﻿L. 
  V. 
  Pirsson 
  — 
  Mmeralogical 
  Notes. 
  

  

  409 
  

  

  good 
  measurements, 
  some 
  of 
  which 
  were 
  repeated 
  on 
  several 
  

   crystals. 
  

  

  The 
  following 
  table 
  shows 
  the 
  identification 
  of 
  the 
  forms 
  by 
  

   calculated 
  and 
  measured 
  angles. 
  For 
  the 
  calculated 
  the 
  ele- 
  

   ments 
  of 
  Cooke 
  are 
  taken, 
  in 
  which 
  

  

  a:c 
  = 
  1 
  : 
  3-4951. 
  c^R 
  (0001 
  A 
  l0il) 
  = 
  lQ 
  o 
  05'. 
  

  

  

  Forms. 
  

  

  Calc. 
  

  

  Meas. 
  

  

  c 
  A.r 
  

  

  0001 
  ,v 
  1011 
  

  

  103° 
  55' 
  

  

  104° 
  

  

  C 
  /v 
  (j) 
  

  

  0001~4-0-4'13 
  

  

  51 
  09 
  

  

  51° 
  06' 
  

  

  c~y 
  

  

  0001*2025 
  

  

  58 
  13 
  

  

  58 
  05 
  

  

  C 
  a2 
  

  

  0001 
  ,s 
  1013 
  

  

  53 
  22£ 
  

  

  53 
  48 
  

  

  c~p 
  

  

  0001^1124 
  

  

  60 
  13-J- 
  

  

  60 
  35 
  

  

  z*p 
  

  

  1013^1124 
  

  

  25 
  54 
  

  

  25 
  22 
  

  

  c~X 
  

  

  0001^1122 
  

  

  74 
  05 
  

  

  74 
  10 
  

  

  The 
  form 
  1-2 
  (1122) 
  was 
  also 
  identified 
  by 
  the 
  fact 
  that 
  it 
  

   lies 
  in 
  the 
  zone 
  between 
  ^ 
  (1013) 
  and 
  r, 
  R, 
  (1011). 
  

  

  5. 
  Mordenite. 
  — 
  The 
  author 
  desires 
  to 
  correct 
  a 
  small 
  error 
  

   which 
  crept 
  into 
  the 
  determination 
  of 
  the 
  constants 
  of 
  this 
  

   mineral 
  as 
  given 
  in 
  this 
  Journal, 
  xl, 
  page 
  236. 
  These 
  should 
  

   read 
  

  

  d 
  : 
  b 
  : 
  c 
  : 
  ; 
  0-40099 
  : 
  1 
  : 
  0-42792 
  angle 
  /?=88° 
  29' 
  46* 
  

  

  instead 
  of 
  the 
  figures 
  there 
  given, 
  which 
  are 
  

  

  d: 
  b- 
  c 
  : 
  : 
  0-40101 
  : 
  1 
  ; 
  0-42623 
  angle 
  8=88° 
  30' 
  30'. 
  

  

  Mineralogical 
  Laboratory, 
  Sheffield 
  Scientific 
  School, 
  

   New 
  Haven, 
  Nov., 
  1890. 
  

  

  