﻿E. 
  Y. 
  Shannon 
  — 
  Crystals 
  of 
  Pyromorp 
  kite. 
  325 
  

  

  Art. 
  XXX. 
  — 
  Crystals 
  of 
  Pyromorphite; 
  by 
  Earl 
  Y. 
  Shannon. 
  

  

  1. 
  Pyromorphite 
  from 
  the 
  Caledonia 
  Mine, 
  Coeur 
  d? 
  Alene 
  

  

  District 
  L 
  Idaho. 
  

  

  'j 
  

  

  Certain 
  specimens 
  showing 
  hexagonal 
  crystals 
  of 
  some 
  

   secondary 
  lead 
  mineral 
  were 
  collected 
  by 
  the 
  author 
  in 
  

   February, 
  1915, 
  in 
  the 
  Caledonia 
  Mine 
  near 
  Wardner, 
  Idaho. 
  

   Recent 
  study 
  has 
  shown 
  this 
  mineral 
  to 
  be 
  pyromorphite 
  but, 
  

   although 
  the 
  crystals 
  are 
  quite 
  simple 
  and 
  show 
  no 
  new 
  forms, 
  

   the 
  habit 
  and 
  mode 
  of 
  occurrence 
  are 
  somewhat 
  unusual. 
  

  

  Occurrence. 
  — 
  The 
  Caledonia 
  vein 
  consists 
  in 
  its 
  unaltered 
  

   portion 
  of 
  a 
  rather 
  large 
  body 
  of 
  pure, 
  fine-grained, 
  argentif- 
  

   erous 
  galena 
  with 
  smaller 
  amounts 
  of 
  chalcopyrite 
  and 
  tetrahe- 
  

   drite. 
  From 
  the 
  surface 
  downward 
  for 
  some 
  800 
  feet 
  the 
  vein 
  

   maintains 
  a 
  rather 
  high 
  dip, 
  but 
  on 
  the 
  900-foot 
  level 
  it 
  flattens 
  

   out 
  into 
  an 
  almost 
  horizontal 
  position 
  and 
  forms 
  a 
  'blanket' 
  

   ore-body 
  of 
  considerable 
  size 
  and 
  richness. 
  Below 
  this 
  level 
  the 
  

   vein 
  is 
  traceable 
  as 
  a 
  gouge-filled 
  fissure 
  which 
  has 
  not 
  been 
  

   shown 
  to 
  contain 
  any 
  commercial 
  ore. 
  The 
  inclosing 
  rock 
  con- 
  

   sists 
  of 
  a 
  much 
  crushed 
  white 
  quartzite 
  belonging 
  to 
  the 
  Burke 
  

   division 
  of 
  the 
  Belt 
  Series 
  of 
  sediments 
  of 
  Algonkian 
  age. 
  No 
  

   igneous 
  rocks 
  are 
  known 
  from 
  the 
  vicinity. 
  The 
  zones 
  of 
  

   oxidation 
  and 
  secondary 
  enrichment 
  were 
  well 
  defined 
  in 
  the 
  

   portion 
  of 
  the 
  vein 
  above 
  the 
  700-foot 
  level. 
  In 
  the 
  oxidized 
  

   ore, 
  pyromorphite, 
  of 
  the 
  pale 
  green 
  color 
  common 
  in 
  the 
  

   Coeur 
  d'Alene 
  District, 
  occurred 
  in 
  crystal 
  masses 
  of 
  extra- 
  

   ordinary 
  size 
  and 
  beauty, 
  associated 
  with 
  cerussite, 
  massicot, 
  

   bindheimire, 
  and 
  native 
  silver. 
  The 
  material 
  here 
  described 
  is 
  

   totally 
  unlike 
  the 
  green 
  pyromorphite 
  in 
  appearance 
  and 
  was 
  

   not 
  noted 
  in 
  the 
  oxidized 
  nor 
  in 
  the 
  secondary 
  sulphide 
  ore. 
  

   The 
  crystals 
  commonly 
  occur 
  deposited 
  in 
  cracks 
  in 
  masses 
  of 
  

   unaltered 
  galena 
  or 
  in 
  the 
  wall-rock 
  adjacent 
  to 
  such 
  masses 
  of 
  

   galena, 
  from 
  the 
  500-foot 
  to 
  the 
  900-foot 
  level. 
  There 
  is 
  no 
  

   other 
  secondary 
  lead 
  mineral 
  associated 
  with 
  the 
  pyromorphite 
  

   which 
  has 
  here 
  apparently 
  formed 
  directly 
  from 
  the 
  galena 
  

   without 
  the 
  intermediate 
  compounds, 
  anglesite 
  and 
  cerussite. 
  

  

  Pyromorphite 
  in 
  this 
  district 
  is 
  a 
  characteristic 
  mineral 
  in 
  

   the 
  extreme 
  upper 
  portion 
  of 
  the 
  oxidized 
  zone. 
  Ordinary 
  

   green 
  pyromorphite 
  has 
  not 
  been 
  found 
  here 
  at 
  a 
  greater 
  depth 
  

   than 
  300 
  feet 
  below 
  the 
  surface. 
  No 
  specimen 
  is 
  known, 
  from 
  

   the 
  district, 
  showing 
  green 
  pyromorphite 
  associated 
  with 
  galena. 
  

   It 
  is 
  of 
  importance 
  to 
  note 
  that 
  the 
  mineral 
  described 
  below 
  

   occurs 
  in 
  some 
  abundance 
  in 
  the 
  lowest 
  ore 
  opened, 
  900 
  feet, 
  

   vertically, 
  below 
  the 
  surface. 
  

  

  