It must, however, be borne in mind that the same rule obtains with many other things as is noted in the vegetable world—namely, that the largest specimens are not necessarily the best. The broader veins of asbestos do not, as I have already remarked, yield as a rule fibre of so fine a quality as those of a medium, or even of a small size. The length of the fibre, moreover, cannot be determined with any absolute certainty from the thickness of the vein. On the contrary, the broader veins are not seldom found to be separated at right angles to the length of fibre by minute bands of serpentine, chrome, or magnetite, sometimes even by a separation without any perceptible layer of rock, the only indication of this being an irregular, scarcely visible line, readily detected by the expert.[9]
Under the hammer the big veins, in which the separation exists, are at once divided into two, or it may be into three lengths of fibre; but if the cotton be pure and clear, this is no very great detriment. Veins of an inch or an inch and a half extracted from compact rock seldom have these intersections. The veins, moreover, are extremely irregular in character, a small vein at the surface frequently developing into one of considerable size lower down, or breaking off altogether. This is the special characteristic of the veins in the Coleraine district—notably at Black Lake—at the mines of the Anglo-Canadian Company, and at Danville. At Thetford, on the other hand, where the ground is of a more uniform character, and at a lower level than at Black Lake, fine veins are frequently met with just below the surface, which continue for a considerable distance with very little change.
It will clearly be seen, therefore, that it is not possible properly to appreciate the value of such a mine as this without inspection and thorough examination by an expert. Fine specimens can at any time be obtained, and have before now been exhibited at a distance as being the produce of some particular mine for which a purchaser was wanted, when anyone visiting the spot would at once see the utter impossibility of such having been the case; and even if it were proved to be true that the specimens exhibited came from the place indicated, it would be important to know at what depth they were got, with the nature and general disposition of the mine, as well as the proportion of superincumbent rock requiring to be removed before the valuable veins could be worked. Without a knowledge of this it is self-evident that no practical estimate of expense to be incurred could possibly be made.
The discovery at Broughton made a great stir at the time; but the big vein there was to all appearance soon worked out, the supply thought to be exhausted, and work in consequence discontinued.
That, at any rate, was the view taken by the gentleman who then worked the mine. About 130 tons, I was told, were got out, which fetched from $100 to $120 a ton. It would now be worth a much better price.
The Scottish Asbestos Company have since then purchased this property, and from the extensive preparations they are making for work, and the great outlay they are incurring for machinery, buildings, and plant, it is clear that they do not by any means coincide in the view above expressed. The stratification at Broughton is peculiar, and different from anything that is found either in Thetford or Coleraine. It is quite possible, therefore, that the Company's advisers may be right, and that the surface deposits will be found to continue in richness and volume lower down. The developments at present consist of an open cut 15 to 20 feet deep by 8 feet wide following the vein and the serpentine reef is laid open for a length of about 900 feet.
When I last visited Broughton, in the autumn of 1886, I went over the ground in company with the late Mr. Fraser, who was then resident on the property, but was unable, from the quantity of water in the cut, to trace any of the big veins which had previously been worked. It was evident, however, that in consequence of a sudden dip downwards considerable expense would have to be incurred, and much very heavy work done, before the seam could be reached again. The belt of serpentine here is very narrow, and the veins of asbestos are closely pressed together. The strike is east and west, and the dip 30°.
There are prospects here to the north-east, apparently of as valuable a character as those of the mine already opened. A few days after my visit, I was shown some fine samples from the surface work of this place, where the ground had just been stripped, and these bore the precise characteristics of the fine vein already spoken of. The Broughton ore has a pale yellowish hue, as distinguished from the greenish metallic lustre which distinguishes the finer samples from Thetford. This does not, it must be observed, in any way deteriorate or injuriously affect the clear whiteness of the fibre when crushed out, although it at once identifies the locality of its production. There are, in fact, as I have already mentioned, certain peculiarities, even of colour, attaching to the ore of each locality of so marked a character that an expert can at once tell, on inspection, from what locality it was obtained.
There is great abundance of soapstone (steatite) at Broughton; much of it of good quality, and some of it is remarkably pure. I brought away a singular specimen, having all the grain and even the fibrous markings of asbestos, which was nevertheless pure and unmistakable unfibred steatite.
At present no use is being made of this material at Broughton, but at Wolfestown, in the same province, there is a manufactory for its use, and here slabs of very fine quality can be procured. A workable bed of very superior quality has been found also at Potton, and there is another at South Ham, near the antimony mines on the Lake Nicolet estate. Reduced to powder, the softness and unctuosity of steatite have caused it to be used, in the same manner as plumbago, for lubricating purposes, and when finely ground it is employed for giving a surface to some kinds of paperhangings.