q 
468 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
as that described as constituting a large portion of Skye, as well as of Mull and 
St Kilda.” “This syenite also reposes immediately on the sandstone.” “ This 
syenite ought to be distinguished by an appropriate name, since the ingredient 
united to the felspar is augite and not hornblende.” “‘In the neighbourhood 
of Harris I obtained hypersthene, which in mineral character was not to be 
distinguished from the specimens described as existing in Skye; it occurs in 
compound veins traversing the augite rock. One variety of the rock has 
everywhere the aspect of rusty iron. It gives a singularly barren and desolate 
look to the part of Rum which it occupies, and in this respect and its russet 
hue strongly reminds the spectator of the naked and sterile appearance of Loch 
Scavig. This rock is remarkably sonorous when struck, rendering a sound 
precisely like that of iron.” “Under Scuirmore the sandstone beds are 
traversed in one place by a vein of the augite rock which forms a considerable 
portion of the island.” 
From Dr Maccuttocu’s description of his hypersthene rock of Skye, the 
following quotations are made :—“On the shore at the foot of Garsven the 
overlying position of the hypersthene to the red sandstone is distinctly visible. 
The strata of the latter are traversed by numerous veins of the former.” “A 
question will naturally arise here, namely, whether there is any difference 
between the several rocks of the unstratified division ; whether, for example, 
the syenite is of prior or posterior origin to the hypersthene rocks of the 
Cuchullins. If that which is just related respecting the interchanges of the 
two be correct, there is no reason to imagine any such differences to exist. 
Still, however, certain portions may be seen which appear posterior to the 
syenite.” “In some places large veins are seen composed of a very compact 
hard substance, as sonorous as cast iron; there occur, also, thin veins of a 
black substance rather resembling Lydian stone than any form of basalt.” “The 
large concretions of hypersthene are found in veins.” “In the simplest small- 
grained variety of the rock it cannot easily be distinguished from a common 
greenstone.” . 
The inference to be drawn from the above must be, that, if not one and the 
same, Maccuttocn’s “hypersthene rock” of the Cuchullins and his “augite 
rock” of Rum are but slightly varying modifications of one and the same, and 
that the rock is igneous. 
Both rest upon his “syenite,” which in both islands rests upon red sand- 
stone. According to him, both alike pass by insensible gradations into that 
syenite, as they also do into a great many other varieties of igneous rock. 
When fine-grained, neither can be distinguished from greenstone. Both carry 
veins resembling “ Lydian stone,” and of a coarse-grained variety which con- 
tains MaccuLLocnu’s “ hypersthene.” 
It is necessary here to make another quotation from Maccuttocn. He 

