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Our next visit was to the very ancient mine of Odin, about a mile to the west of Castleton, at the foot of the Tre mountain, employing about one hundred and forty labourers, men, women, and children. It consists of two levels, running horizontally under the mountain; the upper, a cart-gate, by which the ore is brought from the mine; the lower one, a water-level, to drain it from the works. They penetrate the mountain to more than a mile from the entrance, and are ventilated by shafts sunk into them from above, at the distance of every thirty yards. At the mouth, the level is not more than a fathom and a quarter from the surface of the land; but at the further extremity, above one hundred and fifty. It belongs to several proprietors, and makes great returns. The ore produced here is called potter's ore; its veins usually intersecting the limestone stratum at right angles, which veins are composed of cawk, kevil, and calcareous spar, and sometimes blende, barytes, mangenese, sulphate of iron, native oxyde of zinc, carbonate of lead, combined with lead ore, separated at various depths by the toad-stone, which here stratifies alternately with the limestone. The ore is different in quality, the best yielding about three ounces of silver to the ton weight of lead. The system by which the mine
