﻿certain 
  Micas, 
  Vermiculites 
  and 
  Chlorites. 
  249 
  

  

  From 
  the 
  remaining 
  ratios, 
  writing 
  MgOH 
  as 
  P', 
  the 
  sub- 
  

   joined 
  empirical 
  formulae 
  are 
  directly 
  derived 
  : 
  

  

  Newlin 
  R'" 
  401 
  R", 
  M 
  R',„ 
  H 
  1!C4 
  (SiO,) 
  5 
  ,„ 
  O„ 
  , 
  

  

  " 
  Painterite 
  " 
  B. 
  R'" 
  !76 
  R" 
  883 
  R',„ 
  H 
  15 
  „ 
  (SiOJ 
  581 
  O, 
  ,. 
  

  

  C. 
  R" 
  sco 
  R'' 
  SS1 
  R' 
  !S9 
  H 
  m9 
  (SiO 
  ( 
  ) 
  566 
  0„, 
  

  

  Reduced 
  to 
  structural 
  form 
  these 
  give 
  less 
  satisfactory 
  

   results 
  than 
  the 
  previously 
  considered 
  vermiculites. 
  The 
  

   Newlin 
  mineral 
  may 
  be 
  regarded 
  as 
  nearly 
  a 
  hydroclintonite, 
  

   A10 
  2 
  MgSi0 
  4 
  H 
  3 
  with 
  an 
  admixture 
  of 
  an 
  amesite-like 
  com- 
  

   pound 
  Mg 
  2 
  OSi0 
  4 
  (MgOH) 
  2 
  in 
  the 
  ratio 
  4:1. 
  In 
  reality 
  the 
  

   mixture 
  is 
  more 
  complicated, 
  and 
  must 
  contain 
  other 
  mole- 
  

   cules. 
  The 
  "painterite" 
  C, 
  is 
  wholly 
  chloritic, 
  containing 
  the 
  

   amesite 
  molecule 
  Mg 
  2 
  OSi0 
  4 
  (AlH 
  2 
  2 
  ) 
  2 
  , 
  with 
  the 
  molecules 
  

   Mg(Si0 
  4 
  ) 
  2 
  (MgOH) 
  6 
  and 
  Mg(Si0 
  4 
  ) 
  2 
  H 
  6 
  , 
  in 
  the 
  ratio 
  16:4:18. 
  

   These 
  compare 
  with 
  the 
  actual 
  analyses, 
  reduced 
  to 
  typical 
  

   form 
  and 
  100 
  per 
  cent, 
  thus 
  : 
  

  

  

  Newlin. 
  

  

  "Painterite." 
  

  

  

  Found. 
  

  

  Calc. 
  

  

  Found. 
  

  

  Calc. 
  

  

  Si0 
  2 
  

  

  32'42 
  

  

  31-57 
  

  

  35-03 
  

  

  35-59 
  

  

  A1 
  2 
  3 
  

  

  21*39 
  

  

  2T47 
  

  

  16-22 
  

  

  16-13 
  

  

  MgO 
  

  

  33-57 
  

  

  33-69 
  

  

  31-77 
  * 
  

  

  30-84 
  

  

  H 
  2 
  

  

  12-62 
  

  

  13-27 
  

  

  16-98 
  

  

  17-44 
  

  

  

  100-00 
  

  

  100-00 
  

  

  100-00 
  

  

  100-00 
  

  

  ) 
  in 
  MgOH 
  . 
  

  

  . 
  6-09 
  

  

  8-42 
  

  

  8-56 
  

  

  9-49 
  

  

  The 
  " 
  Painterite 
  " 
  B 
  reduces 
  less 
  easily, 
  but 
  satisfies 
  all 
  the 
  

   required 
  conditions. 
  It 
  is 
  like 
  C, 
  but 
  contains 
  other 
  chloritic 
  

   molecules 
  in 
  somewhat 
  complex 
  ratios. 
  It 
  must 
  be 
  remembered 
  

   that 
  all 
  these 
  minerals 
  are 
  mixtures, 
  and 
  the 
  fact 
  that 
  they 
  are 
  

   reducible 
  at 
  all 
  to 
  simple 
  expressions 
  is 
  a 
  strong 
  point 
  in 
  favor 
  

   of 
  the 
  theory 
  adopted 
  for 
  the 
  chlorites 
  and 
  micas 
  in 
  general. 
  

  

  A 
  very 
  interesting 
  example 
  of 
  the 
  way 
  in 
  which 
  the 
  chloritic 
  

   vermiculites 
  approach 
  the 
  serpentines 
  in 
  composition 
  and 
  char- 
  

   acter 
  has 
  been 
  furnished 
  us 
  by 
  Mr. 
  Gr. 
  P. 
  Merrill 
  of 
  the 
  U. 
  S. 
  

   National 
  Museum. 
  It 
  was 
  found 
  by 
  him 
  at 
  Old 
  Wolf 
  Quarry, 
  

   Chestnut 
  Hill, 
  Easton, 
  Pa., 
  and 
  is 
  described 
  by 
  him 
  as 
  follows 
  : 
  

  

  " 
  It 
  occurs 
  in 
  the 
  form 
  of 
  bright 
  yellowish 
  green 
  inelastic 
  

   scales 
  of 
  all 
  sizes 
  up 
  to 
  an 
  inch 
  in 
  diameter, 
  associated 
  with 
  a 
  

   compact 
  tremolite 
  rock 
  which 
  is 
  here 
  quarried 
  and 
  pulverized 
  

   for 
  use 
  as 
  a 
  filler 
  in 
  paper 
  manufacture. 
  The 
  character 
  of 
  the 
  

   rock 
  is 
  greatly 
  varied, 
  but 
  at 
  the 
  quarry 
  opening 
  the 
  prevailing 
  

   material 
  is 
  tremolite 
  more 
  or 
  less 
  altered 
  into 
  serpentine, 
  the 
  

   vermiculite, 
  and 
  other 
  secondary 
  products, 
  including 
  calcite 
  in 
  

   both 
  fibrous 
  and 
  granular 
  forms. 
  

  

  The 
  vermiculite, 
  although 
  occurring 
  in 
  plates 
  of 
  considerable 
  

   thickness 
  readily 
  separable 
  into 
  thin 
  foliae, 
  never, 
  so 
  far 
  as 
  

   observed, 
  shows 
  good 
  crystal 
  outlines. 
  Optically 
  it 
  is 
  biaxial 
  

  

  