Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/148

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Mr. William Phillips on the Veins of Cornwall.

completed an account of it, to present it to the Geological Society.

In describing that effect produced by the interruption of one vein by another, called the heave, it ought to be noticed that a copper vein going down with a quicker underlie than a tin vein, always passes through it, and sometimes interrupts its regular course. And if the underlie of the copper vein be south, and that of the tin vein north, or vice versa, the copper vein continues its course, but interrupts that of the tin vein, heaving it out of its first direction; and although Pryce has merely given the appellation of ‘Gossan’ to those veins that heaved the tin veins, as just noticed, it seems to me probable that these ‘Gossans’ were veins containing copper, which is rendered the more so, as the term ‘Gossan’ is frequently given to a copper vein, merely from its being the prevailing substance. The heave of a tin by a copper vein was, I believe, one of the remarkable and complicated disasters which befel the veins in Huel Peever.

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A small metalliferous vein or string is sometimes found to take the same course as the east and west vein, (Pl. 6. fig. 3.) When its underlie is so much quicker than that of the latter, as to overtake it in going down, the metalliferous vein is generally found to increase in size, not merely in the proportion of the addition of the lesser vein, but very much more, so as to make a great body of ore, called by the miner a gulph of ore at their junction. This species of vein is therefore termed a Feeder.

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While working in the course of a load, small metalliferous