various parts of Scotland. 407 



improbable but that plasma as well as heliotrope may be an inmate 

 of the trap rocks of Scuir-more. 



A substance is occasionally brought from India, known to lapi-* 

 daries by the name of brown carnelian, and it is esteemed peculiarly 

 rare. This substance also is found among the chalcedonies of Rum, 

 occupying the same situation as the green varieties, and differing 

 from them only in colour. It probably owes its stain to iron. 

 Motley mixtures of brown, and green, of considerable beauty, add 

 to the variety of ornamental stones which these rocks contain. 



The apparently inaccessible nature of the southern shore of Rum, 

 prevented me from extending further my observations on this 

 interesting island. But in coasting it slowly along, it offered the 

 same general appearance as the cliffs I have now been describing 

 which look toward the island of Canna, exhibiting one formidable 

 wall of basaltic aspect, reposing on a base of sandstone. It will be 

 for more successful geologists to examine whether circumstances 

 equally interesting, and of a different nature, may not be found 

 among the caverns and ruins of this repulsive, if not absolutely 

 inaccessible coast. 



I have little to add to the description of Egg given In the 

 " Mineralogy of the Scottish isles," but the following fact relating 

 to the situation of the promontory called the Scuir of Egg, which 

 is not noticed in that work. The columns which form this most 

 magnificent precipice, exceeding in grandeur and picturesque effect 

 even the far famed Staffa, are of a black pitchstone porphyry. 

 They are disposed in various perpendicular, inclined, and horizontal 

 directions, and are either straight, or curved, but never jointed. 

 The felspar which they contain is the glassy variety. The lines 



