﻿448 
  JOURNAL 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOI^. 
  12, 
  NO. 
  20 
  

  

  described 
  by 
  Watson 
  and 
  Taber/ 
  who 
  regard 
  them 
  as 
  igneous 
  dikes 
  

   and 
  not 
  true 
  veins. 
  

  

  The 
  rutile-bearing 
  quartz 
  vein 
  type, 
  with 
  or 
  without 
  ilmenite, 
  is 
  

   represented 
  in 
  the 
  Piedmont 
  Plateau 
  province 
  of 
  the 
  southern 
  Ap- 
  

   palachians, 
  especially 
  Virginia, 
  where 
  several 
  occurrences 
  are 
  known. 
  

   The 
  known 
  occurrences 
  of 
  this 
  type 
  of 
  vein 
  are 
  characterized 
  by 
  the 
  

   absence 
  of 
  all 
  minerals 
  except 
  quartz 
  and 
  rutile 
  and, 
  in 
  some 
  instances, 
  

   ilmenite. 
  The 
  purpose 
  of 
  this 
  paper 
  is 
  to 
  describe 
  one 
  of 
  the 
  more 
  im- 
  

   portant 
  occurrences 
  of 
  this 
  type. 
  

  

  The 
  older 
  gneisses 
  and 
  schists 
  of 
  the 
  Piedmont 
  province 
  of 
  the 
  south- 
  

   eastern 
  Atlantic 
  States 
  have 
  been 
  freely 
  injected 
  in 
  places 
  by 
  granite 
  

   pegmatites 
  and 
  quartz 
  veins, 
  which 
  both 
  conform 
  with 
  and 
  cut 
  across 
  

   the 
  structure 
  of 
  the 
  rocks. 
  All 
  gradations 
  between 
  typical 
  granite 
  

   pegmatites, 
  with 
  or 
  without 
  rarer 
  minerals, 
  and 
  quartz 
  veins, 
  with 
  

   or 
  without 
  other 
  minerals, 
  exist 
  and 
  can 
  be 
  traced. 
  Black 
  tourmaline 
  

   is 
  a 
  frequent 
  mineral 
  in 
  many 
  of 
  the 
  quartz 
  veins 
  of 
  the 
  Virginia 
  Pied- 
  

   mont 
  province, 
  but 
  so 
  far 
  as 
  the 
  writer 
  is 
  aware 
  it 
  does 
  not 
  occur 
  in 
  

   the 
  rutile-bearing 
  type 
  of 
  quartz 
  vein. 
  

  

  The 
  pegmatite 
  occurrence 
  of 
  rutile 
  is 
  likewise 
  represented 
  in 
  the 
  

   old 
  gneiss-schist 
  complex 
  of 
  the 
  Virginia 
  Piedmont 
  Plateau 
  province. 
  

   One 
  of 
  the 
  most 
  important 
  of 
  these 
  from 
  the 
  standpoint 
  of 
  probable 
  

   commercial 
  rutile 
  is 
  an 
  area^ 
  in 
  Goochland 
  and 
  Hanover 
  counties, 
  

   Virginia, 
  near 
  but 
  within 
  the 
  eastern 
  border 
  of 
  the 
  Piedmont 
  province. 
  

   Here 
  granite-gneisses 
  are 
  injected 
  by 
  granite 
  pegmatites 
  which 
  conform 
  

   as 
  a 
  rule, 
  with 
  the 
  gneiss 
  structure. 
  Some 
  of 
  these 
  carry 
  rutile 
  as 
  a 
  

   primary 
  constituent 
  in 
  grains 
  and 
  masses 
  of 
  many 
  pounds 
  in 
  weight. 
  

   The 
  rutile 
  is 
  frequently 
  intergrown 
  with 
  ilmenite, 
  but 
  there 
  is 
  a 
  singu- 
  

   lar 
  absence 
  of 
  other 
  minerals 
  save 
  the 
  common 
  rock-making 
  silicates 
  

   of 
  granite 
  pegmatites. 
  Unlike 
  the 
  rutile-ilmenite 
  intergrowths 
  of 
  the 
  

   Franklin 
  County, 
  Virginia, 
  quartz 
  vein 
  described 
  below 
  there 
  is 
  gen- 
  

   eral 
  absence 
  of 
  crystal 
  form 
  in 
  the 
  titanium 
  minerals 
  occurring 
  in 
  the 
  

   pegmatites 
  of 
  Goochland 
  and 
  Hanover 
  counties. 
  

  

  Recently 
  rutile 
  has 
  been 
  noted 
  by 
  the 
  writer 
  in 
  one 
  of 
  the 
  ex- 
  

   tensively 
  worked 
  pegmatites 
  of 
  the 
  Amelia 
  County, 
  Virginia, 
  area, 
  

   so 
  well 
  known 
  to 
  mineralogists 
  for 
  the 
  large 
  number 
  of 
  rarer 
  minerals 
  

   found 
  in 
  them. 
  Part 
  of 
  a 
  prismatic 
  crystal 
  of 
  rutile 
  weighing 
  1 
  pound 
  

  

  « 
  Watson, 
  Thomas 
  L. 
  and 
  Taber, 
  S. 
  Va. 
  Geol. 
  Survey 
  Bull. 
  III-A: 
  100-155. 
  1913. 
  

   6 
  Watson, 
  Thomas 
  L. 
  and 
  Taber, 
  S. 
  Va. 
  Geol. 
  Survey 
  Bull. 
  III-A: 
  248-261. 
  1913. 
  

   Hess, 
  Frank 
  L. 
  Mining 
  World 
  33: 
  305-307. 
  1910. 
  

  

  