﻿HAUGHTON 
  GRANITES 
  OF 
  IRELAND. 
  

  

  277 
  

  

  § 
  III. 
  Comparison 
  of 
  the 
  Granites 
  of 
  Donegal 
  with 
  those 
  of 
  

   Scotland 
  and 
  Sweden. 
  

  

  The 
  granites 
  of 
  Scotland 
  and 
  Sweden 
  resemble 
  the 
  granites 
  of 
  

   Donegal 
  in 
  being 
  stratified 
  and 
  in 
  containing 
  the 
  same 
  constituent 
  

   minerals. 
  

  

  I 
  here 
  give 
  the 
  analyses 
  of 
  two 
  Scotch 
  granites, 
  for 
  the 
  oppor- 
  

   tunity 
  of 
  examining 
  which 
  I 
  am 
  indebted 
  to 
  the 
  courtesy 
  of 
  Sir 
  

   R 
  I. 
  Murchison, 
  K.C.B. 
  

  

  Table 
  VIII. 
  — 
  Analyses 
  of 
  Scotch 
  Granites. 
  

  

  No. 
  

  

  Locality. 
  

  

  c3 
  

  

  o3 
  

  

  a 
  

  

  1 
  

  

  3 
  

  

  i 
  — 
  i 
  

  

  ©' 
  

  

  c 
  o 
  

  

  o 
  *■< 
  

  

  1— 
  I 
  Oi 
  

  

  © 
  

   1—1 
  P-, 
  

  

  © 
  

  

  8 
  

  

  i-3 
  

  

  # 
  c3 
  

  

  00 
  

  

  OS 
  

  

  S3 
  

  

  O 
  

  

  02 
  

  

  CO 
  

   oj 
  

  

  O 
  

  

  On 
  

  

  © 
  

  

  03 
  O 
  

  

  © 
  

  

  S3 
  

  

  'c3 
  

  

  -4-3 
  

   O 
  

  

  1. 
  

   2. 
  

  

  Strontian 
  

  

  62-00 
  

   70-60 
  

  

  1760 
  

   16-40 
  

  

  4-78 
  

   1-52 
  

  

  0-74 
  

   0-36 
  

  

  4-95 
  

   2-47 
  

  

  3-17 
  

   1-00 
  

  

  4-08 
  

   414 
  

  

  325 
  

   4-29 
  

  

  0-40 
  

   0-48 
  

  

  

  100-97 
  

   100-26 
  

  

  Tobermurry, 
  ] 
  

  

  Mull 
  ...; 
  

  

  1. 
  Strontian. 
  — 
  This 
  granite 
  is 
  somewhat 
  like 
  the 
  Ardara 
  granite 
  in 
  appear- 
  

  

  ance, 
  and 
  also 
  like 
  the 
  black 
  gneissose 
  granite, 
  wliich 
  is 
  found 
  as 
  a 
  

   variety 
  at 
  Grlen, 
  in 
  the 
  co. 
  Donegal. 
  It 
  is 
  medium 
  grained. 
  It 
  

   contains 
  — 
  

  

  (a.) 
  Quartz. 
  

  

  (b.) 
  Felspar, 
  white 
  (oligoclase), 
  having 
  the 
  characteristic 
  strias. 
  

  

  (c.) 
  Black 
  mica, 
  abundant. 
  

  

  2. 
  Tobermurry, 
  Mull. 
  — 
  A 
  coarse-grained 
  granite, 
  resembling 
  the 
  coarser 
  va- 
  

  

  rieties 
  of 
  the 
  typical 
  granite 
  of 
  Donegal. 
  It 
  contains 
  — 
  

   (a.) 
  Quartz, 
  abundant. 
  

  

  (b.) 
  Pink 
  orthoclase, 
  large 
  crystals 
  (£ 
  in. 
  to 
  ^ 
  in.). 
  

   (<?.) 
  White 
  oligoclase, 
  striated. 
  

   (d.) 
  Black 
  mica, 
  not 
  abundant. 
  

   (e.) 
  Sphene-facets, 
  occasional. 
  

  

  It 
  remains 
  to 
  be 
  considered 
  how 
  far 
  the 
  analyses 
  of 
  the 
  Scotch 
  

   granites 
  admit 
  of 
  being 
  represented 
  by 
  a 
  mixture 
  of 
  quartz, 
  ortho- 
  

   clase, 
  oligoclase, 
  and 
  black 
  mica. 
  In 
  order 
  to 
  solve 
  this 
  question, 
  

   it 
  is 
  necessary 
  to 
  calculate 
  their 
  oxygen 
  -ratios, 
  and 
  apply 
  equa- 
  

   tions 
  (4) 
  to 
  them. 
  

  

  Table 
  IX. 
  — 
  Oxygen 
  

  

  in 
  Scotch 
  Granites. 
  

  

  

  

  Locality. 
  

  

  ei 
  

   _© 
  

  

  r— 
  1 
  

  

  0Q 
  

  

  03 
  

  

  3 
  

   3 
  

  

  © 
  

  

  C 
  O 
  

   H-f 
  Oh 
  

  

  Iron 
  and 
  

  

  Manganese, 
  

  

  protoxide. 
  

  

  © 
  

  

  .2 
  

  

  co 
  

  

  © 
  

   g 
  

  

  c3 
  

  

  03 
  

  

  T5 
  

   O 
  

   W 
  

  

  CO 
  

  

  03 
  

   O 
  

  

  Strontian 
  

   Tobermurry 
  ... 
  

  

  32-192 
  

   36-657 
  

  

  8-227 
  

   7-666 
  

  

  1-432 
  

   0455 
  

  

  0-253 
  

   0-186 
  

  

  1-407 
  

   0-702 
  

  

  1-239 
  

   0-427 
  

  

  1-047 
  

   1062 
  

  

  0-551 
  

  

  0-728 
  

  

  From 
  this 
  Table 
  the 
  following 
  is 
  deduced 
  

  

  