stone, but there can be no doubt from the knowledge we possess, of the material of which it is chiefly composed, that it is eminently suited for that purpose: but were it only valuable in proportion to the quota it furnishes, in the composition of that invaluable material, the finest kind of glass, it would be well worth a high place in our estimation.*

But what is this most abundant formation, yet not more abundant in extent than infinite in variety-in all its shades, and tints, and complexions, and hues, from the beautiful snow-white of the island of Paros,-and the brilliant and sparkling variety of the same colour, that comes from the neighbourhood of Carrara,† down

Quartz is also used in the manufacture of porcelain, for which purpose great quantities are collected from the mountains of Wales, ground into powder, and in that state shipped for Liverpool and other parts; and in this state after being burnt, it is sometimes mixed with clay and formed into bricks for the construction of glass furnaces.

†The varieties of marble may well, indeed, be said to be almost infinite. No mineral in the creation affords such a number of diversities, and none has so much attracted the attention of mankind. It was in the Ruso Antico, the ancient red marble of Upper Egypt or Ethiopia, many of the Egyptian monuments and statues that are found in the museum of Paris, were executed, as well as nearly all the sublime subjects of the Grecian and many of the Roman artists. The marble of the island of Paros seems to have been in greatest estimation for the purposes of statuary; and next to that may be reckoned the brilliant species already noticed, which is to this day obtained from the neighbourhood of Carrara; to which may be added, that a quarry of marble of extraordinary beauty, is said to have been lately discovered near Meran, in the country of Tyrol, which in the whiteness and fineness of its grain, will bear comparison with the best marble of Car. rara; but there is such a choice variety of beautiful marbles to be met with in our own native country for every useful and ornamental pur

to that black kind which is extracted from the quarries of Bakewell in Derbyshire, and which is susceptible of so fine a polish, as to be capable, of being converted into a mirror by that operation alone. It is marble!—yes; that very marble, of which we learn the antiquity for useful and ornamental purposes, in the Book of Esther, where, we are told, that the palace of Ahasue rus had pillars of this mineral, and that there was a pavement of "red, and blue, and white, and black marble."

There is but one rock more that I mean to notice before I pass on to the slaty varieties of this description, and that is serpentine; so called from the resemblance, this elegantly beautiful and singularly pleasing for mation, bears in its tints and shades, and delightful admixtures and play of colours, to the skin of that wily creature from which it derives its name.

pose, that we need neither go to the Archipelago-to the neighbourhood of Athens-to the vicinity of Sienna-to the Verdi di Prado-to the newly discovered quarry in the Tyrol—or to any other country, either in the old or new world, for marbles. The fine white statuary marble of Assint in Sutherlandshire, "is (says Mr Williams,) the purest and best I ever saw ;" and he describes another to be met with a few miles from Blairgowrie in Perthshire, of an excellent granulated texture, and which he looks upon as a species of the true Parian marble; when to these are added, the beautiful variety of English, and Irish, and Scottish marbles, that we, in so many places meet with, not forgetting the pale red-spotted with green hornblende marble of Tiree, and other coloured varieties of beautiful tints and resplendent hues, we need not be surprised at the regret so pointedly expressed by this author, that we should send to foreign countries for stones, for the purpose of ornamental architecture, when perhaps no country can produce so great a variety of the most excellent stones as are to be found in Britain.

Williams' Min. Kingdom, vol. i. p. 405 and 406,

Serpentine, on this account, may be also said to be nearly allied to marble ;-indeed, these two splendid productions of nature, are sometimes blended together, and the joint production, instead of diminishing, may be said to enhance, as in the case of the Italian Verde Antique, the beauty of both.*

These (with two or three others, which, on account of the very limited extent they have yet been found to occupy, or the near resemblance they bear to some of those I have just enumerated, which, in a manner identify their uses, I shall pass over,) may be said to constitute the whole of the more solid and compact kinds, of what naturalists call primary formations.

THE SLATY KINDS OF PRIMARY ROCKS.

