﻿Report 
  of 
  the 
  State 
  Geologist. 
  707 
  

  

  magnesian 
  and 
  silicious 
  materials, 
  forming 
  tremolite. 
  Where 
  

   the 
  calcareous 
  material 
  was 
  in 
  considerable 
  quantity 
  there 
  was 
  

   formed 
  a 
  tremolite 
  limestone 
  ; 
  where 
  it 
  was 
  a 
  minor 
  constituent 
  

   there 
  was 
  formed 
  a 
  tremolite 
  schist. 
  Under 
  the 
  influence 
  of 
  

   subterranean 
  waters 
  chemical 
  changes 
  have 
  been 
  produced. 
  The 
  

   tremolite 
  has 
  taken 
  up 
  the 
  elements 
  of 
  water, 
  the 
  lime 
  has 
  passed 
  

   away 
  into 
  solution, 
  and 
  talc 
  has 
  resulted. 
  At 
  the 
  same 
  time 
  any 
  

   calcite 
  associated 
  with 
  the 
  tremolite 
  would 
  be 
  removed, 
  rendering 
  

   the 
  talc 
  bed 
  more 
  pure 
  While 
  tremolite 
  seems 
  to 
  have 
  been 
  the 
  

   predominant 
  source 
  of 
  talc 
  it 
  is 
  highly 
  probable 
  that 
  some 
  

   actinolite 
  and 
  varieties 
  of 
  pyroxene 
  have 
  entered 
  into 
  the 
  process, 
  

   as 
  they 
  might 
  well 
  be 
  present 
  and 
  would 
  be 
  similarly 
  affected. 
  

   The 
  essential 
  agent 
  for 
  such 
  chemical 
  changes 
  is 
  water 
  containing 
  

   carbon 
  dioxide 
  in 
  solution, 
  an 
  agent 
  so 
  widely 
  diffused 
  as 
  to 
  

   render 
  unnecessary 
  any 
  special 
  explanation 
  of 
  its 
  presence 
  in 
  this 
  

   instance. 
  The 
  operation 
  may 
  have 
  been 
  aided 
  by 
  the 
  presence 
  

   of 
  magnesia 
  in 
  the 
  solution, 
  but 
  of 
  this 
  there 
  is 
  no 
  positive 
  

   evidence. 
  

  

  This 
  process 
  of 
  talc 
  formation 
  is 
  so 
  familiar, 
  in 
  the 
  production 
  

   of 
  talc 
  pseudomorphs 
  after 
  amphibole 
  and 
  pyroxenes 
  and 
  in 
  the 
  

   formation 
  elsewhere 
  of 
  considerable 
  talc 
  deposits 
  that 
  it 
  is 
  

   unnecessary 
  to 
  refer 
  to 
  particular 
  instances. 
  Descriptions 
  of 
  such 
  

   occurrences 
  may 
  be 
  found 
  in 
  Dana's 
  System 
  of 
  Mineralogy, 
  in 
  

   Roth's 
  Allgemeine 
  and 
  Chemische 
  G-eologie 
  and 
  in 
  other 
  works 
  

   of 
  a 
  similar 
  nature. 
  That 
  the 
  process 
  is 
  one 
  of 
  common 
  occur- 
  

   rence 
  is 
  an 
  additional 
  argument 
  in 
  favor 
  of 
  the 
  views 
  advanced. 
  

  

  Though 
  the 
  talc 
  is 
  abundant 
  in 
  the 
  belt 
  now 
  worked, 
  the 
  belt 
  

   is 
  itself 
  rather 
  limited 
  — 
  only 
  eight 
  or 
  ten 
  miles 
  long 
  and 
  a 
  mile 
  

   or 
  less 
  wide. 
  It, 
  therefore, 
  becomes 
  important 
  to 
  determine 
  

   whether 
  or 
  not 
  it 
  is 
  to 
  be 
  found 
  outside 
  of 
  this 
  belt 
  The 
  pres- 
  

   ence 
  of 
  tremolite 
  layers 
  in 
  various 
  parts 
  of 
  the 
  limestone 
  area 
  

   suggests 
  that 
  talc 
  may 
  occur, 
  and 
  some 
  prospecting 
  has 
  been 
  

   done, 
  but 
  thus 
  far 
  without 
  success. 
  It 
  must 
  be 
  remembered 
  that 
  

   while 
  tremolite 
  may 
  change 
  to 
  talc, 
  it 
  will 
  do 
  so 
  only 
  when 
  the 
  

   conditions 
  are 
  right, 
  and, 
  therefore, 
  the 
  occurrence 
  of 
  tremolite 
  is 
  

   no 
  proof 
  of 
  the 
  presence 
  of 
  talc. 
  Moreover, 
  the 
  peculiar 
  

   character 
  possessed 
  by 
  the 
  limestone 
  of 
  the 
  talc 
  belt, 
  described 
  

   above, 
  is 
  repeated 
  nowhere 
  else 
  in 
  the 
  region 
  examined, 
  and, 
  as 
  

  

  