The ore is found in a sort of chloritic slate and iron pyrites which follow the ledge all around. The ore itself is a fine-grained pyrite, with a grayish color, and it is well suited by its sulphur and low copper contents, as well as by its properties for heap roasting. In heap roasting, the ore is hand-broken by workers into small lumps before being hoisted to the surface. From the landing on the surface it is run out on long tracks under sheds, dumped around a loose brick flue and on a few sticks of wood formed in the shape of a V, which runs to the flues to give a draught. Layers of brush are put on at intervals through the pile. The smaller lumps are placed in the core of the heap, the larger lumps thrown upon them, and 40 tons of tank residues thrown over all to exclude excess of air; 500 lb. of salt is then distributed through the pile, and it is then set afire.

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