﻿Vol. 
  53.] 
  OKIGIN 
  OP 
  THE 
  KATJENTHAL 
  SEEPENTINE. 
  265 
  

  

  A 
  : 
  The 
  Kauenthal 
  serpentine 
  ; 
  the 
  bulk 
  analysis 
  given 
  by 
  Herr 
  Weigand. 
  1 
  

  

  B 
  : 
  The 
  matrix 
  of 
  the 
  dark 
  serpentine 
  from 
  near 
  Cadgwith. 
  2 
  

  

  C 
  : 
  Dark 
  oil-green 
  serpentine 
  from 
  Porthalla. 
  3 
  

  

  D 
  : 
  A 
  mica-peridotite 
  from 
  Kentucky, 
  described 
  by 
  J. 
  S. 
  Diller. 
  4 
  In 
  this 
  the 
  

   high 
  percentage 
  of 
  lime 
  and 
  alumina, 
  and 
  the 
  low 
  proportion 
  of 
  magnesia, 
  

   can 
  be 
  accounted 
  for 
  by 
  the 
  large 
  quantity 
  of 
  mica 
  present. 
  

  

  A. 
  B. 
  0. 
  D. 
  

  

  Si0 
  2 
  36944 
  38-50 
  37*15 
  3384 
  

  

  Ti0 
  o 
  378 
  

  

  A1 
  2 
  3 
  1-353 
  1-02 
  5-60 
  5-88 
  

  

  Cr.dg 
  0-18 
  

  

  Fe~0 
  3 
  6-868 
  466 
  MO 
  704 
  

  

  FeO 
  9563 
  331 
  880 
  5'16 
  

  

  MnO 
  016 
  

  

  NiO 
  0-59 
  010 
  

  

  CoO 
  trace 
  

  

  CaO 
  1-393 
  197 
  010 
  946 
  

  

  BaO 
  006 
  

  

  MsO 
  36022 
  36-40 
  3280 
  2296 
  

  

  K 
  2 
  '0 
  I 
  . 
  29 
  204 
  

  

  Na 
  2 
  f 
  u 
  " 
  y 
  0-33 
  

  

  H 
  2 
  13-089 
  12-35 
  j 
  1 
  q.^ 
  7*50 
  

  

  P 
  2 
  3 
  0-89 
  

  

  CI 
  005 
  

  

  F 
  ? 
  

  

  C0 
  2 
  0-43 
  

  

  FeS 
  0-41 
  

  

  Insol. 
  inHCl 
  137 
  

  

  Total 
  100-58 
  10000 
  9986 
  

  

  Specific 
  gravities 
  2-587 
  2'56 
  

  

  The 
  significance 
  of 
  the 
  occurrence 
  of 
  bastite 
  as 
  a 
  point 
  of 
  likeness 
  

   is 
  so 
  obvious 
  that 
  it 
  need 
  only 
  be 
  mentioned. 
  

  

  The 
  variation 
  in 
  many 
  masses 
  is 
  an 
  important 
  means 
  of 
  correlation, 
  

   since 
  it 
  is 
  from 
  this 
  character, 
  or 
  rather 
  from 
  the 
  overlooking 
  of 
  it, 
  

   that 
  some 
  difficulties 
  in 
  interpretation 
  have 
  arisen. 
  5 
  

  

  The 
  structural 
  characteristics 
  afford 
  a 
  means 
  of 
  comparison 
  with 
  

   other 
  serpentines. 
  For 
  instance, 
  in 
  the 
  Lizard 
  rocks, 
  the 
  occurrence 
  

   of 
  a 
  structure 
  both 
  on 
  the 
  eastern 
  and 
  the 
  western 
  coast, 
  which 
  

   resembles 
  a 
  slight 
  foliation, 
  has 
  been 
  noticed, 
  and 
  occasionally 
  there 
  

   is 
  also 
  banding, 
  especially 
  at 
  Porthalla. 
  6 
  

  

  1 
  Op. 
  tit. 
  p. 
  199. 
  

  

  2 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xlvii. 
  (1891) 
  p. 
  466. 
  Analysis 
  v., 
  by 
  

   Mr. 
  Hudleston. 
  

  

  8 
  Ibid., 
  analysis 
  vn., 
  by 
  Mr. 
  Collins. 
  

  

  4 
  Am. 
  Journ. 
  Sci. 
  ser. 
  3, 
  vol. 
  xliv. 
  (1892) 
  p. 
  288. 
  

  

  5 
  The 
  variability 
  of 
  Lizard 
  serpentines 
  is 
  well 
  shown 
  by 
  the 
  tabular 
  

   summary, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xlvii. 
  (1891) 
  p. 
  467. 
  

  

  6 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xlvii. 
  (1891) 
  pp. 
  470. 
  472, 
  474. 
  See 
  also 
  note 
  

   on 
  lherzolite 
  written 
  in 
  1876, 
  quoted 
  on 
  p. 
  475. 
  A 
  banded 
  specimen 
  which 
  I 
  

   brought 
  from 
  Bonhomme 
  is 
  practically 
  identical 
  with 
  that 
  from 
  Porthalla 
  which 
  

   is 
  represented 
  in 
  pi. 
  xvi. 
  

  

  A 
  similar 
  structure 
  (fluxional 
  or 
  banded) 
  has 
  been 
  observed 
  in 
  other 
  non- 
  

   crystalline 
  igneous 
  rocks, 
  as 
  in 
  the 
  diorites 
  of 
  Guernsey 
  (Quart. 
  Journ. 
  Geol. 
  Soc. 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  210. 
  t 
  

  

  