﻿412 
  N. 
  STORY-MASKELYNE 
  AND 
  W. 
  FLIGHT 
  ON 
  THE 
  CHARACTER 
  

  

  "With 
  the 
  exception 
  of 
  the 
  enstatite 
  of 
  Aloysthal, 
  in 
  Moravia, 
  

   analyzed 
  by 
  Von 
  Hauer, 
  this 
  bronzite 
  is 
  distinguished 
  for 
  containing 
  

   less 
  iron 
  oxide 
  than 
  any 
  specimen 
  as 
  yet 
  examined. 
  

  

  Although 
  the 
  mineral 
  was 
  dried 
  at 
  120° 
  C, 
  a 
  little 
  water 
  was 
  still 
  

   retained 
  ; 
  but 
  its 
  amount 
  was 
  not 
  determined. 
  

  

  A 
  portion 
  of 
  the 
  powdered 
  mineral 
  was 
  treated 
  with 
  a 
  mixture 
  of 
  

   equal 
  volumes 
  of 
  strong 
  hydrochloric 
  acid 
  and 
  water 
  at 
  100° 
  C. 
  during 
  

   twenty 
  hours, 
  and 
  subsequently 
  with 
  potash. 
  Rather 
  more 
  than 
  a 
  

   quarter 
  of 
  the 
  material 
  was 
  dissolved, 
  as 
  shown 
  below 
  : 
  — 
  

  

  Oxygen 
  Ratios. 
  

  

  Silicic 
  acid. 
  15-445 
  8-23 
  

  

  Alumina 
  0-648 
  

  

  Iron 
  oxide, 
  with 
  a 
  trace 
  of 
  

  

  chromium 
  oxide 
  ... 
  . 
  1-505 
  0-33 
  "1 
  q 
  ftfl 
  

   Magnesia 
  8-685 
  3-47 
  J 
  ^ 
  8U 
  

  

  26-283 
  

   The 
  action 
  of 
  the 
  acid, 
  therefore, 
  was 
  that 
  of 
  a 
  solvent 
  only. 
  

  

  3. 
  Smaragdite. 
  

  

  Brilliant 
  greyish-green 
  fragments 
  of 
  crystals 
  are 
  met 
  with 
  among 
  

   the 
  minerals 
  in 
  the 
  rock 
  of 
  Du 
  Toit's 
  Pan. 
  They 
  consist 
  chiefly 
  of 
  the 
  

   planes 
  of 
  a 
  prism 
  with 
  the 
  angle, 
  as 
  determined 
  by 
  the 
  goniometer, 
  of 
  

   about 
  123° 
  15', 
  which 
  is 
  that 
  of 
  a 
  mineral 
  of 
  the 
  hornblende 
  type. 
  

  

  Acid 
  had 
  no 
  action 
  upon 
  this 
  mineral 
  beyond 
  removing 
  the 
  

   adhering 
  carbonate. 
  After 
  having 
  been 
  dried 
  for 
  several 
  hours 
  at 
  

   120° 
  C, 
  it 
  was 
  analyzed 
  with 
  the 
  following 
  result 
  : 
  — 
  

  

  Oxygen 
  Ratios. 
  

  

  Silicic 
  acid 
  52-967 
  28-25 
  

  

  Alumina, 
  with 
  a 
  little 
  chromium 
  oxide 
  1 
  -939 
  

  

  Iron 
  protoxide 
  4-522 
  1-005 
  1 
  

  

  Lime 
  20-475 
  5-85 
  L 
  13-85 
  

  

  Magnesia 
  17-487 
  6-995 
  J 
  

  

  Soda, 
  with 
  trace 
  of 
  potash 
  1*772 
  

  

  Water 
  0577 
  

  

  99-739 
  

  

  III. 
  ROCK-SPECIMENS 
  FROM 
  New 
  RUSH, 
  OR 
  CoLESBERG 
  KOPJE. 
  

  

  The 
  aspect 
  of 
  the 
  rocks 
  from 
  New 
  Rush 
  appears 
  to 
  vary 
  consider- 
  

   ably 
  with 
  the 
  depth. 
  In 
  the 
  higher 
  parts 
  and 
  down 
  to 
  70 
  or 
  80 
  

   feet 
  the 
  prevailing 
  tint 
  is 
  a 
  drab 
  yellow 
  ; 
  at 
  greater 
  depths 
  it 
  as- 
  

   sumes 
  a 
  bluer 
  tint, 
  and 
  consists 
  largely 
  of 
  a 
  breccia 
  containing 
  frag- 
  

   ments 
  of 
  the 
  shales 
  through 
  which 
  the 
  rock 
  has 
  been 
  intruded, 
  with 
  

   occasional 
  fragments 
  of 
  igneous 
  rocks. 
  

  

  In 
  selecting 
  material 
  for 
  the 
  investigation 
  of 
  this 
  much 
  metamor- 
  

   phosed 
  rock, 
  those 
  varieties 
  were 
  taken 
  in 
  which 
  the 
  metamorphosis 
  

   appears 
  to 
  be 
  the 
  least 
  complete, 
  while 
  they 
  still 
  retained 
  charac- 
  

   teristic 
  features 
  of 
  the 
  diamantiferous 
  deposit. 
  

  

  