What is the cupel used in metal refinery called?

The cupel used in metal refining is typically called a "cupel." It is a porous container made from materials like bone ash or clay, designed to absorb impurities during the process of fire assay. In this process, precious metals like gold and silver are separated from base metals, allowing for the recovery of pure metal. The cupel's ability to absorb lead and other oxides is crucial in achieving high purity levels in the refined metal.