﻿134 
  Rogers 
  — 
  Sphalerite 
  Crystals 
  of 
  a 
  Peculiar 
  Habit. 
  

  

  Art. 
  XII. 
  — 
  Sphalerite 
  Crystals 
  of 
  a 
  'peculiar 
  habit 
  and 
  

   with 
  one 
  New 
  Form, 
  from 
  Galena, 
  Kansas 
  ; 
  by 
  Austin 
  F. 
  

   Kogers.* 
  

  

  The 
  sphalerite 
  crystals 
  usually 
  found 
  in 
  the 
  lead 
  and 
  zinc 
  

   district 
  of 
  southeastern 
  Kansas 
  and 
  southwestern 
  Missouri 
  

   are 
  those 
  of 
  the 
  ordinary 
  types 
  which 
  are 
  tetrahedral 
  in 
  aspect. 
  

   The 
  commonest 
  of 
  these 
  types 
  is 
  thatjwhich 
  exhibits 
  the 
  fol- 
  

   lowing 
  combination 
  : 
  o 
  (111) 
  1, 
  o, 
  (111) 
  1, 
  a 
  (100) 
  i-i. 
  Of 
  these 
  

   forms 
  the 
  negative 
  tetrahedron 
  o 
  / 
  is 
  usually 
  the 
  predominant 
  

   one. 
  During 
  the 
  past 
  summer 
  some 
  crystals 
  of 
  a 
  peculiar 
  habit 
  

   were 
  obtained 
  from 
  this 
  region, 
  a 
  description 
  of 
  which 
  seems 
  

   worthy 
  otf 
  publication. 
  They 
  were 
  collected 
  by 
  the 
  writer 
  at 
  

   the 
  Tennessee 
  Prairie 
  mines 
  five 
  miles 
  south 
  of 
  Galena, 
  Kansas. 
  

  

  1 
  take 
  pleasure 
  in 
  expressing 
  my 
  thanks 
  to 
  Mr. 
  Clark, 
  superin- 
  

   tendent 
  of 
  the 
  mines, 
  for 
  his 
  kindness 
  in 
  allowing 
  free 
  access 
  

   to 
  the 
  ore 
  bins 
  and 
  dump 
  piles. 
  

  

  The 
  crystals 
  are 
  reddish-brown 
  in 
  color 
  and 
  vary 
  in 
  size 
  

   from 
  one-half 
  to 
  three 
  centimeters 
  in 
  longest 
  diameter. 
  They 
  

   are 
  found 
  as 
  isolated 
  crystals 
  in 
  a 
  dark 
  clayey 
  siliceous 
  matrix 
  

   and 
  show 
  no 
  attachment. 
  The 
  associated 
  minerals 
  include 
  

   dolomite, 
  pyrite, 
  and 
  chalcopyrite, 
  the 
  two 
  former 
  of 
  which 
  

   occur 
  in 
  considerable 
  quantities. 
  

  

  The 
  peculiarity 
  of 
  these 
  crystals 
  is 
  that 
  they 
  are 
  abnormally 
  

   developed, 
  being 
  shortened 
  in 
  the 
  direction 
  of 
  one 
  of 
  the 
  octa- 
  

   hedral 
  interaxes. 
  The 
  predominant 
  faces 
  are 
  those 
  of 
  the 
  

   rhombic 
  dodecahedron. 
  In 
  consequence 
  of 
  this 
  abnormal 
  

   development 
  the 
  crystals 
  appear 
  as 
  combinations 
  of 
  a 
  rhombo- 
  

   hedron 
  with 
  the 
  prism 
  of 
  the 
  second 
  order. 
  On 
  account 
  of 
  

   the 
  presence 
  of 
  certain 
  faces 
  soon 
  to 
  be 
  described 
  the 
  crystals 
  

   have 
  a 
  decided 
  hemimorphic 
  aspect 
  in 
  the 
  direction 
  of 
  the 
  

   above 
  mentioned 
  axis. 
  Here, 
  then, 
  we 
  have 
  an 
  isometric 
  crys- 
  

   tal 
  possessing 
  apparent 
  lower 
  symmetry, 
  namely, 
  that 
  of 
  the 
  

   rhombohedral-hemimorphic 
  group. 
  Figures 
  1 
  and 
  2 
  represent 
  

   crystals 
  of 
  this 
  habit. 
  Figure 
  1 
  is 
  an 
  ordinary 
  clinographic 
  

   projection, 
  which 
  is 
  shortened 
  in 
  the 
  direction_of 
  the 
  octa- 
  

   hedral 
  interaxis 
  connecting 
  the 
  faces 
  (111) 
  and 
  (111). 
  Figure 
  

  

  2 
  is 
  an 
  orthographic 
  projection 
  with 
  (111) 
  as 
  the 
  plane 
  of 
  pro- 
  

   jection. 
  Truncating 
  half 
  of 
  the 
  dodecahedral 
  edges 
  are 
  the 
  

   faces 
  of 
  a 
  hemi-tetragonal 
  trisoctahedron, 
  the 
  form 
  a 
  (833), 
  f-f 
  

   which 
  seems 
  to 
  be 
  new 
  for 
  sphalerite. 
  As 
  these 
  faces 
  and 
  

   their 
  combination 
  edges 
  with 
  d 
  (110) 
  are 
  somewhat 
  rounded 
  

   and 
  the 
  faces 
  are 
  dull, 
  no 
  measurements 
  with 
  the 
  reflecting 
  

  

  * 
  Published 
  by 
  permission 
  of 
  the 
  Director 
  of 
  the 
  University 
  Geological 
  Survey 
  

   of 
  Kansas 
  in 
  advance 
  of 
  the 
  final 
  Report 
  on 
  Lead 
  and 
  Zinc. 
  

  

  