﻿of 
  RhyoUtefrom 
  Glade 
  Greek, 
  Wyoming. 
  43 
  

  

  rhombohedrons 
  j, 
  3032, 
  f 
  and 
  a, 
  0332, 
  -f 
  and 
  narrow 
  tra- 
  

   pezohedral 
  faces 
  N 
  and 
  L 
  ± 
  f-f, 
  which 
  lie 
  in 
  the 
  zone 
  

   between 
  j 
  and 
  a 
  and 
  also 
  in 
  the 
  zone 
  s, 
  r 
  and 
  m. 
  The 
  

   rhombohedrons 
  ^ 
  and 
  a 
  are 
  not 
  mentioned 
  by 
  G. 
  Rose* 
  in 
  his 
  

   classical 
  paper 
  on 
  quartz. 
  Des 
  Cloizeaux,f 
  in 
  his 
  very 
  exten- 
  

   sive 
  monograph 
  on 
  the 
  crystallization 
  of 
  quartz 
  was 
  the 
  first 
  

   to 
  observe 
  these 
  forms. 
  During 
  his 
  investigation 
  he 
  added 
  

   twenty-one 
  new 
  positive 
  rhombohedrons 
  to 
  the 
  seven 
  which 
  

   were 
  already 
  known. 
  Of 
  the 
  + 
  f 
  rhombohedron 
  j 
  he 
  says 
  : 
  

   " 
  this 
  has 
  been 
  found 
  on 
  two 
  crystals 
  from 
  Traversella, 
  on 
  a 
  

   large 
  crystal 
  from 
  Brazil, 
  and 
  upon 
  a 
  little 
  crystal 
  from 
  Ala. 
  

   Its 
  measurement 
  is 
  a 
  little 
  uncertain 
  as 
  it 
  always 
  presents 
  

   rounded 
  faces. 
  Among 
  the 
  considerations 
  which 
  favor 
  the 
  

   acceptance 
  of 
  this 
  rhombohedron 
  is 
  the 
  occurrence 
  of 
  the 
  

   negative 
  f 
  form." 
  He 
  also 
  added 
  twenty-five 
  new 
  negative 
  

   rhombohedrons 
  to 
  the 
  five 
  which 
  were 
  already 
  known. 
  Of 
  

   the 
  -f 
  rhombohedron 
  a 
  he 
  says 
  : 
  "this 
  rhombohedron 
  has 
  been 
  

   observed 
  upon 
  twenty-three 
  crystals 
  from 
  Traversella, 
  and 
  upon 
  

   many 
  crystals 
  from 
  Valais. 
  The 
  mean 
  of 
  fifty-four 
  measure- 
  

   ments, 
  in 
  spite 
  of 
  a 
  slight 
  rounding 
  of 
  the 
  faces, 
  leaves 
  no 
  doubt 
  

   of 
  its 
  symbol." 
  On 
  the 
  crystals 
  from 
  Glade 
  Creek 
  both 
  j 
  

   and 
  a 
  are 
  perfect 
  as 
  regards 
  luster 
  and 
  freedom 
  from 
  stria- 
  

   tions. 
  They 
  may 
  be 
  detected 
  on 
  nearly 
  all 
  crystals 
  and 
  some- 
  

   times 
  they 
  are 
  largely 
  developed. 
  Figures 
  1 
  and 
  2 
  represent 
  

   the 
  relative 
  size 
  and 
  development 
  of 
  these 
  faces 
  on 
  two 
  of 
  the 
  

   transparent 
  stout 
  crystals 
  which 
  were 
  detached 
  for 
  measurement, 
  

   and 
  figure 
  3, 
  the 
  greater 
  development 
  of 
  them 
  at 
  one 
  end 
  of 
  a 
  

   slender 
  white 
  prism. 
  In 
  the 
  majority 
  of 
  cases, 
  the 
  edges 
  

   between 
  j 
  and 
  a 
  are 
  replaced 
  by 
  trapezohedral 
  faces 
  having 
  the 
  

   simple 
  parameter 
  relation 
  f-f 
  ; 
  moreover 
  all 
  of 
  the 
  four 
  pos- 
  

   sible 
  trapezohedral 
  forms 
  with 
  the 
  above 
  parameter 
  relation 
  

   were 
  observed. 
  On 
  the 
  right-handed 
  crystal 
  represented 
  in 
  

   fig. 
  1, 
  ]ST, 
  2132, 
  +?- 
  f-f, 
  and 
  JNT, 
  3212, 
  -r 
  f- 
  2 
  3 
  occur, 
  while 
  

   onthe 
  left-handed 
  crystals 
  represented 
  in 
  figs. 
  2 
  and 
  3, 
  L, 
  

   8122, 
  +1 
  f-f 
  and 
  L 
  v 
  , 
  1232, 
  -I 
  f-f 
  occur. 
  DesCloizeaux 
  

   also 
  observed 
  these 
  forms 
  and 
  says 
  of 
  E" 
  + 
  f-f 
  "this 
  very 
  

   rare 
  form 
  has 
  been 
  observed 
  only 
  upon 
  the 
  very 
  remarkable 
  

   crystal 
  from 
  Brazil. 
  As 
  it 
  is 
  very 
  narrow 
  and 
  a 
  little 
  rounded 
  

   its 
  measurement 
  could 
  not 
  be 
  made 
  very 
  exactly 
  ; 
  however 
  its 
  

   angle 
  upon 
  r, 
  calculated 
  for 
  the 
  symbol 
  here 
  adopted, 
  differs 
  

   very 
  little 
  from 
  the 
  mean 
  of 
  the 
  observation 
  and 
  its 
  very 
  simple 
  

   symbol, 
  being 
  the 
  inverse 
  of 
  the 
  probable 
  face 
  L, 
  -f-f, 
  point 
  

   to 
  its 
  existence." 
  Of 
  L, 
  -f-f, 
  indicated 
  by 
  DesCloizeaux 
  

   with 
  (?) 
  as 
  a 
  probable 
  but 
  not 
  certain 
  form, 
  he 
  says 
  : 
  " 
  this 
  very 
  

   simple 
  symbol 
  can 
  be 
  applied 
  to 
  a 
  face 
  observed 
  upon 
  many 
  

  

  * 
  Abh. 
  Akad. 
  Berlin, 
  1844, 
  p. 
  211. 
  f 
  Ann. 
  Ch. 
  Phys., 
  1855, 
  p. 
  129. 
  

  

  