﻿34 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  THE 
  ORIGIN 
  OF 
  SERPENTINE. 
  

  

  The 
  origin 
  of 
  serpentine 
  rocks 
  was 
  for 
  a 
  very 
  long 
  time 
  a 
  matter 
  

   of 
  controversy 
  among 
  geologists. 
  They 
  have 
  been 
  variously 
  

   regarded 
  as 
  primary 
  deposits, 
  as 
  plutonic 
  rocks, 
  as 
  alteration 
  pro- 
  

   ducts 
  of 
  rocks 
  rich 
  in 
  anhydrous 
  magnesian 
  silicates 
  and 
  as 
  the 
  result 
  

   of 
  metasomatic 
  change 
  in 
  rocks 
  of 
  any 
  kind 
  whatsoever, 
  by 
  the 
  sub- 
  

   stitution 
  of 
  a 
  hydrous 
  magnesian 
  sihcate 
  for 
  some 
  other 
  silicate 
  or 
  

   carbonate. 
  

  

  About 
  the 
  middle 
  of 
  the 
  present 
  century 
  Bischof 
  and 
  Gustav 
  Rose 
  

   expressed 
  the 
  unqualified 
  opinion 
  that 
  all 
  serpentines 
  were 
  of 
  second- 
  

   ary 
  origin, 
  but 
  as 
  they 
  v/ere 
  chemists 
  rather 
  than 
  geologists 
  and 
  did 
  

   not 
  undertake 
  to 
  discuss 
  the 
  various 
  geognostic 
  problems 
  involved 
  in 
  

   the 
  study 
  of 
  these 
  rocks, 
  they 
  were 
  unable 
  to 
  account 
  for 
  all 
  the 
  

   phenomena 
  associated 
  with 
  them, 
  and 
  their 
  views, 
  with 
  which 
  those 
  

   of 
  many 
  other 
  chemists 
  and 
  mineralogists 
  coincided, 
  were 
  not 
  

   accepted 
  by 
  geologists 
  as 
  conclusive. 
  

  

  Since 
  most 
  of 
  the 
  minerals 
  from 
  which 
  serpentine 
  was 
  held 
  to 
  be 
  

   derived, 
  viz.: 
  Olivine, 
  enstatite, 
  hornblende, 
  augite, 
  diallage 
  and 
  

   chondrodite, 
  were 
  believed 
  to 
  belong 
  pre-eminently 
  to 
  eruptive 
  

   rocks, 
  it 
  was 
  considered 
  inevitable 
  that 
  if 
  the 
  serpentines 
  were 
  all 
  of 
  

   secondary 
  origin 
  they 
  must 
  have 
  been 
  derived 
  from 
  igneous 
  rocks, 
  

   and 
  as 
  this 
  hypothesis, 
  in 
  many 
  cases, 
  did 
  not 
  agree 
  with 
  the 
  appar- 
  

   ent 
  stratigraphic 
  conditions,. 
  it 
  did 
  not 
  gain 
  general 
  acceptance. 
  For 
  

   example, 
  many 
  serpentines 
  were 
  found 
  distinctly 
  stratified 
  and 
  inti- 
  

   mately 
  associated 
  with 
  stratified 
  crystalline 
  rocks, 
  some 
  of 
  which 
  

   were 
  limestones 
  and 
  obviously 
  not 
  of 
  igneous 
  origin. 
  Dr. 
  T. 
  Sterry 
  

   Hunt, 
  who 
  has 
  discussed 
  the 
  origin 
  of 
  serpentines 
  at 
  great 
  length,* 
  

   while 
  conceding 
  the 
  alteration 
  of 
  olivine 
  and 
  enstatite 
  into 
  serpentine 
  

   in 
  some 
  cases, 
  considers 
  the 
  association 
  of 
  serpentine 
  with 
  these 
  two 
  

   minerals 
  to 
  be 
  an 
  evidence 
  of 
  the 
  simultaneous 
  development 
  of 
  

   hydrous 
  and 
  anhydrous 
  silicates 
  from 
  a 
  magnesian 
  sediment 
  of 
  chem- 
  

   ical 
  origin 
  such 
  as 
  he 
  ascribes 
  to 
  all 
  crystalline 
  stratified 
  rocks. 
  He 
  

   also 
  expresses 
  doubt 
  as 
  to 
  the 
  igneous 
  origin 
  of 
  many 
  of 
  the 
  olivine 
  

   rocks 
  from 
  which 
  serpentine 
  is 
  held 
  by 
  others 
  to 
  be 
  derived. 
  

  

  • 
  Trans. 
  Royal 
  Soc. 
  Canada, 
  Vol. 
  I, 
  § 
  iv, 
  1883. 
  

  

  