﻿166 
  E. 
  V. 
  Shannon 
  — 
  Bismutoplagionite. 
  

  

  Akt. 
  XI. 
  — 
  Bismutoplagionite, 
  A 
  New 
  Mineral; 
  by 
  Eakl 
  

   V. 
  Shannon, 
  U. 
  S. 
  National 
  Museum. 
  1 
  

  

  Some 
  specimens 
  forwarded 
  to 
  the 
  U. 
  S. 
  National 
  

   Museum 
  for 
  examination 
  and 
  report 
  by 
  Mr. 
  Tim 
  McCar- 
  

   thy 
  of 
  Wickes, 
  Montana, 
  contained 
  a 
  gray, 
  metallic 
  min- 
  

   eral 
  which 
  was 
  identified 
  by 
  Mr. 
  W. 
  F. 
  Foshag 
  as 
  a 
  

   sulphide 
  of 
  lead 
  and 
  bismuth. 
  As 
  the 
  mineral 
  appeared 
  

   to 
  be 
  of 
  more 
  than 
  ordinary 
  interest, 
  the 
  sender 
  was 
  

   asked 
  for 
  a 
  sufficient 
  quantity 
  of 
  the 
  material 
  for 
  detailed 
  

   investigation 
  which, 
  when 
  received, 
  was 
  turned 
  over 
  to 
  

   the 
  writer 
  for 
  study. 
  Enough 
  of 
  the 
  gray 
  bismuth 
  min- 
  

   eral 
  was 
  secured 
  for 
  an 
  analysis 
  which 
  indicated 
  that 
  the 
  

   mineral 
  is 
  a 
  new 
  species 
  having 
  the 
  composition 
  of 
  a 
  

   plagionite 
  in 
  which 
  the 
  antimony 
  is 
  almost 
  entirely 
  re- 
  

   placed 
  by 
  bismuth. 
  The 
  name 
  bismutoplagionite 
  indi- 
  

   cates 
  this 
  chemical 
  relationship. 
  

  

  Nothing 
  is 
  known 
  regarding 
  the 
  locality 
  of 
  the 
  mineral 
  

   other 
  than 
  that 
  the 
  specimens 
  were 
  sent 
  from 
  Wickes, 
  

   Montana, 
  but 
  it 
  is 
  presumed 
  that 
  they 
  came 
  from 
  some- 
  

   where 
  in 
  that 
  immediate 
  vicinity. 
  Wickes 
  is 
  a 
  small 
  min- 
  

   ing 
  town 
  in 
  Jefferson 
  County, 
  about 
  10 
  miles 
  southwest 
  

   of 
  Helena. 
  

  

  The 
  specimens 
  consist 
  in 
  large 
  part 
  of 
  coarse 
  granular 
  

   pyrite, 
  each 
  grain 
  being 
  a 
  well-defined 
  cubic 
  crystal 
  with 
  

   the 
  corners 
  truncated 
  by 
  octahedral 
  planes. 
  The 
  bis- 
  

   muth 
  mineral 
  occurs 
  in 
  small, 
  indistinctly 
  fibrous 
  masses 
  

   intergrown 
  with 
  pyrite 
  in 
  aggregates 
  up 
  to 
  one 
  inch 
  in 
  

   diameter. 
  Much 
  of 
  the 
  ore 
  contains 
  a 
  soft, 
  scaly, 
  mica- 
  

   ceous 
  mineral 
  apparently 
  sericite. 
  The 
  masses 
  of 
  pyrite 
  

   contain 
  also 
  in 
  places 
  small 
  masses 
  of 
  galena, 
  tetrahedrite 
  

   and 
  chalcopyrite, 
  and 
  small 
  prismatic 
  crystals 
  of 
  trans- 
  

   parent 
  to 
  milky 
  quartz. 
  

  

  In 
  appearance 
  the 
  new 
  mineral 
  does 
  not 
  differ 
  from 
  

   many 
  of 
  the 
  other 
  sulphosalts 
  of 
  lead. 
  In 
  color 
  it 
  is 
  

   slightly 
  bluish 
  lead-gray. 
  The 
  aggregates 
  are 
  indis- 
  

   tinctly 
  fibrous, 
  the 
  fibers 
  curving 
  around 
  pyrite 
  or 
  quartz 
  

   crystals, 
  which, 
  when 
  removed, 
  leave 
  molds 
  in 
  the 
  bis- 
  

   muth 
  mineral. 
  There 
  is 
  a 
  rather 
  ill-defined 
  cleavage 
  par- 
  

   allel 
  to 
  the 
  elongation. 
  In 
  one 
  specimen 
  a 
  small 
  cavity 
  

   between 
  pyrite 
  crystals 
  contained 
  brilliant, 
  deeply 
  stri- 
  

  

  1 
  Published 
  by 
  permission 
  of 
  the 
  Secretary 
  of 
  the 
  Smithsonian 
  Institution. 
  

  

  