﻿36 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  anhydrous 
  silicates 
  of 
  magnesia 
  from 
  the 
  alteration 
  of 
  which 
  he 
  holds 
  

   all 
  serpentines 
  to 
  be 
  derived, 
  it 
  may 
  be 
  that 
  the 
  chromite 
  matrices 
  of 
  

   the 
  Snarum 
  pseudomorphs 
  were 
  deposited 
  about 
  them 
  after 
  their 
  

   formation 
  and 
  were 
  subjected 
  to 
  little 
  or 
  no 
  expansive 
  force, 
  since, 
  

   after 
  the 
  crystals 
  were 
  thus 
  enclosed 
  and 
  protected 
  from 
  external 
  

   agencies 
  tlie 
  process 
  of 
  serpentinization 
  would 
  cease. 
  

  

  Tschermak, 
  in 
  his 
  memoir 
  on 
  the 
  formation 
  of 
  serpentine,* 
  quotes 
  

   the 
  words 
  of 
  Gustav 
  Rose 
  and 
  Volger 
  in 
  their 
  description 
  of 
  the 
  

   Snarum 
  crystals. 
  Rose 
  writes 
  as 
  follows 
  : 
  

  

  " 
  Of 
  two 
  crystals 
  the 
  surface 
  is 
  dark 
  leek-green, 
  soft 
  and 
  a 
  perfect 
  

   serpentine. 
  On 
  the 
  freshly 
  broken 
  surface, 
  however, 
  the 
  fact 
  is 
  

   evident 
  that 
  the 
  serpentine 
  is 
  only 
  from 
  one-half 
  to 
  two 
  lines 
  (i-4mm.) 
  

   thick 
  and 
  graduates 
  into 
  a 
  very 
  light, 
  yellowish-green 
  mass 
  which 
  

   traverses 
  the 
  crystal 
  irregularly 
  and 
  encloses 
  white 
  areas 
  with 
  a 
  high 
  

   lustre, 
  which 
  are 
  so 
  hard 
  that 
  they 
  can 
  not 
  be 
  scratched 
  with 
  a 
  knife. 
  

   These 
  also 
  appear 
  to 
  have 
  cleavage 
  surfaces, 
  but 
  the 
  whole 
  mass 
  is 
  

   penetrated 
  with 
  fine 
  fissures, 
  and 
  the 
  small 
  individual 
  parts 
  are 
  bril- 
  

   liant 
  on 
  almost 
  every 
  side 
  so 
  that 
  the 
  true 
  cleavage 
  cracks 
  can 
  not 
  be 
  

   determined. 
  ^ 
  , 
  

  

  '* 
  Through 
  another 
  crystal 
  passes 
  a 
  cleft 
  about 
  as 
  thick 
  as 
  a 
  sheet 
  

   of 
  paper, 
  which 
  is 
  filled 
  with 
  very 
  finely 
  fibrous, 
  highly 
  transparent, 
  

   leek-green 
  chrysotile. 
  From 
  this 
  spread 
  out 
  to 
  right 
  and 
  left, 
  fis- 
  

   sures 
  filled 
  in 
  a 
  similar 
  manner, 
  which 
  are 
  nearly 
  perpendicular 
  to 
  the 
  

   principal 
  crevice 
  and 
  which 
  turn 
  back 
  upon 
  themselves 
  in 
  ramifica- 
  

   tions 
  which 
  are 
  sometimes 
  very 
  small 
  and 
  sometimes 
  from 
  one 
  to 
  

   one 
  and 
  one-half 
  lines 
  (2-3mm.) 
  in 
  thickness. 
  

  

  " 
  Where 
  the 
  margins 
  of 
  these 
  turn 
  back 
  quickly 
  they 
  often 
  touch 
  

   and 
  intersect 
  themselves 
  and 
  the 
  whole 
  mass 
  between 
  them, 
  even 
  

   when 
  hard 
  and 
  brilliant, 
  is 
  colored 
  green; 
  where 
  they 
  meet 
  each 
  

   other 
  at 
  greater 
  distances 
  the 
  included 
  mass 
  is 
  white, 
  of 
  greater 
  

   toughness 
  than 
  in 
  the 
  first 
  crystal 
  and 
  of 
  subconchoidal 
  fracture. 
  

  

  " 
  It 
  is 
  here 
  evident 
  that 
  the 
  whole 
  mass 
  of 
  the 
  crystal 
  was 
  pene- 
  

   trated 
  by 
  fissures 
  which 
  became 
  filled 
  with 
  serpentine 
  and 
  from 
  which 
  

   the 
  decomposition 
  has 
  proceeded 
  in 
  all 
  directions." 
  

  

  *Sitz. 
  Wien. 
  Akad. 
  LVI., 
  ist 
  Abtheil. 
  

  

  