﻿64:0 
  Palache 
  and 
  Graham 
  — 
  Crystallization 
  of 
  Willemite. 
  

  

  Fig. 
  1 
  shows 
  the 
  prevailing 
  type 
  with 
  the 
  prism 
  a 
  dominant 
  

   and 
  narrow 
  truncating 
  faces 
  of 
  m 
  ; 
  while 
  the 
  characteristic 
  

   terminal 
  planes 
  are 
  the 
  complementary 
  positive 
  third 
  order 
  

   rhombohedrons 
  x 
  and 
  y 
  and 
  the 
  first 
  order 
  rhombohedrons 
  r 
  

   and 
  n. 
  The 
  crystal 
  shown 
  in 
  fig. 
  2 
  has 
  in 
  addition 
  largely 
  

   developed 
  faces 
  of 
  the 
  negative 
  third 
  order 
  rhombohedrons 
  d, 
  

  

  Figs, 
  la, 
  16 
  

  

  2a, 
  26 
  

  

  3a, 
  36 
  

  

  D 
  and 
  q. 
  The 
  criterion 
  used 
  to 
  determine 
  a 
  common 
  position 
  

   for 
  the 
  various 
  measured 
  crystals 
  was 
  the 
  occurrence 
  of 
  the 
  

   third 
  order 
  rhombohedrons 
  k 
  and 
  <?, 
  one 
  or 
  both 
  .of 
  which 
  

   are 
  always 
  present, 
  and 
  by 
  producing 
  a 
  faint 
  striation 
  on 
  

   x 
  parallel 
  to 
  the 
  intersection 
  with 
  a, 
  give 
  a 
  sure 
  means 
  of 
  

   orientation. 
  The 
  forms 
  q 
  and 
  I 
  when 
  present 
  can 
  also 
  be 
  thus 
  

   used 
  without 
  ambiguity. 
  The 
  figures 
  are 
  representative 
  of 
  

   types 
  rather 
  than 
  particular 
  crystals 
  ; 
  although 
  there 
  is 
  much 
  

   variation 
  in 
  the 
  relative 
  size 
  of 
  the 
  different 
  forms, 
  the 
  draw- 
  

  

  