﻿44 
  Washington 
  — 
  Igneous 
  Hocks 
  from 
  Smyrna, 
  etc. 
  

  

  considerably 
  from 
  those 
  just 
  described. 
  Rosenbusch* 
  describes 
  

   rocks 
  from 
  this 
  locality 
  as 
  biotite-hypersthene-andesite. 
  I 
  was 
  

   unable 
  to 
  find 
  any 
  hypersthene 
  in 
  the 
  specimens 
  examined, 
  and 
  

   the 
  microphotograph 
  he 
  gives 
  resembles 
  very 
  much 
  my 
  sec- 
  

   tions 
  of 
  the 
  Pagos 
  rocks, 
  and 
  is 
  of 
  a 
  totally 
  different 
  character 
  

   from 
  all 
  of 
  those 
  of 
  the 
  Kara 
  Tash 
  rocks 
  sent 
  by 
  Mr. 
  Diller, 
  

   so 
  that 
  it 
  seems 
  probable 
  that 
  the 
  locality 
  of 
  his 
  specimen 
  is 
  

   incorrectly 
  given. 
  

  

  The 
  Kara 
  Tash 
  rocks 
  are 
  all 
  very 
  dark 
  and 
  compact, 
  show- 
  

   ing 
  numerous 
  small 
  glasiy 
  feldspars, 
  and 
  a 
  few 
  augite 
  and 
  

   biotite 
  phenocrysts 
  in 
  a 
  very 
  dark 
  brown 
  or 
  black, 
  highly 
  

   vitreous 
  groundmass. 
  Some 
  evidences 
  of 
  flow-structure 
  are 
  

   seen 
  in 
  the 
  hand 
  specimen 
  and 
  are 
  even 
  more 
  marked 
  in 
  the 
  

   mass, 
  judging 
  from 
  Mr. 
  Diller's 
  notes. 
  

  

  Under 
  the 
  microscope 
  the 
  very 
  well-shaped 
  feldspar 
  pheno- 
  

   crysts 
  are 
  seen 
  to 
  be 
  of 
  labradorite 
  a 
  trifle 
  more 
  basic 
  than 
  

   AbjAnj. 
  They 
  are 
  clear 
  and 
  fresh 
  and 
  show, 
  almost 
  without 
  

   exception, 
  twinning 
  lamellae, 
  while 
  zonal 
  structure 
  is 
  frequent. 
  

   Inclusions 
  are 
  not 
  very 
  abundant, 
  and 
  consist 
  mostly 
  of 
  small 
  

   spots 
  of 
  dusty 
  brownish 
  glass, 
  with 
  a 
  few 
  apatites. 
  The 
  very 
  

   pale 
  green 
  diopsides 
  are 
  highly 
  automorphic, 
  perfectly 
  fresh 
  

   and 
  contain 
  few 
  inclusions. 
  The 
  not 
  very 
  numerous 
  biotites 
  

   are 
  greenish 
  brown 
  and 
  perfectly 
  fresh, 
  even 
  incipient 
  altera- 
  

   tion 
  not 
  being 
  seen. 
  Some 
  large, 
  well-shaped 
  magnetite 
  grains 
  

   may 
  also 
  be 
  classed 
  among 
  the 
  phenocrysts. 
  The 
  very 
  abund- 
  

   ant 
  groundmass 
  is 
  highly 
  vitreous, 
  the 
  glass 
  being 
  quite 
  color- 
  

   less, 
  and 
  only 
  rare 
  small 
  crystals 
  of 
  augite, 
  feldspar, 
  magnetite 
  

   and 
  apatite 
  being 
  present. 
  It 
  is 
  chiefly 
  remarkable 
  for 
  the 
  

   very 
  great 
  abundance 
  of 
  trichites, 
  with 
  which 
  it 
  is 
  thickly 
  

   crowded. 
  By 
  far 
  the 
  greater 
  part 
  of 
  these 
  are 
  curved, 
  some- 
  

   times 
  to 
  a 
  high 
  degree, 
  but 
  some 
  straight 
  ones 
  are 
  seen. 
  

   Though 
  under 
  low 
  powers 
  they 
  seem 
  opaque, 
  yet 
  high 
  powers 
  

   show 
  the 
  majority 
  of 
  them 
  to 
  be 
  clear 
  and 
  colorless. 
  Those 
  

   which 
  seem 
  black 
  and 
  opaque 
  under 
  these 
  conditions 
  probably 
  

   owe 
  their 
  appearance 
  to 
  their 
  excessive 
  tenuity. 
  What 
  the 
  

   nature 
  of 
  these 
  minute 
  bodies 
  may 
  be 
  it 
  is 
  impossible 
  to 
  say, 
  

   since 
  they 
  exert 
  no 
  action 
  on 
  polarized 
  light. 
  The 
  most 
  natu- 
  

   ral 
  supposition 
  is 
  that 
  they 
  are 
  either 
  diopside 
  or 
  feldspar, 
  and 
  

   I 
  am 
  inclined 
  to 
  consider 
  them 
  the 
  latter, 
  — 
  probably 
  orthoclase, 
  

   — 
  basing 
  my 
  opinion 
  on 
  the 
  results 
  of 
  analysis 
  and 
  their 
  rather 
  

   remote 
  analogies 
  with 
  forms 
  seen 
  elsewhere. 
  Quite 
  well 
  

   developed 
  flow-structure 
  is 
  observed, 
  which 
  is 
  brought 
  out 
  

   more 
  prominently 
  by 
  the 
  presence 
  of 
  some 
  narrow 
  dusty 
  gray 
  

   streaks. 
  The 
  specific 
  gravity 
  was 
  found 
  to 
  be 
  2*601 
  at 
  18° 
  C, 
  

   the 
  lower 
  figure 
  as 
  compared 
  with 
  that 
  of 
  the 
  Mt. 
  Pagos 
  speci- 
  

   men 
  being 
  chiefly 
  due 
  to 
  the 
  more 
  highly 
  vitreous 
  character. 
  

  

  * 
  Rosenbuscb. 
  : 
  Mikr. 
  Phys., 
  ii, 
  890, 
  1896, 
  also 
  Taf. 
  v, 
  fig. 
  4. 
  

  

  