Granite of Aberdeenshire. 47 



both the felspar and quartz in a crystallized state, and very 

 nearly resembling in this respect many of the granites of 

 Bennachie, already mentioned, as well as some of those which 

 occur in Arran. The quartz, in particular, is remarkable for 

 bearing those characters which it so often presents in granite, 

 being brown, and often crystallized in its most ordinary form, 

 so as to attain an inch or more in length. It is remarkable 

 that the same circumstance occurs in the quartz belonging to 

 the granite of Arran, in a manner so exactly similar that the 

 specimens are undistinguishable. 



Among the varieties of trap occurring in Sky is found a com- 

 pound of hypersthene and felspar to which I have given the 

 name of hypersthene rock. In its external general forms, the 

 aspect of this rock is such as to be undistinguishable from that 

 of granite. Like this, it is found in huge curved beds, some- 

 times divided into prismatic and cuboidal forms, and risings 

 into those sharp and permanent peaked summits, which are 

 so often characteristic of granite, and which have indeed been 

 deemed peculiar to it. Although the mineral composition of 

 hypersthene rock is entirely different from that of any granite 

 yet known, the texture is the same ; and it is further highly 

 worthy of remark, that, in some places, it assumes the foliated 

 tendency of gneiss, from a peculiar parallel disposition of the 

 crystals of hypersthene. Further, in many parts, it contains 

 garnets, disposed in the same manner as they often are in 

 granite, and of the same character. 



That the ordinary greenstones of the trap family sometimes 

 resemble those similar compounds found in granite, by con- 

 taining quartz, is matter of such general notoriety that it is un- 

 necessary to describe the examples. Nor is mica necessarily ex- 

 cluded from these, although it must be considered as a rare 

 ingredient. With respect to the texture of the rock, or the 

 magnitude and disposition of the integrant minerals, it may be 

 observed, that the greenstones have a character which is often 

 perfectly granitic, the felspar and hornblende being distinctly 

 crystallized on a very large scale, and interfering with each 

 other's regular forms. The neighbourhood of Edinburgh pre- 



