244 B. KOTÖ. 



uniform. As a general rule they are in fine crystals. The .same 

 glohular interpositions, already spoken of, make their appearance in 

 these feldspars as in those of the intruding rock, and the (piartz ])ene- 

 trates into the suhstance of the feldspars, just like the pockets in the 

 quartz of (piartz-})orphyries. The liornblende forms the most im- 

 portant of all the components not only in respect of its quantity, but 

 of its very occurrence in the rock ; while in the enclosing granite we 

 fail to find even a trace of this mineral. 



Tliis f ict affords us a clue to the two granites being of totally 

 diflferent origin, and by no means mere bands, such as might arise 

 from local differentiation and partial movement of a granitic magma. 

 Moreover, the ano'ular and broken outlines of fras^ments of the rock 

 speak for the foreign origin of the hornblende-granite ; and the pre- 

 sence of the amphibole in this and the absence in the other give con- 

 clusive evidence as to the really fragmentary nature of the older granite 

 caught up by the younger one. 



The hornblende is dark bottle-green, and non-pleochroic, or, if 

 at all, very weakly so. It is destitute of its own form, its apparently 

 regular outline being due to the mutual dispositions of the neighbour- 

 ing quartzes and feldspars. The mica is comparatively idiomorphic 

 with respect to its closely associated hornblende, and grows round the 

 hornblende in clusters. The biotite is often enclosed in the hornblende, 

 consequently some of it must l)e younger than the mica. It is high- 

 ly probable that the imperfect ness of the shape of the hornblende is due 

 to its simultaneous formation with the feldspars. The quartz is com- 

 paratively rare, and contains abundant li(|uid-inclusions. Titanite in 

 the form of o;rains is also found which is wantino- in tlie biotite-ofra- 

 nite. Ijlack iron-glance, reflecting somewhat bluish rays, is plentiful ; 

 some yellow pyrites is present. These iron ores have hitherto not 

 been discerned in the biotite -granite itself. 



