﻿696 
  Forty- 
  seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  Certainly 
  these 
  are 
  the 
  forms 
  of 
  ore 
  produced 
  by 
  metamorphism, 
  

   and 
  in 
  the 
  present 
  instance 
  the 
  metamorphism 
  has 
  surely 
  been 
  

   sufficient 
  to 
  have 
  effected 
  this 
  result 
  

  

  But 
  the 
  strongest 
  argument 
  against 
  the 
  theory 
  of 
  original 
  

   deposition 
  lies 
  in 
  what 
  it 
  fails 
  to 
  explain 
  — 
  the 
  common 
  presence 
  

   of 
  granite 
  intrusions 
  in 
  the 
  ore, 
  and 
  the 
  amount 
  and 
  peculiar 
  

   character 
  of 
  the 
  chemical 
  action 
  that 
  is 
  shown 
  in 
  connection 
  with 
  

   the 
  deposits 
  and 
  nowhere 
  else 
  in 
  the 
  region. 
  If 
  the 
  ore 
  is 
  an 
  

   original 
  sediment 
  no 
  reason 
  is 
  apparent 
  why 
  it 
  should 
  so 
  often 
  be 
  

   intruded 
  by 
  granite, 
  or 
  wiry 
  it 
  should 
  be 
  the 
  locus 
  of 
  unusual 
  

   chemical 
  activity. 
  

  

  That 
  there 
  have 
  been 
  such 
  intrusions 
  of 
  granite 
  and 
  marked 
  

   chemical 
  action 
  is 
  ascertained 
  by 
  examining 
  the 
  constant 
  associate 
  

   of 
  the 
  ore 
  which 
  is 
  usually 
  referred 
  to 
  as 
  serpentine 
  The 
  true 
  

   character 
  of 
  this 
  rock 
  has 
  never 
  been 
  known, 
  and 
  as 
  it 
  is 
  interest- 
  

   ing 
  in 
  itself 
  and 
  seems 
  to 
  have 
  some 
  genetic 
  connection 
  with 
  the 
  

   ore, 
  a 
  particular 
  effort 
  has 
  been 
  made 
  to 
  ascertain 
  its 
  origin. 
  

   Emmons* 
  considered 
  it 
  serpentine 
  and, 
  as 
  already 
  stated, 
  classed 
  

   it 
  as 
  an 
  igneous 
  rock 
  By 
  Shepard 
  j* 
  it 
  was 
  described 
  as 
  a 
  dis- 
  

   tinct 
  mineral, 
  Dysyntribite, 
  and 
  he 
  published 
  an 
  analysis 
  of 
  a 
  

   specimen 
  from 
  the 
  Caledonia 
  mines 
  which 
  showed 
  a 
  composition 
  

   entirely 
  different 
  from 
  that 
  of 
  serpentine. 
  Later 
  Smith 
  and 
  

   Brush 
  J 
  presented 
  facts 
  to 
  show 
  that 
  the 
  material 
  should 
  not 
  be 
  

   classed 
  as 
  a 
  mineral 
  species, 
  being 
  of 
  too 
  uncertain 
  composition. 
  

   These 
  investigations 
  do 
  not 
  seem 
  to 
  have 
  found 
  their 
  way 
  into 
  

   geological 
  literature, 
  and 
  later 
  writers 
  generally 
  refer 
  to 
  the 
  

   rock 
  as 
  serpentine, 
  though 
  often 
  implying 
  a 
  doubt 
  as 
  to 
  its 
  pre- 
  

   cise 
  nature. 
  

  

  The 
  best 
  exposures 
  are 
  in 
  the 
  open 
  pit 
  of 
  the 
  Old 
  Sterling 
  

   mine 
  where 
  it 
  forms 
  the 
  bottom 
  rock. 
  The 
  contact 
  between 
  the 
  

   ore 
  and 
  " 
  serpentine 
  " 
  is 
  most 
  irregular, 
  and 
  where 
  the 
  ore 
  has 
  

   been 
  removed 
  the 
  " 
  serpentine" 
  forms 
  projecting 
  knobs, 
  masses 
  and 
  

   walls. 
  In 
  mining, 
  the 
  same 
  rock 
  is 
  sometimes 
  encountered 
  

   cutting 
  off 
  the 
  ore, 
  but 
  by 
  continuing 
  through 
  it 
  the 
  ore 
  is 
  reached 
  

   again. 
  In 
  short, 
  the 
  contact 
  between 
  the 
  ore 
  and 
  "serpentine" 
  

   is 
  clearly 
  an 
  irruptive 
  one. 
  

  

  * 
  Loc. 
  cit. 
  

  

  tC. 
  U. 
  Shepard, 
  Am. 
  Jour. 
  Sci., 
  (2) 
  XII, 
  p. 
  209 
  ; 
  Treatise 
  on 
  Mineralogy, 
  p. 
  146. 
  

  

  X 
  J. 
  L. 
  Smith 
  and 
  Q. 
  W. 
  Brush, 
  Amer. 
  Jour. 
  Sci., 
  (2) 
  XVI, 
  p. 
  50. 
  

  

  