﻿Vol. 
  53.] 
  ON 
  ROCKS 
  PROM 
  THE 
  BALUCHISTAN 
  BORDER. 
  305 
  

  

  The 
  rock 
  contains 
  countless 
  vein-like 
  cracks, 
  which 
  are 
  wide 
  at 
  

   one 
  end 
  and 
  branch 
  out 
  freely 
  until 
  they 
  dwindle 
  down 
  into 
  

   channels 
  of 
  hair-like 
  fineness 
  and 
  disappear. 
  These 
  cracks 
  ana- 
  

   stomose, 
  bifurcate, 
  cross 
  each 
  other 
  at 
  various 
  angles, 
  and 
  sometimes 
  

   disappear 
  to 
  reappear 
  farther 
  on, 
  They 
  are 
  all 
  filled 
  with 
  calcite. 
  

   In 
  some 
  of 
  the 
  hand-specimens 
  not 
  sliced, 
  and 
  not 
  enumerated 
  above, 
  

   the 
  calcite 
  in 
  quantity 
  at 
  least 
  equals 
  the 
  silt 
  with 
  which 
  it 
  

   appears 
  to 
  be 
  inextricably 
  mixed 
  up. 
  

  

  One 
  of 
  the 
  sub-rounded 
  grains 
  of 
  opal 
  is 
  traversed 
  by 
  two 
  

   calcite-filled 
  cracks, 
  whence 
  it 
  would 
  appear 
  that 
  the 
  rounded 
  

   bodies 
  composed 
  of 
  calcite 
  and 
  opal 
  were 
  original 
  components 
  of 
  the 
  

   silt, 
  and 
  were 
  not 
  introduced 
  by 
  infiltration 
  when 
  the 
  calcite-veins 
  

   were 
  formed. 
  

  

  The 
  silty 
  part 
  of 
  the 
  rock, 
  from 
  its 
  appearance 
  under 
  the 
  micro- 
  

   scope, 
  I 
  should 
  say 
  was 
  probably 
  formed 
  in 
  the 
  sea 
  at 
  or 
  near 
  the 
  

   foot 
  of 
  a 
  coral 
  reef. 
  Whether 
  the 
  cracking 
  was 
  caused 
  by 
  shrinkage 
  

   on 
  consolidation, 
  or 
  whether 
  the 
  rock 
  is 
  a 
  fault-breccia, 
  cannot 
  be 
  

   determined 
  from 
  the 
  examination 
  of 
  hand-specimens 
  alone. 
  

  

  In 
  conclusion, 
  I 
  proceed 
  to 
  enumerate 
  briefly 
  various 
  rocks 
  and 
  

   ores 
  given 
  to 
  me 
  for 
  determination. 
  The 
  most 
  convenient 
  plan 
  will, 
  

   I 
  think, 
  be 
  to 
  group 
  them 
  under 
  the 
  localities 
  in 
  which 
  they 
  were 
  

   found. 
  

  

  Saindak 
  Mountains. 
  

  

  (1) 
  Galena, 
  or 
  sulphide 
  of 
  lead. 
  This 
  appears 
  to 
  be 
  fairly 
  pure. 
  

  

  (2) 
  Silicate 
  of 
  copper 
  (chrysocolla). 
  

  

  (3) 
  Calcareous 
  epidote-rock. 
  It 
  is 
  composed 
  principally 
  of 
  epi- 
  

  

  dote, 
  calcite, 
  and 
  iron. 
  It 
  is 
  probably 
  the 
  product 
  of 
  the 
  

   alteration 
  of 
  a 
  volcanic 
  or 
  igneous 
  rock. 
  

  

  (4) 
  Reddle, 
  or 
  earthy 
  hydrated 
  ferric 
  oxide, 
  containing 
  numerous 
  

  

  crystals 
  of 
  selenite, 
  lumps 
  of 
  gypsum, 
  and 
  small 
  crystals 
  of 
  

   anthophvllite. 
  

  

  (5) 
  Sand. 
  This 
  fine-grained, 
  somewhat 
  earthy-looking 
  sand 
  was 
  

  

  found, 
  on 
  examination 
  under 
  the 
  microscope, 
  supplemented 
  

   by 
  some 
  chemical 
  tests, 
  to 
  be 
  composed 
  of 
  minute 
  frag- 
  

   ments 
  of 
  the 
  following 
  minerals 
  and 
  rocks 
  : 
  — 
  quartz, 
  calcite, 
  

   dolomite, 
  carbonate 
  of 
  iron, 
  garnet, 
  tourmaline, 
  muscovite, 
  a 
  

   reddish-brown 
  mica, 
  orthoclase- 
  and 
  plagioclase-felspars, 
  and 
  

   fragments 
  of 
  siliceous 
  rocks. 
  The 
  calcite 
  and 
  dolomite 
  w 
  r 
  ere 
  

   probably 
  derived 
  from 
  limestone 
  and 
  magnesian-limestone 
  

   rocks, 
  near 
  at 
  hand. 
  

  

  Koh-i- 
  Sultan. 
  

  

  (1) 
  Yellow 
  ochre, 
  used 
  by 
  the 
  natives 
  as 
  a 
  dye. 
  This 
  rock 
  is 
  

  

  composed 
  of 
  limonite, 
  with 
  some 
  sulphide 
  of 
  iron 
  and 
  a 
  good 
  

   deal 
  of 
  silica 
  as 
  impurities. 
  

  

  (2) 
  Red 
  ochre. 
  The 
  red 
  ochre 
  contains 
  many 
  crystals 
  of 
  gypsum 
  

  

  and 
  numerous 
  minute 
  crystals 
  of 
  anthophyllite. 
  

  

  (3) 
  Sulphur, 
  with 
  some 
  yellow 
  limonite 
  as 
  an 
  impurity. 
  

   Q. 
  J. 
  G. 
  S. 
  No. 
  211. 
  y 
  

  

  