Fire-setting was a mining method in which rock was heated until the fire weakened its inner structure and made…
Fire-setting was a mining method in which rock was heated until the fire weakened its inner structure and made it crack. Sometimes, after the stone had been heated, miners poured on cold water or vinegar; the sudden change in temperature, or the action of the vinegar itself, would cause the rock to split. Zhu Mu's Territory Gazetteer of the Song dynasty records that on Guangming Mountain in Yuanling, Chenzhou, where cinnabar was mined, the locals "burned the stone to take it out." It also says that frontier peoples "used wood and bamboo as fuel to blast the rock and extract the ore."