﻿J. 
  B. 
  Umpleby, 
  etc. 
  — 
  Custerite 
  : 
  A 
  New 
  Mineral. 
  389 
  

  

  treated 
  with 
  HC1 
  as 
  to 
  form 
  a 
  stiff 
  coherent 
  mass. 
  The 
  sepa- 
  

   rated 
  gelatinous 
  silica 
  floats 
  around 
  in 
  an 
  excess 
  of 
  acid, 
  the 
  

   solution 
  itself 
  not 
  gelatinizing 
  on 
  further 
  boiling. 
  Custerite, 
  

   therefore, 
  does 
  not 
  "gelatinize" 
  like 
  natrolite. 
  

  

  Composition. 
  — 
  The 
  chemical 
  analysis 
  showed 
  that 
  water, 
  

   fluorine, 
  silica, 
  and 
  lime 
  were 
  the 
  essential 
  constituents, 
  the 
  

   small 
  amounts 
  of 
  iron 
  and 
  magnesium 
  present 
  being 
  probably 
  

   due 
  to 
  magnetite 
  and 
  diopside, 
  respectively. 
  Fairly 
  pure, 
  

   fresh 
  material, 
  suitable 
  for 
  analysis, 
  was 
  only 
  available 
  in 
  por- 
  

   tions 
  of 
  from 
  one-fourth 
  to 
  three-fourth 
  grams. 
  

  

  The 
  analytical 
  results 
  obtained 
  (by 
  W. 
  T. 
  Schaller) 
  are 
  

   shown 
  in 
  the 
  following 
  table 
  : 
  

  

  Analyses 
  and 
  Ratios 
  of 
  Custerite. 
  

  

  1 
  2 
  Average 
  Eatios 
  

  

  Si0 
  2 
  32-13 
  32-20 
  32*17 
  '536 
  

  

  CaO 
  55-11 
  55-11 
  -984 
  

  

  H 
  2 
  __ 
  _ 
  5-53 
  5-06 
  5-30 
  '294 
  

  

  F 
  8-12 
  8*12 
  -427 
  

  

  MgO._ 
  1-19 
  1*19 
  1*19 
  -030 
  

  

  Magnetite 
  0'85 
  1*14 
  1*00 
  

  

  102-89 
  

   Excess 
  of 
  O 
  due 
  to 
  F 
  — 
  3-42 
  

  

  99-47 
  

  

  These 
  results 
  were 
  verified 
  by 
  a 
  partial 
  analysis 
  (water 
  not 
  

   being 
  determined) 
  of 
  a 
  different, 
  somewhat 
  less 
  pure, 
  portion 
  

   of 
  the 
  same 
  specimen 
  of 
  custerite. 
  The 
  results 
  obtained 
  are 
  : 
  

   Si0 
  2 
  , 
  33-4:6 
  ; 
  CaO, 
  53-93 
  ; 
  F, 
  7*29 
  ; 
  MgO, 
  1/41 
  ; 
  magnetite, 
  2-13. 
  

   Alkalies 
  were 
  not 
  determined 
  on 
  any 
  of 
  the 
  samples 
  because 
  of 
  

   paucity 
  of 
  material. 
  Some 
  of 
  the 
  whiter, 
  chalky-looking 
  mate- 
  

   rial 
  gave 
  less 
  water 
  than 
  the 
  fresh 
  material, 
  several 
  different 
  

   samples 
  yielding 
  from 
  2 
  to 
  3 
  per 
  cent 
  H 
  2 
  instead 
  of 
  the 
  5 
  to 
  

   6 
  per 
  cent 
  given 
  in 
  the 
  above 
  analysis. 
  Whether 
  this 
  repre- 
  

   sents 
  an 
  alteration 
  of 
  the 
  custerite 
  or 
  a 
  much 
  impurer 
  sample 
  

   could 
  not 
  be 
  determined 
  on 
  the 
  scanty 
  material 
  available. 
  

  

  Interpretation 
  of 
  analysis. 
  — 
  The 
  ratios 
  derived 
  from 
  the 
  

   above 
  analytical 
  figures 
  can 
  be 
  interpreted 
  either 
  by 
  consider- 
  

   ing 
  that 
  the 
  small 
  amount 
  of 
  magnesia 
  belongs 
  to 
  the 
  custerite 
  

   or 
  that 
  it 
  represents 
  admixed 
  diopside. 
  These 
  alternatives 
  are 
  

   shown 
  in 
  the 
  table 
  below 
  : 
  

  

  