Mineralogy of Sky, 69 



on the northern. It offers no remarkable variety of composition, 

 but appears to consist of various modifications of that syenite about 

 to be described, to which on a former occasion I proposed that the 

 name should be limited, the syenite connected with the trap for- 

 mation. Those who are acquainted with the syenite of Arran, of 

 which the main constituent is felspar, will recognize in this a similar 

 rock, of which examples may also be found in the neighbouring 

 island of Raasa, as well as in many other of the "Western islands. 

 The hill of Glamich may be selected as a specimen of those which are 

 formed of syenite and of clinkstone, both of which are in this case 

 strongly marked, since, as already mentioned, the former displays its 

 reddish yellow hue, and the latter a dark blue tint. In other respects 

 there is no difference between these rocks in the general disposition, 

 which is in both equally irregular and ill defined. I could not dis- 

 cover the contact of these substances, but am convinced from other 

 observations that they are connected by a common bond of tran- 

 sition or of position, and that they present no essential differences 

 in geological relations. As the syenite of this hill presents no 

 peculiar varieties, and as the clinkstone has been already described, 

 one common description of the former will serve for the whole 

 group. There is probably cause for me to regret that I could 

 procure no more extensive access to the hills of this group, 

 but the uninhabited and desart state of this tract of country renders 

 it nearly impossible, since the limits of the longest day are insuffi- 

 cient for their examination, and since the storms and rains of 

 this wild island form but a dreary canopy to its rocky pillow. 

 I can therefore add nothing more precise to the general idea I 

 have already given of the connection of the syenite with the trap 

 and with the clinkstone. The light coloured rocks which belong 

 to the group appear in all cases to consist of the several vari- 



