An unusual copper smelter at Coed-y-Brenin.
According to the National Museum of Wales "Coed-y-Brenin, Dolgellau, Gwynedd: copper occurred at the Turf Copper Mine, impregnating/replacing decayed vegetable matter in a peat bog fed by groundwaters percolating through the Coed-y-Brenin porphyry-copper deposit."

Peat was burned in the smelter to obtain small amounts of copper.