﻿^ 
  r 
  °l* 
  53*] 
  0If 
  KOCKS 
  FROM 
  THE 
  BALUCHISTAN 
  BORDER. 
  303 
  

  

  some 
  of 
  them 
  intensely 
  so. 
  In 
  No. 
  1418 
  the 
  interstitial 
  portions 
  

   have 
  to 
  some 
  extent 
  been 
  converted 
  into 
  a 
  serpentinous 
  product, 
  

   and 
  in 
  others 
  epidote 
  and 
  calcite 
  have 
  been 
  found 
  as 
  secondary 
  

   products. 
  

  

  No. 
  1427 
  was 
  difficult 
  to 
  interpret, 
  as 
  the 
  fragments 
  were 
  all 
  of 
  

   very 
  much 
  the 
  same 
  kind 
  of 
  lava; 
  but 
  on 
  having 
  a 
  thicker 
  slice 
  

   made, 
  and 
  after 
  digestion 
  in 
  hot 
  hydrochloric 
  acid, 
  the 
  distinction 
  

   between 
  the 
  different 
  lavas 
  could 
  be 
  well 
  seen, 
  and 
  the 
  fragmentary 
  

   character 
  of 
  the 
  rock 
  came 
  out 
  clearly. 
  

  

  Among 
  the 
  lapilli 
  are 
  fragments 
  of 
  a 
  dark 
  basic 
  lava, 
  but 
  I 
  have 
  

   not 
  observed 
  any 
  of 
  olivine-basalt. 
  

  

  No. 
  1465, 
  from 
  the 
  natural 
  monolith 
  of 
  Neza-i-Sultan, 
  is 
  a 
  fine 
  

   ash 
  made 
  up 
  of 
  fragments 
  of 
  trachyte-looking 
  andesites, 
  so 
  like 
  each 
  

   other 
  that 
  it 
  is 
  difficult 
  to 
  distinguish 
  the 
  ash 
  from 
  a 
  lava. 
  

  

  Holocrystalline 
  Rocks. 
  

  

  No. 
  1462. 
  Biotite-hornblende-granite. 
  

  

  The 
  hill 
  at 
  Bharab 
  Chah 
  previously 
  mentioned 
  (p. 
  301) 
  is 
  com- 
  

   posed 
  of 
  this 
  granite. 
  The 
  slice 
  taken 
  from 
  my 
  hand-specimen 
  

   contains 
  orthoclase, 
  oligoclase, 
  quartz, 
  apatite, 
  biotite, 
  and 
  a 
  little 
  

   hornblende, 
  zircon, 
  and 
  sphene. 
  

  

  The 
  hornblende 
  is 
  brown-green 
  in 
  transmitted 
  light. 
  It 
  is 
  not 
  

   by 
  any 
  means 
  as 
  plentiful 
  as 
  the 
  biotite, 
  which 
  is 
  a 
  good 
  deal 
  

   decomposed 
  and 
  here 
  and 
  there 
  altered 
  into 
  chlorite. 
  Apatite 
  is 
  

   rather 
  abundant. 
  The 
  quartz 
  deeply 
  corrodes 
  the 
  felspars, 
  horn- 
  

   blendes, 
  and 
  micas. 
  (See 
  PI. 
  XX, 
  figs. 
  5 
  & 
  6.) 
  

  

  The 
  solvent 
  action 
  of 
  the 
  acid 
  matrix 
  on 
  the 
  more 
  basic 
  materials 
  

   that 
  had 
  previously 
  crystallized 
  out 
  seems 
  to 
  be 
  a 
  rather 
  frequent 
  

   feature 
  in 
  granites, 
  and 
  it 
  appears 
  to 
  mark 
  that 
  stage 
  in 
  the 
  history 
  

   of 
  the 
  rock 
  when 
  the 
  granite, 
  full 
  of 
  crystals 
  formed 
  under 
  plutonic 
  

   conditions, 
  was 
  moved 
  upwards 
  into 
  place, 
  and 
  partial 
  re-solution 
  

   commenced 
  from 
  relief 
  of 
  pressure 
  and 
  consequent 
  lowering 
  of 
  the 
  

   point 
  of 
  fusion 
  and 
  from 
  other 
  causes. 
  The 
  corrosion 
  of 
  phenocrysts 
  

   by 
  the 
  matrix 
  in 
  the 
  case 
  of 
  quartz-porphyries 
  has 
  been 
  often 
  

   described 
  ; 
  but 
  in 
  the 
  case 
  of 
  granites 
  this 
  partial 
  re-solution 
  of 
  the 
  

   first-formed 
  minerals 
  does 
  not 
  appear 
  to 
  have 
  been 
  noticed 
  by 
  

   previous 
  observers. 
  

  

  Liquid 
  inclusions 
  are 
  common 
  in 
  the 
  quartz, 
  but 
  no 
  moving 
  bubbles 
  

   of 
  any 
  size 
  are 
  to 
  be 
  seen. 
  

  

  No. 
  1421. 
  Quartz-syenite. 
  Sp. 
  gr. 
  = 
  2*750. 
  

  

  From 
  the 
  west 
  side 
  of 
  the 
  great 
  fault 
  at 
  Chili 
  Katch 
  in 
  the 
  Sarlat 
  

   Range. 
  

  

  The 
  hand-specimen 
  exhibits 
  a 
  somewhat 
  obscure 
  parallelism 
  of 
  

   structure 
  which 
  is 
  not 
  noticeable 
  under 
  the 
  microscope. 
  The 
  slice 
  

   contains 
  oligoclase, 
  orthoclase, 
  quartz, 
  hornblende, 
  biotite, 
  apatite, 
  

   sphene, 
  and 
  magnetite, 
  with 
  some 
  epidote, 
  calcite, 
  and 
  chlorite, 
  as 
  

   secondary 
  products 
  of 
  decomposition. 
  

  

  