on the Mountain Cruachan. 1 27 



nltes of which this mineral forms an ingredient. More often how- 

 ever their shape is perfectly defined, and they appear to be laminar 

 of which the edges are truncated or broken at angles with the plane. 

 In some places this appearance of fracture is so precise, that when 

 two fragments occur together in the granite the imagination as 

 easily replaces the separated parts as it does in the brecciated mar- 

 bles or agates : nay, further, the fragment will sometimes be 

 found to consist of an argillaceous or slightly micaceous schistus, 

 maintaining this character with scarcely a perceptible alteration 

 and sometimes only approaching to hornblende schist at its exte- 

 rior parts. It is also worthy of remark that these fragments some- 

 times exhibit at their edges stripes of different colours and degrees 

 of hardness, arising from the varying texture of the laminae which 

 compose them. The masses vary in size from an inch to a foot 

 and upwards, but whatever their size may be they have almost in- 

 variably parallel sides. The examples of this appearance are very 

 numerous both at Balahulish and in the rolled fragments of granite 

 which are spread over the Black mount to the eastward of Glenco, 

 and we shall presently see that the same granite with similar con- 

 nections occupies a very large tract of country. The frequency 

 of the occurrence also enables an observer to examine the specimens, 

 without difficulty, and to compare their various aspects and circum- 

 stances. From these I have no scruple in saying, that the granite, 

 now described contains fragments of schist imbedded in its mass, 

 generally so altered in their original appearance by their connection 

 with the granite, as to approach to, or partially to assume the 

 character of hornblende slate, but often also possessing the characters 

 of micaceous schist unchanged, and under all the varieties of aspect 

 by which it is characterizedjn the surrounding country. 



R 2 



