 |
 |
I'm doing a bit of archival work and came across this recently, written by John Whitehurst as part of his very detailed and well thought-out work on the geology of Derbyshire in the late 18th Century: "Thus are the above veins circumstanced: now what is yet more remarkable is this. If a sharp pointed pick is drawn down the vein with a small degree of force, the minerals begin to crackle, as sulphur excited to become electrical by rubbing; after this, in the space of two or three minutes, the solid mass of the minerals explodes with much violence, and the fragments fly out, as if blasted with gun-powder. These effects have frequently happened, by which many workmen have been much wounded, but none killed, both in the eyam mines and in that at Castleton. In the year 1738 a prodigious explosion happened in the mine called Haycliff. The quantity of two hundred barrels of the above minerals were blown out at one shaft, each barrel, I presume, contained no less than three or four hundred weight. At the same time a man was blown twelve fathoms perpendicular, and lodged upon a floor, or bunding, as the miners called it. When the above explosion happened, the barrel, or tub, in which the minerals, &c. are raised to the surface, happened to hang over the engine- shaft, which is nearly seven feet wide, and five or six hundred yards from the forefield, or part, where the explosion happened; this barrel, though of considerable weight, was lifted up in the hook in which it was suspended; and the people on the surface felt the ground shake, as by an earthquake. Such are the effects which have frequently been produced in all the above mines; but from what cause they proceed I have not yet been able to discover, nor even the least traces towards it. When these wonderful effects first happened they deterred the workmen for some years from venturing to work the mines, but afterwards they availed themselves of this extraordinary property. A man would go to the forefield, give a scratch with his pick, and run away; by which means he loosened as much of the minerals as could have been done by common workmanship with ten men in three months. These curious observations I received from Mr. Mettam of Eyam, overseer of the mines, who also addressed the following account of them to Mr. George Tissington of Winster." List members may have seen this before but I found it a fascinating read - sounds like some kind of rock-burst. Apparently the ore-ground where such events occurred was heavily slickensided. Cheers - John