﻿254 
  MISS 
  C. 
  A. 
  RAISIN 
  ON 
  THE 
  NATURE 
  AND 
  [May 
  1 
  897, 
  

  

  forms 
  of 
  the 
  serpentine, 
  differing 
  in 
  several 
  characteristics. 
  Whether 
  

   the 
  fibrous 
  part 
  is 
  connected 
  always 
  with 
  one 
  or 
  the 
  other 
  form 
  is 
  

   difficult 
  to 
  decide, 
  but 
  it 
  seems 
  certainly 
  in 
  some 
  cases 
  related 
  to 
  the 
  

   more 
  irregular 
  part, 
  since 
  it 
  can 
  be 
  traced 
  originating 
  either 
  as 
  

   patches 
  or 
  as 
  a 
  fringe 
  beginning 
  to 
  extend 
  into 
  the 
  kernels. 
  A 
  

   fourth 
  form 
  of 
  serpentine 
  with 
  close 
  parallel 
  structure 
  has 
  been 
  

   noticed 
  as 
  the 
  result 
  of 
  change 
  in 
  enstatite. 
  1 
  

  

  Although 
  these 
  observations 
  thus 
  agree 
  with 
  many 
  of 
  the 
  details 
  

   given 
  by 
  Herr 
  Weigand, 
  yet 
  some 
  additions 
  to 
  his 
  list 
  are 
  required, 
  

   and 
  the 
  presence 
  of 
  enstatite 
  especially 
  has 
  an 
  important 
  bearing, 
  

   as 
  it 
  is 
  distinctly 
  a 
  mineral 
  associated 
  with 
  peridotites 
  or 
  allied 
  

   rocks. 
  2 
  

  

  III. 
  Controversial 
  Questions. 
  

  

  The 
  characters 
  must 
  now 
  be 
  considered 
  in 
  which, 
  according 
  to 
  

   Weigand, 
  the 
  Rauenthal 
  serpentine 
  is 
  unlike 
  the 
  other 
  masses, 
  and 
  

   by 
  reason 
  of 
  which, 
  according 
  to 
  the 
  same 
  authority, 
  a 
  different 
  

   origin 
  must 
  be 
  attributed 
  to 
  it. 
  

  

  (1) 
  Accessory 
  Minerals. 
  

  

  It 
  is 
  stated 
  that 
  ' 
  the 
  accessory 
  minerals 
  so 
  characteristic 
  of 
  

   olivine-serpentine 
  here 
  are 
  wholly 
  wanting.' 
  3 
  It 
  is 
  true 
  that 
  

   picotite 
  does 
  not 
  appear 
  to 
  be 
  present, 
  but 
  it 
  is 
  absent 
  from 
  other 
  

   serpentines, 
  and 
  other 
  accessories 
  characteristic 
  of 
  peridotites 
  (perof- 
  

   skite, 
  rutile, 
  enstatite) 
  are 
  found 
  here. 
  

  

  (2) 
  Iron 
  Oxide. 
  

  

  A 
  second 
  important 
  distinction 
  is 
  stated 
  to 
  be 
  that, 
  ' 
  for 
  one 
  thing, 
  

   strings 
  of 
  iron 
  are 
  entirely 
  wanting, 
  and 
  in 
  consequence 
  differently 
  

   coloured 
  zones.' 
  3 
  The 
  serpentine 
  in 
  many 
  parts 
  has 
  a 
  rather 
  uniform 
  

   greenish 
  tint, 
  contains 
  only 
  minute 
  specks 
  of 
  ferrite 
  scattered 
  within 
  

   the 
  kernels, 
  or 
  aggregated 
  in 
  minutely 
  granular 
  strings 
  along 
  the 
  

  

  1 
  A 
  kind 
  of 
  spherulitic 
  serpentine 
  also 
  occurs 
  within 
  certain 
  veins 
  which 
  

   cross 
  the 
  amphibolite. 
  In 
  one 
  of 
  these, 
  a 
  very 
  pale 
  greenish 
  or 
  yellowish 
  

   isotropic 
  ground 
  exhibits, 
  with 
  polarized 
  light, 
  scattered 
  stars 
  which 
  consist 
  of 
  

   fibres, 
  evidently 
  serpentine 
  or 
  chrysotile. 
  A 
  vein 
  in 
  another 
  slide 
  shows, 
  in 
  

   polarized 
  light, 
  a 
  diaper-like 
  pattern 
  with 
  black 
  crosses 
  similar 
  to 
  that 
  of 
  

   spherulitic 
  rhyolites. 
  At 
  other 
  parts 
  wedge-shaped 
  crystallites 
  grow 
  in 
  tufts 
  

   from 
  the 
  sides 
  of 
  the 
  rein. 
  I 
  noticed 
  a 
  slight 
  development 
  of 
  a 
  similar 
  structure 
  

   in 
  a 
  serpentine 
  from 
  the 
  Lizard. 
  

  

  2 
  The 
  views 
  of 
  Herr 
  Weigand 
  as 
  to 
  the 
  Rauenthal 
  serpentine 
  are 
  quoted 
  by 
  

   Mr. 
  Teall 
  ('Brit. 
  Petrogr.' 
  1888, 
  pp. 
  110-112). 
  We 
  find 
  it 
  stated, 
  however, 
  in 
  

   another 
  place, 
  in 
  connexion 
  with 
  Sandberger's 
  results, 
  that 
  ' 
  one 
  or 
  more 
  of 
  

   the 
  minerals, 
  chromite, 
  picotite, 
  pleonaste, 
  chrome-diopside, 
  enstatite, 
  and 
  

   pyrope, 
  are 
  found 
  in 
  the 
  typical 
  peridotites. 
  The 
  occurrence 
  of 
  any 
  of 
  these 
  

   minerals 
  in 
  a 
  serpentine 
  is 
  therefore 
  strong 
  evidence 
  that 
  it 
  has 
  been 
  produced 
  

   by 
  the 
  alteration 
  of 
  an 
  olivine-rock.' 
  {Op. 
  cit. 
  p. 
  108.) 
  

  

  3 
  B. 
  Weigand, 
  op. 
  cit. 
  p. 
  201 
  : 
  — 
  'Ferner 
  fehlen 
  hier 
  im 
  Hornblendeserpentin 
  

   ganzlich 
  die 
  fur 
  den 
  Olivinserpentin 
  so 
  charakteristischen 
  accessorischen 
  Minera- 
  

  

  lien 
  Einmal 
  fehlen 
  hier 
  ganzlich 
  Erzschnure 
  und 
  damit 
  verschieden 
  

  

  gefarbte 
  Zonen.' 
  

  

  