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It may be taken as a general rule that wherever the true serpentine occurs asbestos will be found, though it is difficult to say how the veins have been formed, or how the fact of their existence is to be known with any degree of certainty, except by the light superficial indication already mentioned, which seems at present to be the only, but by no means infallible, guide. The asbestos traverses the serpentine in irregular veins ranging from mere threads or stringers to a thickness of three or four, and in some cases it is asserted of as much as six inches; the fibre always, unless affected by the dislocation of the containing rock, lying at right angles to the sides of the fissure.

The rock is often impure, the impurity arising mostly from the admixture of particles, occasionally of small irregular thread-like veins, of magnetite or of chromic iron, which break the continuity of the fibre and cause very careful cobbing of the ore to be necessary in order to get rid of these impurities. This is particularly the case at Thetford, as we shall see when speaking of Messrs. King's mine there.[7]

In other districts the fibre is discoloured (and the value of it consequently much reduced) by the infiltration of water impregnated with the oxide of iron. This is especially the case in the Black Lake district, more particularly on the property of the Anglo-Canadian Company, where the serpentine is a good deal shattered by the action of the weather, or possibly from other causes. This discoloration ceases as a general rule, or at any rate becomes considerably diminished in intensity, in proportion as the containing rock becomes more solid. It is, however, a most serious matter as affecting the character and pecuniary value of these mines.

In the case of nearly all the mines there are large quantities of so-called bastard asbestos found in and about them. This is a woody, brittle variety of apparently as yet unformed mineral, for which at present no use seems to have been found; but, judging from the course new applications of the mineral are now taking, there can be little doubt that this inferior article will presently command its price in the market, a use being found for it in some of the many purposes for which coarse pulverized asbestos is found to be applicable.

Many other very singular types are also to be seen. Some of the pieces as they lie on the ground, after blasting, have so much the appearance of a wood-cutter's choppings (being, in fact, in the coarse and peculiar grain of the fibre, so like chips of wood), that, if placed side by side with actual chippings from rough timber exposed to the weather in the woods, the one could in no way be distinguished from the other, except of course by handling, when the weight and stony feeling of the asbestos would make the difference at once perceptible.

Chrome iron is frequently found, sometimes as at Thetford and South Ham, in very large quantities in close proximity to the asbestos-bearing rock. In the iron, where this is the case, although the stringers of asbestos may be very minute, they will almost certainly be found intersecting the ore, just as we have already seen that the grains and threads of the chrome iron often cut and spoil the fibre of the asbestos.

The marketable value of asbestos is determined in the first instance by the colour, coupled with the thickness or width of the fibre in the vein. The colour, it may be said, largely depends upon the locality of the mine, and will be distinguished at once on inspection of the rocky gangue. At Thetford it is of a greenish hue, being there found in the darker coloured serpentine; whilst at Broughton the ore is of a pearly yellowish green, the surrounding rock being mostly of a grey or pale green colour. This difference of colour in the ore, however, in no way affects the value of the mineral, as when crushed out the fibre is mostly of a uniform whiteness.

There are other distinguishing characteristics in the ore even of closely adjacent mines, of so marked a nature that an expert has no difficulty in determining the locality of the mine, or even of the mine itself, from the appearance of the ore.

Although scarcely within the scope of the present remarks, it is worthy of note that serpentines of an ornamental character are very abundant in Canada; some very beautiful specimens of which were recently shown in London, at the late Colonial and Indian Exhibition at South Kensington. Many of these contain small quantities of chromium and nickel, and are associated with soapstone, potstone, dolomite, and magnetite. A band of limestone also occurs at Templeton containing masses of a light-coloured translucent serpentine. These, however, beautiful as they are, do not at this moment specially concern us, as none of them contain asbestos in workable quantities, the stone being entirely of an ornamental character. They are exploited with some success by the Canadian Granite Company of Ottawa, and are used by them for monuments, mantelpieces, vases, and such like. One would certainly think that their importation into England would meet with success, seeing that there is always a demand here for fine marbles and stones for architectural and other purposes.

Sir William Logan says: "Les serpentines, dans toute l'étendue de leur gisement, fournissent de très-beaux marbres vert-de-mer souvent ressemblant au vert antique."

THE THETFORD GROUP OF MINES.

Although the existence of asbestos in Canada, in one at least of the above-mentioned localities, was known to geologists for many years prior to 1877, it was not until the autumn of that year that a mine was discovered which proved to be of any commercial importance. This was first found by a farmer, named Fecteau, in the township of Thetford; and, true to its reputation, Thetford has continued to be the head-quarters and main source of the supply ever since.

This, the first regular Canadian mine, was opened up in 1878 by Messrs. Johnson and Ward. The demand at first for the produce of this mine was exceedingly limited; indeed, great difficulty was experienced in finding a market at all. The output the first year was only about fifty tons; but the great value of the mineral being soon ascertained, exploration on the serpentine belt in this neighbourhood was prosecuted on an extensive scale, which resulted in asbestos being found in workable quantities over a very considerable area.

The mine spoken of is now the property of the Johnson Company, of which the Hon. George Irvine, Q.C., is president, and Mr. Andrew Johnson, who now represents Megantic in the Provincial Legislative Assembly at Quebec, is the resident manager. The features of this and the neighbouring mines are very similar. They consist of a massive serpentine, varying in colour from a dark green to almost white, intersected by numerous veins of asbestos of varying thickness, remarkably free (except in one instance) from any admixture of foreign substances. A large extent of this mine is now opened. It is being worked with energy and success, its produce being second to none that has yet been put on the market. According to a statement given in the Canadian Mining Review for October last, its output for 1886 was approximately 375 tons, the total output of the mine up to the end of that year being given as 2,500 tons. I was recently informed by the president of the company that they had now made a contract