﻿CHARNWOOD-FOREST 
  ROCKS. 
  197 
  

  

  19. 
  Analyses 
  of 
  five 
  Rocks 
  from 
  the 
  Charnwood-Eorest 
  District. 
  

   By 
  E. 
  E. 
  Berry, 
  Esq. 
  Communicated, 
  with 
  Notes, 
  by 
  Prof. 
  

   T. 
  G. 
  Bonney, 
  M.A., 
  E.R.S., 
  Sec.G.S. 
  (Read 
  December 
  21, 
  

  

  1881.) 
  

  

  The 
  following 
  analyses, 
  undertaken 
  by 
  the 
  author 
  at 
  the 
  request 
  of 
  

   Prof. 
  Bonney, 
  may 
  have, 
  it 
  is 
  hoped, 
  an 
  interest 
  not 
  only 
  of 
  them- 
  

   selves, 
  but 
  also 
  when 
  viewed 
  in 
  connexion 
  with 
  the 
  remarks 
  pre- 
  

   viously 
  made 
  upon 
  the 
  rocks 
  by 
  Messrs. 
  Hill 
  and 
  Bonney 
  in 
  com- 
  

   munications 
  already 
  presented 
  to 
  the 
  Society 
  : 
  — 
  

  

  (1) 
  Homblendic 
  Granite 
  of 
  Mount 
  Sorrel. 
  

   Si0 
  2 
  69-94 
  

  

  Fe 
  A*l 
  lor 
  r 
  io-82 
  

  

  AlAfj 
  19 
  ' 
  8 
  ' 
  { 
  9-05 
  

  

  MnO 
  . 
  trace. 
  

  

  CaO 
  3-21 
  

  

  MgO 
  1-38 
  

  

  K,0 
  3-82 
  

  

  Xa.,0 
  1-32 
  

  

  H 
  2 
  1-30 
  

  

  Total 
  100-84 
  

  

  (2) 
  Syenite 
  from 
  Marhfield. 
  

  

  Si0 
  2 
  56-78 
  

  

  Fe 
  o 
  3 
  | 
  9ft 
  .o 
  r 
  . 
  f 
  18-81 
  

  

  AlX 
  j 
  28 
  ' 
  30 
  { 
  9-49 
  

  

  MnO 
  trace. 
  

  

  CaO 
  6-94 
  

  

  MgO 
  2-71 
  

  

  K 
  o 
  2-42 
  

  

  ffa.,0 
  2-73 
  

  

  H 
  2 
  1-10 
  

  

  Total 
  100-98 
  

  

  This 
  rock 
  may 
  be 
  taken 
  as 
  a 
  typical 
  example 
  of 
  the 
  coarser 
  

   variety 
  of 
  the 
  southern 
  syenites. 
  The 
  analysis 
  confirms 
  our 
  remark, 
  

   that 
  they 
  are 
  " 
  somewhat 
  intermediate 
  between 
  typical 
  quartz- 
  

   syenites 
  and 
  quartz-diorites." 
  The 
  percentage 
  of 
  silica, 
  however, 
  is 
  

   very 
  slightly 
  lower 
  than 
  we 
  should 
  have 
  anticipated 
  from 
  our 
  micro- 
  

   scopic 
  examination. 
  (T. 
  G. 
  B.) 
  

  

  * 
  The 
  iron 
  in 
  all 
  these 
  rocks 
  has 
  been 
  estimated 
  as 
  ferric 
  oxide. 
  

  

  t 
  This 
  rock, 
  as 
  well 
  as 
  the 
  Syenite 
  from 
  Markfield 
  (No. 
  2) 
  and 
  the 
  " 
  porphy- 
  

   roid 
  " 
  of 
  Sharpley 
  (No. 
  5), 
  contains 
  a 
  small 
  quantity 
  of 
  phosphoric 
  acid, 
  which 
  

   has 
  not 
  been 
  estimated 
  or 
  separated 
  from 
  the 
  alumina. 
  

  

  