﻿Warren, 
  Allan 
  and 
  Conner 
  — 
  A 
  Titaniferous 
  Augite. 
  75 
  

  

  Art. 
  IX. 
  — 
  A 
  Titaniferous 
  Augite 
  from 
  Ice 
  River, 
  British 
  

   Columbia; 
  by 
  Charles 
  H. 
  Warren 
  and 
  John 
  A. 
  Allan, 
  

   with 
  a 
  Chemical 
  Analysis 
  by 
  M. 
  F. 
  Conner. 
  

  

  In 
  the 
  course 
  of 
  an 
  extended 
  study 
  of 
  the 
  nephelite-syenites 
  

   and 
  their 
  associated 
  rocks, 
  occurring 
  in 
  the 
  Ice 
  River 
  District 
  

   of 
  British 
  Columbia,* 
  one 
  of 
  the 
  authors 
  (Allan) 
  has 
  described 
  

   several 
  melanocratic 
  types 
  of 
  rock, 
  occurring 
  as 
  basic 
  differ- 
  

   entiates 
  from 
  the 
  nephelite-syenite 
  magma, 
  particularly 
  near 
  

   the 
  contacts. 
  In 
  several 
  of 
  these 
  (jacupirangites, 
  etc.), 
  a 
  rather 
  

   strongly 
  pleochroic 
  pyroxene, 
  containing 
  abundant, 
  rod-like, 
  

   black 
  inclusions, 
  was 
  noted. 
  On 
  study, 
  it 
  was 
  found 
  to 
  be 
  an 
  

   augite 
  of 
  somewhat 
  unusual 
  characteristics, 
  and 
  it 
  has 
  accord- 
  

   ingly 
  been 
  thought 
  well 
  to 
  publish 
  a 
  brief 
  description 
  of 
  it. 
  

  

  In 
  several 
  specimens, 
  representing 
  the 
  melanocratic 
  types, 
  

   this 
  augite 
  was 
  noted, 
  frequently 
  associated 
  with 
  a 
  pale 
  green, 
  

   augitic 
  pyroxene.f 
  It 
  was 
  also 
  commonly 
  associated 
  with 
  a 
  

   brown, 
  barkevikitic 
  hornblende, 
  biotite, 
  nephelite, 
  apatite, 
  

   sphene 
  and 
  ilmenite. 
  Fortunately, 
  one 
  specimen 
  was 
  found 
  

   which 
  consisted 
  very 
  largely 
  of 
  the 
  augite 
  — 
  an 
  augitite, 
  in 
  

   fact 
  — 
  and 
  from 
  this 
  specimen 
  material, 
  suitable 
  for 
  micro- 
  

   scopic 
  study 
  and 
  chemical 
  analysis, 
  was 
  obtained. 
  

  

  In 
  the 
  specimen 
  alluded 
  to, 
  the 
  augite 
  was 
  associated 
  with 
  a 
  

   small 
  amount 
  of 
  apatite, 
  occurring 
  as 
  rounded 
  or 
  elongated 
  

   grains 
  between 
  the 
  augite 
  crystals, 
  with 
  ilmenite, 
  as 
  irregular 
  

   grains, 
  sometimes 
  in 
  the 
  augite, 
  sometimes 
  about 
  its 
  margins, 
  

   with 
  a 
  little 
  biotite, 
  and 
  with 
  a 
  little 
  original, 
  brown 
  horn- 
  

   blende. 
  In 
  places 
  a 
  little 
  alteration 
  of 
  the 
  augite 
  to 
  hornblende 
  

   was 
  noted, 
  and 
  occasionally 
  small 
  amounts 
  of 
  other 
  alteration 
  

   products 
  were 
  seen, 
  among 
  them 
  calcite. 
  On 
  the 
  whole 
  the 
  

   material 
  was 
  quite 
  fresh. 
  

  

  In 
  the 
  hand 
  specimen 
  the 
  augite 
  is 
  black 
  in 
  color 
  and 
  of 
  

   rather 
  irregular 
  habit, 
  although 
  there 
  is 
  a 
  well-marked 
  tendency 
  

   toward 
  the 
  prismatic 
  development. 
  The 
  grain 
  is 
  rather 
  fine, 
  

   the 
  length 
  of 
  the 
  prisms 
  rarely 
  exceeding 
  2 
  mm 
  . 
  The 
  cleavage, 
  

   while 
  distinct, 
  is 
  rather 
  poorly 
  developed. 
  There 
  is 
  perhaps 
  a 
  

   suggestion 
  of 
  a 
  schistose 
  texture 
  present. 
  

  

  In 
  thin-section, 
  the 
  grains 
  have, 
  in 
  general, 
  irregular 
  forms, 
  

   although 
  the 
  tendency 
  to 
  elongation 
  in 
  the 
  direction 
  of 
  the 
  

   vertical 
  axis 
  is 
  obvious. 
  The 
  cleavage 
  is 
  poorly 
  developed. 
  

   The 
  majority 
  of 
  the 
  grains 
  show 
  minute, 
  black, 
  rod-like 
  inclu- 
  

   sions 
  arranged 
  in 
  two 
  distinct 
  series. 
  In 
  many 
  of 
  the 
  grains 
  

   the 
  inclusions 
  are 
  very 
  abundant, 
  and 
  are 
  a 
  striking 
  character- 
  

   istic 
  ; 
  in 
  other 
  grains 
  they 
  are 
  less 
  numerous, 
  or 
  almost 
  absent. 
  

  

  * 
  Geology 
  of 
  the 
  Ice 
  River 
  District, 
  B. 
  C, 
  Thesis 
  for 
  the 
  Degree 
  of 
  Doctor 
  

   of 
  Philosophy, 
  Massachusetts 
  Institute 
  of 
  Technology, 
  1912. 
  

  

  f 
  Attempts 
  were 
  made 
  to 
  isolate 
  this 
  green 
  pyroxene 
  for 
  chemical 
  analysis, 
  

   but 
  without 
  entirely 
  satisfactory 
  results 
  with 
  the 
  material 
  at 
  the 
  time 
  avail- 
  

   able. 
  

  

  