Large tracts of serpentine, probably containing the mineral in paying quantities, occur at Belmina in Wolfe County, and in the vicinity of Brompton Lake; but although the work of exploration has been carried on in several places with fair prospects of success, the profitable working of the mineral up to the present time has been mostly confined to Broughton, Thetford, Coleraine, and Danville.
In the Shickshock mountain region of New Brunswick, said to be a detached area of the pre-Cambrian formation, which constitutes the chief mineral belt of the Eastern Townships (within which the last-mentioned districts are comprised), serpentine and chromic iron are the only two minerals which have as yet been recognised. Looking, however, to the fact that these two minerals everywhere accompany the deposits of chrysotile, as well as the ores of copper, lead, and antimony, with occasionally richer deposits of gold and silver, in the region to the south-west, it would scarcely seem unreasonable to anticipate discoveries of asbestos in the as yet unexplored region of the Gaspé peninsula. The range here extends through the northern portion of the peninsula in rear of Saint-Anne des Monts, and further east on the lower part of the Dartmouth River.[5]
Indications of asbestos are found at most points throughout the whole serpentine formation. The developments, so far as is yet known, are principally, as we have said, in the districts around Thetford and Coleraine. There can, however, be no valid reason why chrysotile of the richer sorts and in paying quantities should not be found at other points, it being only reasonable to suppose that future exploration will materially extend the area over which profitable mining operations can be carried on.
In the Blue Book on the "Geological Survey of Canada, 1882" (Mr. Willimott's report), published by the Dominion Government, it is stated that "there appears to be unlimited quantities of asbestos distributed throughout the entire serpentine belt which attains its greatest prominence in the townships of Thetford and Coleraine. Its existence is generally made apparent by a whitish shining substance found coating the serpentine, arising from the decay of the outcropping veins. But this," he says, "must not be taken as always indicating the presence of workable veins."
The character of the rock varies considerably, and in some places it is even now apparently in the transition stage between the original rock from which it is derived and a true serpentine, having still almost the hardness of felspar, while it yet retains the general aspect and colour of the serpentine in which it is found. Large masses of dioritic rock, having the aspect of dykes, are found in most of the quarries, possibly representing portions of the original rock not yet altered to serpentine.[6]
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.