The pyrite ore bodies are essentially conformable with the bedding of enclosing rhyolitic pyroclastic rocks, which are underlain by rhyolitic flows and conformably overlain by lower Carboniferous shales. The occurrence of the deposits at the same stratigraphic horizon in a west-trending belt over 100 km long and the character of the host rocks suggest that the metals were supplied by submarine volcanic activity during early stages of marine sedimentation. The ore bodies were subsequently buried beneath a thick sequence of shale and were subjected to fracturing and recrystallization, probably accompanied by some redistribution of metals, during metamorphism associated with Hercynian folding and granitic intrusion.

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