﻿A. 
  P. 
  lioness 
  — 
  Etching 
  Figures 
  of 
  Beryl. 
  225 
  

  

  rilj 
  acts 
  slightly 
  upon 
  beryl, 
  failed 
  to 
  produce 
  the 
  slightest 
  

   trace 
  of 
  etch 
  figures 
  on 
  any 
  of 
  the 
  forms, 
  although 
  the 
  crystal 
  

   was 
  immersed 
  in 
  the 
  boiling 
  acid 
  for 
  an 
  hour 
  or 
  more. 
  When 
  

   plunged 
  into 
  fused 
  sodium 
  hydroxide 
  for 
  only 
  a 
  few 
  seconds, 
  

   the 
  crystal 
  was 
  well 
  etched 
  with 
  distinct 
  figures. 
  The 
  base 
  

   and 
  prism 
  etched 
  with 
  equal 
  rapidity, 
  the 
  base 
  figures 
  appear- 
  

   ing 
  circular 
  in 
  their 
  primitive 
  stage 
  of 
  growth, 
  but 
  gradually 
  

   becoming 
  hexagonal 
  as 
  solution 
  continued. 
  (See 
  fig. 
  1.) 
  The 
  

   figures 
  are 
  of 
  two 
  kinds 
  ; 
  the 
  first 
  are 
  hexagonal 
  pits 
  meeting 
  

   in 
  a 
  point 
  and 
  formed 
  by 
  six 
  faces 
  lying 
  in 
  the 
  zone 
  of 
  the 
  

   first 
  order 
  pyramid 
  and 
  the 
  base 
  ; 
  the 
  second 
  are 
  similar 
  six- 
  

   sided 
  forms 
  possessing 
  a 
  basal 
  plane. 
  The 
  figures 
  are 
  regular 
  

   hexagonal 
  forms 
  with 
  their 
  margins 
  parallel 
  to 
  the 
  intersection 
  

   1011/0001, 
  and 
  are 
  symmetrical 
  to 
  six 
  vertical 
  planes. 
  

  

  Etching 
  toith 
  Sodium 
  hydroxide. 
  

  

  Prism. 
  — 
  The 
  unit 
  prism, 
  1010, 
  was 
  beautifully 
  etched 
  after 
  

   immersion 
  in 
  the 
  fused 
  sodium 
  hydroxide 
  to 
  the 
  extent 
  of 
  

   fifteen 
  seconds. 
  Etchings 
  could 
  be 
  distinctly 
  seen 
  after 
  the 
  

   first 
  few 
  seconds, 
  but 
  they 
  appeared 
  as 
  tiny 
  cubical 
  forms, 
  very 
  

   similar 
  to 
  the 
  natural 
  etchings 
  on 
  the 
  1010 
  form 
  of 
  beryl 
  from 
  

   Columbia, 
  S. 
  A., 
  and 
  evenly 
  distributed 
  over 
  the 
  face. 
  The 
  

   ultimate 
  stage, 
  reached 
  after 
  the 
  solvent 
  had 
  acted 
  upon 
  the 
  

   face 
  for 
  about 
  fifteen 
  seconds, 
  revealed 
  well-defined 
  regular 
  

   quadrilateral 
  pits, 
  elongated 
  in 
  the 
  direction 
  of 
  the 
  c 
  axis 
  (fig. 
  

   2). 
  The 
  two 
  longer 
  sides 
  are 
  slightly 
  bulging, 
  while 
  the 
  ends 
  

   of 
  the 
  figures 
  are 
  bounded 
  by 
  two 
  short 
  straight 
  lines, 
  in 
  most 
  

   cases, 
  extending 
  at 
  right 
  angles 
  to 
  the 
  c 
  axis 
  of 
  the 
  crystal 
  and 
  

   the 
  longer 
  boundaries 
  of 
  the 
  figure. 
  In 
  a 
  few 
  cases, 
  these 
  

   shorter 
  lines 
  are 
  slightly 
  inclined 
  to 
  the 
  prism 
  edge, 
  but 
  this 
  is 
  

   exceptional 
  and 
  is 
  probably 
  due 
  to 
  surface 
  irregularities. 
  The 
  

   figures 
  occurring 
  on 
  the 
  unit 
  prism, 
  1010, 
  are 
  of_ 
  two 
  kinds, 
  — 
  

   those 
  terminated 
  by 
  a 
  plain 
  parallel 
  to 
  m 
  1010, 
  and 
  those 
  

   terminated 
  by 
  an 
  edge. 
  The 
  former 
  are 
  bounded 
  by 
  two 
  long 
  

   faces 
  parallel 
  to 
  the 
  prism 
  edges, 
  and 
  by 
  two 
  shorter 
  planes 
  in 
  

   zone 
  of 
  the 
  base 
  and 
  first 
  order 
  pyramid. 
  The 
  lateral 
  faces 
  

   are 
  truncated 
  by 
  a 
  fifth 
  plane 
  parallel 
  to 
  the 
  prism 
  face 
  etched 
  ; 
  

   this 
  face 
  is 
  also 
  quadrilateral, 
  very 
  much 
  like 
  the 
  outline 
  of 
  

   the 
  figure, 
  except 
  for 
  the 
  fact 
  that 
  its 
  longer 
  boundaries 
  are 
  

   not 
  curved 
  as 
  are 
  those 
  of 
  the 
  figure 
  itself. 
  The 
  figures 
  are 
  

   symmetrical 
  to 
  two 
  planes, 
  one 
  vertical, 
  and 
  one 
  horizontal, 
  

   which 
  accords 
  with 
  the 
  type. 
  

  

  Pyramids. 
  — 
  The 
  unit 
  second-order 
  pyramid, 
  when 
  immersed 
  

   in 
  fused 
  sodium 
  hydroxide, 
  turned 
  glassy 
  in 
  appearance 
  and 
  

   gradually 
  disappeared, 
  but 
  not 
  the 
  slightest 
  trace 
  of 
  an 
  etch- 
  

   ing 
  could 
  be 
  detected, 
  although 
  the 
  face 
  was 
  repeatedly 
  ex- 
  

  

  