But there is another description, to which we shall turn our attention for a few minutes, and which, were it only for the rich and capacious beds of metallic substances they contain, are well deserving our consideration in passing. These, indeed, may be well defined, to be the principal metalliferous depositories among the lower formations of the earth,-for although, in a smaller or greater degree, they may be found in most of those I have already mentioned; and the richest mines at

Serpentine, though by no means to be met with in such quantity in Britain as marble, is nevertheless to be seen in characteristic beauty, forming part of the Lizard promontory in England. It is also to be met with in the island of Anglesea in Wales, and at Portsoy in Banffshire, from which place I have a beautiful specimen in my posses. sion. As an ornamental stone, it may be applied to a number of the same uses as the coloured or variegated marbles, and like them, we can be supplied with it in abundance, without going beyond the verge of the British isles.

present known, those of Mexico in America, as well as the mines of Hungary, the most considerable in Europe, are situated in porphyry, yet, in the slaty formations, the metals may be said to superabound; and, we cannot but, therefore, admire the wisdom and beneficence of the contrivance, which, in sinking these repositories so low as many of them are found to be, has, nevertheless, given us so easy access into their capacious bowels, by their slaty and foliated structures.

Gneiss, or slaty granite, is found almost in every country where granite occurs; and we may judge of its value, as a metallic depository, when we are informed by Professor Jameson, that all the useful metals, with the exception of mercury, occur in this rock."*

In mica slate, the gold mines at the foot of Mount Rose, as well as some of those in the country of Salzburg, are principally situated.+

Clay slate is also rich in metals, and is a very widely extended rock, and in the greenstone slate, the celebrated mining district of Gersdorf in Saxony,-and the mining districts of Rudolstadt in Silesia, are situated.‡

* Manuel of Mineralogy, p, 358.

The old mines of the ancients, in the neighbourhood of Athens, were situated in Gneiss,—and, at the present moment, the great iron mines in Norway, Sweden, and Lapland, and the most valuable mines in Saxony, Bohemia, and Salzburg, are surrounded by beds of it, as were the lead mines of Strontian in Argyleshire, when they were worked with so much activity some years ago.

And, it may be added, the silver mines of Johan-Georgenstadt, and Braunsdorf in Saxony,-those of Sweden and Norway, and many in Silesia and Bohemia,—as well as the mines of Dalecarlia and Fablun, in Sweden; and many in other parts of Europe, are to be found in the same rock.-Ibid, 361.

But it is not merely as depositories of the metals, that these slaty

The whole of these, including the few that I have not dwelt upon, for the reasons formerly mentioned, are called by naturalists, primitive or primary formations; -and these, as I have already observed, form the basis upon which the other orders of rocks rest ;-for although some of the other descriptions are occasionally found enveloping and overtopping these,-yet, by digging in a vertical or diagonal line, through the various strata that environ and thicken about the basis of primary mountains, they will be found to be composed of materials of a very different description, and to recline and rest upon the others, as upon a centre or nucleus.*

It is by these naked rocks, of such durable materials,

and laminated formations administer their services. "In some parts of Siberia, mica is copiously quarried, and is employed as a substitute for glass in windows and lanterns;"† while the extreme tenuity of the plates into which it may be divided, and their elasticity, render it very useful for the enclosure of objects to be submitted to microscopic inspection ;§-and if we turn our eyes to those immense numbers of slates extracted from the quarries in North Wales, and near Kendal in Westmoreland,―or from those still more extensive depositories, situated in what are called the Slate Islands in the west of Scotland, we must at once see the importance of this species of slaty formations, the uses of which, in roofing our habitations,-furnishing us with slabs for cellars and diaries,—writing slates and pencils,—are too well known to need description. † Brande, p. 42. § Ibid.

Thus, although mica slate, and clay slate, and primitive limestone or marble, forming so many separate strata, may all be found surrounding, and resting upon the granitic nucleus, or centre pillar of a mountain,-some of the transition, and secondary class, in their turn, may be supposed to surround and rest upon these,-while these again must submit to be clothed by the alluvial depcsits that succeed,—till all be covered, except where the naked peaks of primitive formation will not submit to the operation, in the same flowery mantle !

M