﻿328 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol. 
  44. 
  

  

  ground 
  displaymg 
  structures 
  wliich 
  to 
  my 
  mind 
  can 
  be 
  explained 
  

   only 
  on 
  the 
  supposition 
  that 
  it 
  was 
  imbedded 
  in 
  a 
  finer 
  ash-like 
  

   ground 
  which, 
  on 
  being 
  subjected 
  to 
  a 
  shearing 
  movement, 
  had 
  

   yielded, 
  giving 
  results 
  closely 
  simulating 
  the 
  flow 
  structure 
  produced 
  

   under 
  similar 
  conditions 
  in 
  terrestrial 
  rocks. 
  

  

  A 
  brecciated 
  structure 
  is 
  not 
  uncommon 
  in 
  meteorites. 
  Indeed, 
  

   the 
  mineral 
  constituents 
  of 
  stony 
  meteorites 
  are 
  more 
  common 
  in 
  a 
  

   fragmental 
  condition 
  than 
  otherwise. 
  A 
  true 
  breccia 
  structure 
  pro- 
  

   duced 
  b}^ 
  rock 
  fragments 
  imbedded 
  m 
  a 
  finer 
  ground, 
  as 
  is 
  the 
  case 
  

   of 
  the 
  stones 
  of 
  St. 
  Mesmin 
  and 
  Soko 
  Banja, 
  or 
  the 
  Mount 
  Joy 
  iron, 
  

   is 
  much 
  more 
  rare, 
  and 
  I 
  have 
  not 
  seen, 
  either 
  in 
  the 
  stone 
  itself 
  nor 
  

   in 
  written 
  descriptions, 
  anything 
  comparable 
  to 
  the 
  structure 
  I 
  have 
  

   attempted 
  to 
  describe 
  above. 
  If 
  I 
  am 
  right 
  m 
  my 
  interpretation 
  of 
  

   what 
  is 
  shown, 
  it 
  of 
  course 
  means 
  that 
  this 
  stone 
  was 
  once 
  a 
  portion 
  

   of 
  a 
  vastly 
  larger 
  mass 
  in 
  which 
  stresses 
  were 
  operative 
  as 
  in 
  the 
  

   moderately 
  deep-seated 
  portions 
  of 
  the 
  crust 
  of 
  our 
  own 
  earth. 
  The 
  

   occurence 
  differs 
  from 
  that 
  of 
  Chattonay, 
  as 
  described 
  by 
  Tscher- 
  

   mak, 
  in 
  that 
  iron 
  is 
  very 
  uniforixdy 
  distributed 
  throughout 
  the 
  ground, 
  

   while 
  only 
  the 
  sulphide 
  is 
  apparent 
  in 
  the 
  inclosure. 
  From 
  the 
  

   Orvinio 
  stone 
  it 
  differs 
  in 
  that 
  the 
  inclosure 
  is 
  not 
  of 
  the 
  same 
  mineral 
  

   nature 
  as 
  the 
  matrix, 
  containing 
  no 
  olivine 
  nor 
  metal, 
  but 
  consisting 
  

   wholly 
  of 
  the 
  pyroxene 
  and 
  iron 
  sulphides. 
  

  

  A 
  word 
  with 
  reference 
  to 
  the 
  iron 
  sulphide. 
  This 
  is 
  distributed 
  

   very 
  generall}^ 
  throughout 
  the 
  stone 
  both 
  m 
  small 
  particles, 
  as 
  is 
  the 
  

   metallic 
  portion, 
  and 
  also 
  in 
  larger 
  forms, 
  the 
  section 
  shown 
  in 
  figure 
  2, 
  

   plate 
  55, 
  wliich 
  is 
  some 
  15 
  cm, 
  by 
  10 
  cm. 
  in 
  dimension, 
  showing 
  seven 
  

   sulpliide 
  areas 
  varying 
  from 
  5 
  to 
  10 
  mm. 
  in 
  length 
  besides 
  innumerable 
  

   smaller 
  forms. 
  These 
  are 
  so 
  closely 
  associated 
  with 
  the 
  metallic 
  

   particles 
  as 
  to 
  be 
  practically, 
  and 
  m 
  some 
  cases 
  actually, 
  in 
  contact 
  

   with 
  them. 
  In 
  one 
  instance 
  an 
  area 
  of 
  sulpliide 
  about 
  3 
  mm. 
  in 
  

   length 
  and 
  1 
  mm. 
  broad 
  is 
  capped, 
  as 
  it 
  were, 
  at 
  either 
  end, 
  with 
  the 
  

   native 
  metal. 
  (PL 
  55, 
  fig. 
  3.) 
  In 
  other 
  cases 
  metal 
  and 
  sulphide 
  

   appear 
  mutually 
  intergrown. 
  The 
  matter 
  is 
  mentioned 
  m 
  detail 
  as 
  

   haVmg 
  some 
  bearing 
  upon 
  the 
  mineral 
  nature 
  of 
  the 
  sulphide, 
  it 
  

   being 
  usually 
  conceded 
  that 
  the 
  form 
  found 
  in 
  metallic 
  meteorites 
  

   is 
  the 
  monosulphide 
  truilite, 
  and 
  in 
  the 
  stony 
  forms, 
  pyrrhotite. 
  

   Recent 
  work 
  by 
  Dr. 
  E. 
  T. 
  Allen,^ 
  of 
  the 
  Carnegie 
  Geophysical 
  Labora- 
  

   tory, 
  shows 
  that 
  in 
  the 
  presence 
  of 
  an 
  excess 
  of 
  iron 
  onl}' 
  the 
  mono- 
  

   sulphide 
  is 
  possible, 
  and 
  it 
  would 
  hence 
  seem 
  probable 
  that 
  it 
  must 
  

   so 
  exist 
  in 
  the 
  stone 
  here 
  described. 
  It 
  is 
  possible, 
  however, 
  that 
  there 
  

   may 
  be 
  a 
  gradual 
  change 
  in 
  the 
  character 
  of 
  the 
  sulphide 
  as 
  the 
  dis- 
  

   tance 
  from 
  the 
  point 
  of 
  contact 
  mcreases, 
  the 
  monosulphide 
  (FeS) 
  

   forming 
  at 
  the 
  immediate 
  contact 
  and 
  this 
  grading 
  into 
  compounds 
  

   conforming 
  to 
  the 
  formula 
  FcnSn+l. 
  Separation 
  of 
  the 
  material 
  

   for 
  analysis 
  in 
  order 
  to 
  determine 
  this 
  point 
  is 
  obviously 
  impossible. 
  

  

  1 
  Amer. 
  Journ. 
  Sci., 
  vol. 
  33, 
  1912, 
  p. 
  212. 
  

  

  