﻿2l8 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Many 
  of 
  the 
  specimens 
  formerly 
  obtained 
  showed 
  large 
  and 
  beau- 
  

   tiful 
  calcite 
  combinations. 
  Those 
  which 
  through 
  Mr 
  Hawkins's 
  

   kindness 
  are 
  available 
  consist 
  of 
  built-up 
  individuals 
  formed 
  of 
  

   two 
  superposed 
  types 
  in 
  parallel 
  position 
  and 
  evidently 
  represent- 
  

   ing 
  two 
  generations 
  of 
  calcite 
  deposition. 
  The 
  compound 
  indi- 
  

   viduals 
  average 
  30 
  millimeters 
  in 
  vertical 
  length. 
  The 
  crystal 
  

   elements 
  of 
  these 
  compound 
  groupings 
  which 
  represent 
  the 
  earlier 
  

   generation 
  are 
  rhombohedral 
  in 
  habit. 
  In 
  some 
  instances 
  this 
  habit 
  

   occurred 
  sufficiently 
  free 
  from 
  the 
  superimposing 
  secondary 
  habit 
  

   to 
  admit 
  of 
  the 
  determination 
  of 
  the 
  modifying 
  forms. 
  The 
  sim- 
  

   ple 
  individual 
  of 
  this 
  generation 
  is 
  shown 
  in 
  figure 
  i 
  and 
  consists 
  

   of 
  the 
  negative 
  rhombohedrons 
  ^. 
  (01 
  12) 
  and 
  //. 
  (0881) 
  modified 
  

   by 
  the 
  forms 
  a 
  (1120), 
  m.(404i), 
  K:(2i3i), 
  O: 
  (8.5. 
  13.3) 
  and 
  

   s 
  :( 
  17.13. 
  30.4), 
  the 
  latter 
  of 
  which 
  is 
  new 
  to 
  the 
  species. 
  The 
  

   crystals 
  of 
  this 
  generation 
  which 
  are 
  slightly 
  more 
  purplish 
  in 
  

   color 
  and 
  more 
  transparent 
  than 
  those 
  of 
  the 
  superposed 
  second 
  

   generation 
  in 
  several 
  instances 
  appear 
  as 
  phantoms 
  within 
  the 
  

   latter. 
  The 
  superposed 
  crystals 
  of 
  the 
  second 
  generation, 
  which 
  

   are 
  transparent 
  t'o 
  translucent 
  and 
  slightly 
  yellowish 
  in 
  color, 
  are 
  

   scalenohedral 
  in 
  habit. 
  They 
  are 
  supierimposed 
  in 
  parallel 
  position 
  

   upon 
  the 
  lateral 
  solid 
  angles 
  of 
  the 
  rhombohedral 
  habit 
  of 
  the 
  

   s:(i7.i3.30.4), 
  the 
  latter 
  of 
  which 
  is 
  new 
  to 
  the 
  species. 
  The 
  

   first 
  generation 
  in 
  the 
  manner 
  shown 
  in 
  figures 
  2a 
  and 
  'b. 
  The 
  

  

  - 
  8 
  

   dominant 
  form 
  is 
  a 
  new 
  negative 
  scalenohedron 
  - 
  - 
  R 
  - 
  = 
  

  

  (3. 
  13. 
  16.8)) 
  to 
  which 
  the 
  letter 
  t 
  has 
  been 
  assigned. 
  The 
  scaleno- 
  

   hedral 
  habit 
  is 
  terminated 
  by 
  the 
  negative 
  rhombohedron 
  y. 
  (0554) 
  

  

  = 
  _ 
  5 
  j^ 
  the 
  two 
  forms 
  lying 
  in 
  the 
  zone 
  [0554.1120]. 
  In 
  ad- 
  

  

  4 
  

   dition 
  to 
  the 
  foregoing 
  the 
  new 
  scalenohedron 
  lies 
  in 
  zone 
  with 
  

  

  the 
  planes 
  1102 
  = 
  ^. 
  and 
  0881 
  = 
  //. 
  both 
  of 
  which 
  are 
  present 
  in 
  

   considerable 
  development 
  on 
  the 
  rhombohedral 
  crystals 
  of 
  the 
  first 
  

   generation. 
  In 
  general 
  habit 
  the 
  superimposed 
  crystals 
  conform 
  

   closely 
  to 
  that 
  shown 
  in 
  figure 
  552B 
  of 
  Dana's 
  System 
  of 
  Min- 
  

   eralogy, 
  fifth 
  edition, 
  from 
  Bergen 
  Hill. 
  The 
  calculated 
  angles 
  

  

  7 
  3 
  — 
  

  

  for 
  the 
  negative 
  scalenohedron 
  - 
  - 
  R-= 
  (7.35.42.20) 
  assigned 
  

  

  to 
  this 
  combination 
  are 
  X 
  = 
  87° 
  14', 
  Y=:i5° 
  52' 
  and 
  Z 
  = 
  

   68° 
  14'. 
  The 
  measured 
  values 
  of 
  the 
  angles 
  Y 
  and 
  Z 
  for 
  the 
  nega- 
  

  

  - 
  Q 
  

  

  tive 
  scalenohedron 
  t 
  = 
  — 
  - 
  R-= 
  (3. 
  13. 
  16.8) 
  are: 
  

  

  4 
  5 
  

   Y= 
  17° 
  46'; 
  17° 
  18'; 
  17° 
  48' 
  and 
  17° 
  11'. 
  

  

  • 
  Z 
  = 
  69° 
  II'; 
  69° 
  20'; 
  68° 
  51' 
  and 
  69° 
  3'. 
  

  

  