 
  from 
  the 
  igneous 
  

   rocks, 
  syenite 
  and 
  nelsonite, 
  of 
  Nelson 
  County, 
  Virginia, 
  gave 
  1690° 
  C. 
  

   (syenite) 
  and 
  1700° 
  C. 
  (nelsonite).- 
  

  

  The 
  occurrence 
  of 
  primary 
  coarse 
  rutile 
  in 
  veins 
  and 
  pegmatites 
  

   is 
  well 
  known 
  but 
  not 
  common. 
  The 
  two 
  occurrences 
  are 
  closely 
  

   related 
  genetically, 
  and 
  in 
  each, 
  rutile 
  has 
  developed 
  as 
  a 
  primary 
  

   mineral 
  under 
  conditions 
  of 
  high 
  temperature. 
  

  

  Of 
  the 
  vein 
  occurrences 
  of 
  primary 
  rutile, 
  the 
  mineralogic 
  types, 
  

   ru 
  tile-bearing 
  apatite 
  veins, 
  with 
  or 
  without 
  scapolite, 
  and 
  rutile- 
  

   bearing 
  quartz 
  veins, 
  with 
  or 
  without 
  ilmenite, 
  seem 
  well 
  established. 
  

   Others 
  are 
  known, 
  especially 
  some 
  metalliferous 
  veins, 
  in 
  which 
  

   rutile 
  occurs 
  as 
  a 
  minor 
  constituent. 
  

  

  Representatives 
  of 
  the 
  apatite 
  vein 
  type 
  in 
  Norway 
  and 
  Sweden 
  have 
  

   been 
  described 
  by 
  Vogt^ 
  and 
  are 
  regarded 
  by 
  him 
  to 
  be 
  of 
  pneumatolytic 
  

   character. 
  In 
  this 
  type 
  rutile 
  is 
  associated 
  with 
  the 
  titanium 
  minerals, 
  

   ilmenite 
  and 
  titanite. 
  Important 
  rutile-bearing 
  apatite 
  bodies 
  with 
  

   or 
  without 
  ilmenite 
  and 
  known 
  as 
  the 
  rutile 
  variety 
  of 
  the 
  igneous 
  

   rock 
  nelsonite 
  occur 
  in 
  Nelson 
  County, 
  Virginia. 
  These 
  have 
  been 
  

  

  1 
  Received 
  October 
  19, 
  1922. 
  

  

  2 
  Watson, 
  Thomas 
  L. 
  and 
  Taber, 
  S. 
  Va. 
  Geol. 
  Survey 
  Bull. 
  Ul-A: 
  154. 
  1913. 
  

  

  3 
  VOGT, 
  J. 
  H. 
  L. 
  Genesis 
  of 
  Ore 
  Deposits. 
  Trans. 
  Amer. 
  Inst. 
  Min. 
  Engrs., 
  646. 
  1901. 
  

  

  447 
  

  

  