﻿F. 
  W. 
  ClarTee 
  — 
  Gonsiituiion 
  of 
  Tourmaline. 
  115 
  

  

  10. 
  Al,(SiOJ.(BOJ, 
  . 
  B0,(A10H) 
  . 
  Mg.H.. 
  

   20. 
  Al,(SiO,).(BO,), 
  . 
  BO,Ca 
  . 
  Mg.H,. 
  

   3. 
  Al,(SiOJ 
  .(BO 
  J. 
  . 
  BO.Na, 
  . 
  Al.Na,. 
  

  

  For 
  comparison 
  the 
  analyses 
  by 
  Penfield 
  and 
  Foote 
  and 
  by 
  

   Riggs 
  are 
  available. 
  In 
  this 
  case 
  the 
  minute 
  quantities 
  of 
  

   titanium 
  are 
  ignored. 
  

  

  Found. 
  Eeduced. 
  

  

  P. 
  & 
  F. 
  Riggs. 
  P. 
  & 
  F. 
  Riggs. 
  Mean. 
  Calculated. 
  

  

  SiO, 
  36-72 
  36-88 
  36-56 
  36-81 
  36-69 
  36-'79 
  

  

  TiO, 
  -05 
  -12 
  __ 
  

  

  B^Og 
  10-81 
  10-58 
  10-76 
  10-56 
  10*66 
  10-74 
  

  

  Al.Og 
  29-68 
  28-87 
  29-55 
  28*81 
  29-18 
  29*07 
  

  

  FeO 
  -22 
  -52 
  ) 
  

  

  MgO. 
  14-92 
  14-53 
  ( 
  14*97 
  14*79 
  14*88 
  14*86 
  

  

  CaO 
  3-49 
  3-70 
  3-47 
  3*69 
  3-58 
  3-48 
  

  

  Ka,0 
  1-26 
  1-39) 
  1-28 
  1*50 
  1-39 
  1*44 
  

  

  K,0 
  -05 
  -18 
  j 
  

  

  H^O 
  2-98 
  3*56) 
  3-41 
  3-84 
  3-62 
  3-62 
  

  

  F 
  -93 
  -50 
  j 
  

  

  101.11 
  100-83 
  100-00 
  100*00 
  100*00 
  lOO'OO 
  

  

  The 
  dark 
  brown 
  tourmalines 
  from 
  Orford, 
  E". 
  H., 
  and 
  

   Monroe, 
  Conn., 
  as 
  analyzed 
  by 
  Kiggs, 
  also 
  reduce 
  to 
  similar 
  

   form, 
  and 
  approximate 
  to 
  the 
  mixture 
  

  

  15. 
  Al,(SiO 
  J^CBOJ, 
  . 
  B03(A10H) 
  . 
  Mg,H,, 
  

   6. 
  Al,(SiOJ,(BOJ,.BO,Ca.Mg,H,, 
  

   8. 
  A]^(SiOJ,(BOj, 
  . 
  B03NaH 
  . 
  Al3Na,H, 
  

  

  with 
  the 
  comparison 
  as 
  follows 
  : 
  

  

  Found. 
  Reduced. 
  

  

  Orford. 
  Monroe. 
  . 
  Orford. 
  Monroe. 
  Calculated. 
  

  

  SiO, 
  36-66 
  36-41 
  36*96 
  37*34 
  36*84 
  

  

  B^Og 
  10*07 
  9-65 
  10-16 
  9-89 
  10-74 
  

  

  Al.Og 
  32*84 
  31*27) 
  33'28 
  33*13 
  33*11 
  

  

  TiO, 
  -23 
  1-61 
  j 
  

  

  FeO 
  2*50 
  3*80 
  \ 
  

  

  MgO 
  10*35 
  9*47 
  j 
  11-84 
  11*88 
  11*85 
  

  

  CaO_ 
  1*35 
  -98 
  1*36 
  1*00 
  1*19 
  

  

  Na^O 
  2-42 
  2-68) 
  2*58 
  2-88 
  2-62 
  

  

  K,0 
  -22 
  -21 
  f 
  

  

  H^O 
  3*78 
  3*79 
  3*82 
  3*88 
  3*65 
  

  

  100-42 
  99-87 
  100-00 
  100*00 
  10000 
  

  

  