1870.] Rev. Samuel Haughton on the Granites of Scotland. 313 



No. 4. Callernish, extreme west of Lewis. In metamorplric Granite; 

 in large grey crystals, with a slight shade of pink, translucent. 

 The oxygen ratio of these felspars is as follows : — 



No. 1. No. 2. No. 3. No. 4. 



Silica 33*95G 33*45G 33*4/8 33*477 



Alumina &c. .. 8*898 8*950 9*348 9*348 



Lime 0*0G1 0-187 0-28G 0-221 



Soda 0-929 0*699 0*440 0-561 



Potash 1*908 2*059 2*171 2*051 



45752 45*351 45*723 45*G58 



From this Table we find the oxygen ratios : — 



No. 1. No. 2. No. 3. No. 4. 



Silica 11*37 11*35 11-55 11-82 



Peroxides 3*06 3*04 3*22 3-30 



Protoxides .... 1*00 1-00 1*00 1*00 



The Granites of central and western Scotland are metamorphic rocks, 

 like those of Donegal and Norway, with which they are geologically iden- 

 tical; and truly eruptive Granite occurs at only a few localities, as, for 

 example, near Peterhead. 



The second felspar associated with Orthoclase in the Metamorphic 

 Granites is Oligoclase, as in Donegal ; while the second felspar associated 

 with Orthoclase in the eruptive Granites is Albite, as in Mourne, Leinster, 

 and Cornwall. The fact thus indicated by the Scotch Granites is com- 

 pletely in accordance w r ith the mode of occurrence of Oligoclase and 

 Albite in the Irish Granites. 



II. Oligoclase. 



No. 1. No. 2. 



Silica 62-00 61-88 



Alumina 23*20 24-80 



Magnesia Trace. 



Lime 4-71 4*93 



Soda 9*20 8*12 



Potash 0-43 0*98 



99*54 100-71 



No. 1. This Oligoclase occurs in the Granite of Craigie-Buckler, near 

 Aberdeen ; it is white and opaque, and so much resembles Cleavelandite in 

 appearance as to have been mistaken for that variety of Albite ; its analysis 

 proves it to be Oligoclase. The crystals do not exhibit striation. 



No. 2. From the Granite of Rhiconicb, in the west of Sutherlandshire ; 



2 b 2 



