﻿212 
  Drs. 
  Smeeth 
  and 
  Watson 
  on 
  the 
  Radioactivity 
  of 
  

  

  which 
  carry 
  it, 
  is 
  subject 
  to 
  magmatic 
  segregation. 
  The 
  

   amount 
  of 
  radium 
  in 
  the 
  segregated 
  portions 
  of 
  a 
  magma 
  

   sometimes 
  increases 
  and 
  sometimes 
  decreases 
  with 
  increase 
  

   of 
  basicity. 
  

  

  5. 
  Amongst 
  magmas, 
  the 
  more 
  basic 
  appear 
  to 
  be 
  lower 
  in 
  

   radium 
  than 
  the 
  more 
  acid, 
  and, 
  in 
  the 
  products 
  of 
  granitic 
  

   magmas, 
  the 
  pegmatites 
  appear 
  to 
  carry 
  more 
  radium 
  than 
  

   the 
  corresponding 
  granites. 
  The 
  Charnockite 
  magma, 
  which 
  

   was 
  probably 
  of 
  intermediate 
  composition, 
  forms 
  a 
  striking 
  

   exception, 
  and 
  is 
  notable 
  for 
  its 
  extremely 
  low 
  radioactivity. 
  

  

  6. 
  In 
  the 
  case 
  of 
  rocks 
  of 
  somewhat 
  similar 
  character 
  and 
  

   composition, 
  and 
  in 
  which 
  other 
  means 
  of 
  distinction 
  or 
  

   identification 
  are 
  lacking, 
  a 
  marked 
  difference 
  in 
  the 
  radium 
  

   contents 
  may 
  afford 
  a 
  means 
  of 
  correlating 
  them 
  with 
  known 
  

   groups 
  or 
  formations 
  for 
  which 
  the 
  radium 
  limits 
  have 
  been 
  

   sufficiently 
  determined. 
  

  

  Bangalore, 
  March 
  1917. 
  

  

  Table 
  I. 
  

  

  Radioactivity 
  of 
  Rocks 
  from 
  the 
  Mysore 
  State. 
  

   (The 
  rock 
  groups 
  are 
  arranged 
  in 
  order 
  of 
  age 
  from 
  the 
  oldest 
  

   to 
  the 
  youngest. 
  The 
  radium 
  is 
  given 
  in 
  units 
  of 
  10 
  ~ 
  12 
  gramme 
  

   per 
  gramme 
  of 
  rock.) 
  

  

  Serial 
  

   No. 
  

  

  Eegistered 
  

  

  No. 
  

  

  Description. 
  

  

  Eadium. 
  

  

  Remarks. 
  

  

  Group 
  1. 
  Dharvvar 
  System 
  — 
  Lower 
  (hornblendic) 
  series. 
  

  

  1. 
  

  

  

  i't. 
  

   Balaghat 
  Mine 
  — 
  depth 
  1000 
  

  

  021 
  

  

  (The 
  first 
  15 
  samples 
  are 
  

  

  2. 
  

  

  

  „ 
  2000 
  

  

  014 
  

  

  all 
  hornblende 
  schists 
  

  

  3. 
  

  

  

  „ 
  3000 
  

  

  0-21 
  

  

  and 
  epidiorites 
  from 
  the 
  

  

  4. 
  

  

  

  Nundvdroog 
  Mine 
  ,, 
  1000 
  

  

  017 
  

  

  Kolar 
  Gold 
  Field. 
  Th^ 
  

  

  5. 
  

  

  

  „ 
  3000 
  

  

  014 
  

  

  depths 
  are 
  measured 
  on 
  

  

  6. 
  

  

  

  Ooreguui 
  Mine 
  ,, 
  1000 
  

  

  018 
  

  

  the 
  dip 
  of 
  the 
  lode 
  .) 
  

  

  7. 
  

  

  

  „ 
  2000 
  

  

  0-17 
  

  

  

  8. 
  

  

  

  „ 
  4000 
  

  

  021 
  

  

  

  9. 
  

  

  

  Champion 
  Reef 
  Mine 
  „ 
  2000 
  

  

  0-24 
  

  

  

  10. 
  

  

  

  „ 
  „ 
  3000 
  

  

  0-18 
  

  

  

  11. 
  

  

  

  „ 
  „ 
  4000 
  

  

  0-14 
  

  

  

  12. 
  

  

  

  Mysore 
  Mine 
  „ 
  1000 
  

  

  034 
  

  

  Altered 
  schist. 
  

  

  13. 
  

  

  

  „ 
  2000 
  

  

  0-21 
  

  

  

  14. 
  

  

  

  „ 
  3000 
  

  

  023 
  

  

  

  15. 
  

  

  

  „ 
  4000 
  

  

  096 
  

  

  Much 
  altered 
  schist, 
  part 
  

   of 
  the 
  lode 
  formation; 
  

   contact 
  alteration 
  close 
  

   to 
  quartz 
  of 
  lode. 
  

  

  16. 
  

  

  S2/377 
  

  

  Amphibolite, 
  footwall 
  of 
  lode, 
  

  

  Ooregum. 
  

   Fine 
  hornblende 
  schist, 
  Baba- 
  

  

  0-82 
  

  

  Contact 
  alteration. 
  

  

  17. 
  

  

  Z3/510 
  

  

  0-25 
  

  

  

  

  

  budan 
  Hills, 
  Kadur 
  District 
  

  

  

  < 
  

  

  18. 
  

  

  Jl/535 
  

  

  Hornblende 
  granulite 
  ; 
  Kolar 
  

   schists. 
  

  

  019 
  

  

  

  