﻿JOURNAL 
  

  

  OF 
  THE 
  

  

  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  

  

  Vol. 
  12 
  May 
  19, 
  1922 
  No. 
  10 
  

  

  MINERALOGY. 
  — 
  Notes 
  op. 
  white 
  chlorites^ 
  Earl 
  V. 
  Shannon 
  and 
  

   Edgar 
  T. 
  Wherry, 
  U. 
  S. 
  National 
  Museum. 
  

  

  Although 
  the 
  name 
  chlorite 
  comes 
  from 
  the 
  Greek 
  word 
  for 
  green, 
  

   various 
  other 
  colors 
  are 
  represented 
  among 
  this 
  group 
  of 
  minerals, 
  in- 
  

   cluding 
  violet-red 
  in 
  kaemmererite, 
  and 
  white 
  in 
  leuchtenbergite 
  and 
  

   other 
  sub-species 
  or 
  varieties. 
  The 
  mineral 
  colerainite, 
  described 
  in 
  

   1918 
  by 
  Poitevin 
  and 
  Graham,- 
  is 
  in 
  our 
  opinion 
  a 
  white 
  chlorite, 
  

   since 
  its 
  composition, 
  crystal 
  form, 
  optical 
  properties, 
  and 
  physical 
  

   properties 
  are 
  all 
  similar 
  in 
  many 
  respects 
  to 
  those 
  of 
  typical 
  members 
  

   of 
  the 
  clinochlore 
  group. 
  It 
  seemed 
  of 
  interest 
  to 
  ascertain 
  whether 
  

   the 
  material 
  reported 
  as 
  colerainite 
  from 
  Brinton's 
  Quarry, 
  Chester 
  

   County, 
  Pennsylvania, 
  by 
  Mr. 
  Samuel 
  G. 
  Gordon'^ 
  could 
  also 
  be 
  so 
  

   classified, 
  and 
  Mr. 
  Gordon 
  kindly 
  sent 
  the 
  Museum 
  samples 
  for 
  exami- 
  

   nation 
  and 
  analysis. 
  Sample 
  1 
  is 
  composed 
  of 
  3 
  to 
  5 
  mm. 
  barrel 
  

   shaped 
  crystals, 
  bounded 
  by 
  greatl}^ 
  rounded 
  first 
  and 
  second 
  order 
  

   pyramids 
  and 
  prisms, 
  with 
  large 
  basal 
  planes. 
  These 
  are 
  not 
  solid, 
  

   but 
  have 
  a 
  dull 
  white 
  crust 
  with 
  loosely 
  packed 
  flaky 
  material 
  with 
  

   pearly 
  luster 
  within. 
  Under 
  the 
  microscope 
  the 
  material 
  is 
  fairly 
  

   homogeneous, 
  although 
  some 
  dull, 
  opaque 
  patches 
  are 
  present 
  min- 
  

   gled 
  with 
  the 
  transparent 
  flakes. 
  Specimen 
  2 
  is 
  from 
  a 
  new 
  locality 
  

   discovered 
  by 
  Mr. 
  Gordon, 
  namely 
  a 
  small 
  abandoned 
  feldspar 
  quarry 
  

   about 
  2 
  miles 
  southwest 
  of 
  Nottingham, 
  Chester 
  County, 
  Pa. 
  This 
  

   is 
  in 
  more 
  micaceous-looking 
  and 
  apparently 
  less 
  altered 
  crystals 
  of 
  

   similar 
  shape 
  and 
  size. 
  Under 
  the 
  microscope 
  its 
  homogeneity 
  is 
  satis- 
  

   factory. 
  Similar 
  material 
  occurs 
  also 
  in 
  feldspar 
  quarries 
  near 
  S3dmar, 
  

   Pa., 
  but 
  it 
  is 
  too 
  altered 
  for 
  analysis; 
  its 
  crystallography 
  is 
  described 
  

   below. 
  

  

  ' 
  Presented 
  at 
  the 
  meeting 
  of 
  the 
  Mineralogical 
  Society 
  of 
  America, 
  Dec. 
  29, 
  1921. 
  

   Published 
  by 
  permission 
  of 
  the 
  Secretary 
  of 
  the 
  Smithsonian 
  Institution. 
  Received 
  

   December 
  31, 
  1921. 
  

  

  2 
  Canada 
  Dept. 
  Mines, 
  Museum 
  Bull. 
  27: 
  66-73. 
  1918. 
  

  

  3Amer. 
  Min. 
  5: 
  195. 
  1920. 
  

  

  239 
  

  

  