Asbestos, Its production and use / With some account of the asbestos mines of Canada

by Robert H. Jones

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 for the sale of the whole of their output for the next five years. The produce of the mine is nearly all No. 1, and is worth from $80 to $100 a ton.