﻿246 
  MISS 
  C. 
  A. 
  RAISIN 
  ON 
  THE 
  NATURE 
  AND 
  [May 
  1897, 
  

  

  20. 
  On 
  the 
  Nature 
  and 
  Origin 
  of 
  the 
  Eauenthal 
  Serpentine. 
  

   By 
  Miss 
  Catherine 
  A. 
  Eaisin, 
  B.Sc 
  (Communicated 
  by 
  

   Prof. 
  T. 
  G. 
  Bonney, 
  D.Sc, 
  LL.D., 
  F.B.S., 
  V.P.G.S. 
  Bead 
  

   February 
  24th, 
  1897.) 
  

  

  [Plates 
  XVI. 
  & 
  XVII.] 
  

  

  Contents. 
  

  

  Page 
  

  

  Introduction 
  246 
  

  

  I. 
  Investigation 
  in 
  the 
  Field 
  247 
  

  

  II. 
  Microscopic 
  Details 
  251 
  

  

  III. 
  Controversial 
  Questions 
  254 
  

  

  IV. 
  Comparison 
  with 
  other 
  Serpentines 
  from 
  the 
  Vosges 
  261 
  

  

  V. 
  Comparison 
  with 
  Serpentines 
  from 
  other 
  Localities 
  263 
  

  

  VI. 
  Summary 
  266 
  

  

  Introduction. 
  

  

  The 
  general 
  origin 
  of 
  the 
  rock 
  serpentine 
  as 
  a 
  metamorphosed 
  

   peridotite 
  is 
  now 
  usually 
  admitted 
  since 
  the 
  investigations, 
  which 
  

   have 
  become 
  classic, 
  of 
  Profs. 
  Tschermak, 
  Sandberger, 
  Bonney, 
  

   and 
  other 
  later 
  observers. 
  An 
  exception 
  is 
  made, 
  however, 
  for 
  

   certain 
  masses 
  by 
  some 
  geologists. 
  One 
  of 
  the 
  most 
  interesting 
  

   of 
  these 
  is 
  that 
  described 
  as 
  the 
  Eauenthal 
  serpentine. 
  The 
  

   hypothesis 
  which 
  was 
  put 
  forward 
  by 
  Weigand 
  in 
  1875 
  x 
  was 
  that 
  

   this 
  did 
  not 
  originate 
  from 
  a 
  peridotite, 
  that 
  it 
  is 
  indeed 
  a 
  meta- 
  

   morphosed 
  rock, 
  but 
  is 
  the 
  result 
  of 
  the 
  metamorphosis 
  of 
  part 
  of 
  

   a 
  gneiss. 
  The 
  investigation 
  of 
  the 
  genesis 
  of 
  this 
  rock 
  thus 
  has 
  a 
  

   bearing 
  on 
  an 
  important 
  general 
  petrological 
  question. 
  Exception 
  

   was 
  taken 
  to 
  the 
  conclusions 
  of 
  Herr 
  Weigand 
  by 
  Prof. 
  Bonney 
  from 
  

   the 
  study 
  of 
  microscopic 
  slices. 
  2 
  In 
  consequence 
  of 
  this, 
  on 
  my 
  

   return 
  journey 
  from 
  Switzerland 
  in 
  1895, 
  I 
  turned 
  aside 
  to 
  visit 
  

   the 
  Eauenthal, 
  and 
  brought 
  back 
  a 
  few 
  specimens, 
  with 
  the 
  idea 
  

   that 
  they 
  might 
  be 
  useful 
  in 
  the 
  further 
  examination 
  of 
  the 
  question 
  

   which 
  I 
  hoped 
  that 
  Prof. 
  Bonney 
  intended 
  to 
  make. 
  As, 
  how- 
  

   ever, 
  it 
  was 
  not 
  possible 
  for 
  him 
  to 
  visit 
  the 
  locality 
  himself 
  for 
  

   some 
  time, 
  he 
  asked 
  me 
  to 
  continue 
  the 
  investigation, 
  which 
  I 
  did 
  

   in 
  the 
  summer 
  of 
  1896, 
  spending 
  about 
  a 
  fortnight 
  in 
  the 
  district. 
  

   From 
  the 
  numerous 
  specimens 
  then 
  collected, 
  many 
  slides 
  have 
  

   been 
  prepared, 
  the 
  inferences 
  from 
  which 
  seem 
  entirely 
  to 
  corrobo- 
  

   rate 
  the 
  views 
  formed 
  on 
  the 
  spot. 
  I 
  have 
  been 
  able 
  fortunately 
  to 
  

   submit 
  to 
  Prof. 
  Bonrjey 
  the 
  specimens 
  and 
  slides, 
  and 
  he 
  kindly 
  

   allows 
  me 
  to 
  state 
  that 
  he 
  agrees 
  with 
  the 
  main 
  conclusions 
  from 
  

   them 
  as 
  here 
  put 
  forward. 
  For 
  all 
  the 
  help 
  of 
  various 
  kinds 
  given 
  

   to 
  me 
  by 
  him 
  in 
  this 
  investigation, 
  and 
  for 
  the 
  facilities 
  most 
  

   generously 
  afforded 
  for 
  examining 
  his 
  numerous 
  specimens 
  of 
  

   serpentines 
  from 
  other 
  localities, 
  I 
  would 
  here 
  offer 
  my 
  best 
  thanks. 
  

  

  1 
  Jahrb. 
  d. 
  k.-k. 
  Geol. 
  Keichsanstalt, 
  vol. 
  xxv. 
  (1875) 
  p. 
  183 
  : 
  or 
  Tschermak, 
  

   Min. 
  & 
  Petr. 
  Mitth. 
  1875. 
  2 
  Geol. 
  Mag. 
  1887, 
  p. 
  65. 
  

  

  