626 



SCOTLAND. 



Statistics. It remains to notice the trap and porphyry of Scot- 



^**^f*t*J land. 



Geology. The greatest mass of porphyry is that which lies in the 

 neighbourhood of Inverary, occupying a scattered but 



Porphyry, considerable space; and next to that is the mass which 

 occurs in Glenco, well known, a dependency of which 

 may be conceived to form the summit of Ben Nevis. 

 We know of no other extensive masses which appear 

 of equal antiquity, and the veins are far too numerous 

 and scattered to admit of description. All the other 

 porphyries we must rank with the later trap rocks. 



I rap. Qf tnesej Shetland possesses one portion in the island 



of Papa Stour ; but the Western islands display a great 

 extent of the rocks of this class. St. Kilda is thus 

 formed of augitic greenstone and syenite. Sky is en- 

 tirely formed of the same rocks, with the exception of 

 the south-eastern quarter, and of another small portion 

 at Strathaird. Here there are all the varieties of this 

 family, and among the rest, that rare substance hypers- 

 thene rock, already mentioned. As dependant on Sky, 

 we may name Ilasay, partly formed of porphyry, the 

 Shiant isles, Canna, Egg, Rum, and Muck. Egg also 

 contains pitchstone; and its celebrated Scuir was for- 

 merly noticed. 



Mull is the next great trap district in the islands, 

 being almost entirely formed of it, and including the 

 adjoining islands, excepting Inch Kenneth, of which 

 Staflfa is especially noted. To the south, Kerrera is 

 also chiefly formed of trap, with part of Seil ; but af- 

 ter this we meet with nothing further than veins, till 

 we arrive at Arran, about one half of which consists 

 of the rocks of this class. In the Clyde, Ailsa, the 

 smaller Cumbray, and the southern point of Bute, are 

 of the same materials. 



In the Highlands, the chief trap district is Airdna- 

 murchan towards the west, and Morven similarly, both 

 of them in this sense dependencies on Mull, The mi- 

 i^uter portions occurring on the borders of the High- 

 land mountains, can only be mentioned thus slightly. 

 But to the south of these, in the middle district, the 

 great range of the Sidlaw displays many insulated por- 

 tions of it, as does this country generally; the mass be- 

 coming more continuous near Perth, to be renewed in 

 the Ochil, and again in the Campsie Hills, till it meets 

 the Highland mountains. The northern shores of Fife 

 display a smaller range ; and through this whole cunty 

 even to Stirling, a crowd of summits and fragments im- 

 possible to specify, bespeak the once greater continuity 

 of an extensive central tract of this rock. Thus also, 

 North Berwick Law, Inchkeith, Arthur's Seat, the Pent- 

 land, and many more summits which need not be 

 named, indicate the former wider connections and extent 

 of a mass once lying over the coal field here, and reach- 

 ing to the westward till it is renewed in a more con- 

 tinuous manner to the west of Glasgow and the con- 

 fines of Ayr. 



Such is a sketch of the positions of a rock, which 

 nothing but a detailed and coloured map could render 

 intelligible ; while, for want of this, we must also omit 

 all notice of the innumerable veins which maintain this 

 general connection, and indicate the former greater ex- 

 tent of trap in Scotland. In the south, the rocks of this 

 class become rare ; and we need only here notice the 

 Eildon Hills, and the Cheviot scarcely appertaining to 



Scotland. 



Mineral- 

 ogy- 



nerals was drawn up by the writer of this article, and Statistics. 

 was first published in Dr. Brewster's Journal oj Sci- *^**-yr^t 

 ence, vol. i. p. 225. Mineral 



CSV. 



QUARTZ. 



*'' 



Of this very common mineral, it is only necessary to Quartz, 

 notice the varieties which are rare, and which more 

 particularly comprise those that present peculiarities of 

 colour. 



Foetid. At Pol Ewe and Loch Greinord, on the 

 western coast of Scotland. This is found in gneiss, 

 forming veins, and the smell often resembles that of 

 putrid sea weed. It is sensible only on friction, and 

 diminishes when the specimens have been so long kept 

 as to lose their water. 



Green. Coloured by chlorite. In Bute ; on the 

 shore of Cowal ; on the south-eastern shore of Jura, 

 and on the north-western of Jsla, opposite. This 

 quartz forms veins in chlorite schist, and is always ac- 

 companied by common chlorite. Some of the varieties 

 are so dark as to be nearly black. It has been mis- 

 taken for prase, from which it is essentially different. 

 The following variety is the prase of the Germans. 



Green. Coloured by green actinolite. Prase. I 

 have found this variety only once, and it was in a very 

 limited quantity even there. This Avas in a small isl- 

 and within, and not far from the entrance of Loch 

 Hourn. As it is too insignificant to have a name in 

 the map, I cannot direct mineralogists to it more ac- 

 curately. This quartz is in veins, traversing actino- 

 lite schist ; and, according to the quantity of the inter- 

 mixed colouring matter, it varies from a very light to 

 the usual dark green of this mineral. 



Green. Coloured by the green earth of the trap 

 rocks. In Rum, in Scuir-more, together with the he- 

 liotrope of that place. In Glen Farg, and in the hill 

 of Kinnoul. It also occurs in Ayrshire; and general- 

 ly, in this case, it is intermixed with other chalcedo- 

 nies and agates. 



Green. Coloured by an intermixture of green com- 

 pact felspar. In Rona, (East) at Pol Ewe, and on va- 

 rious parts of the western coast of Ross-shire. 



Pink. Opaque, and pink or flesh-coloured. Com- 

 mon quartz, coloured by an unknown ingredient. In 

 Lewis, from gneiss. 



Pink. Opalescent, or rather milky. In Coll ; in 

 Aberdeenshire, on the Buck of Cabrach. The latter 

 specimens are nearly transparent. In Loch Maddy in 

 North Uist. 



Brown red. Transparent. Apparently coloured by 

 iron. On the western coast of Sutherland, in veins 

 traversing gneiss, between Loch Inver and the Ru. 

 Storr. In East Rona ; in the Angus hills. 



Brown red. Milky or chalcedonic quartz. At Gair- 

 loch in Ross- shire, in gneiss. 



Purple or lilac. Opaque. In Shetland, near Selie- 

 voe, in gneiss. 



Violet blue. Pale ; opalescent. In Loch Maddy, in 

 North Uist, in gneiss. 



Purple. Crystallized; amethyst. In trap in the 

 hill of Kinnoul, and elsewhere ; found in the centre of 

 agate nodules. In the hills of Mar, in granite. 



Grey. Blue or French grey. Opaque. In Glen 

 Tilt, in veins in gneiss ; and in Aberdeenshire. 



Grey. Blackish. Common quartz, irregularly trans- 

 parent. In various parts of Aberdeenshire, and in 

 Shetland. 



The following list of some of the rarer Scottish mi- 



* Several new minerals recently found in Scotland, and others wh'ch have been separated from old species, are added to this list Ei>. 



