Litharge forms as a natural byproduct of cupellation, the process of refining silver from lead-bearing ore by melting the lead under a blast of air, which oxidizes the lead to litharge while the more chemically noble silver remains behind as a separate metallic bead; the yellow-orange litharge that skims off or crusts the cupel was collected as a useful material rather than discarded, since lead oxide had its own considerable value. Roasted further at a higher, sustained heat, litharge oxidizes still more to become minium, a brilliant red-orange powder distinct enough in color and in composition to be treated, in most craft and alchemical contexts, as its own named substance rather than simply as more thoroughly roasted litharge, even though the alchemical literature is well aware the two are related products of the same basic operation applied with differing intensity.
Minium's brilliant red made it an important pigment from antiquity onward, used in painting and famously in the red initial letters and decorative details of illuminated manuscripts, a practice common enough that the word miniature, for a small illustrated image, derives from minium rather than from any sense of small size. Litharge itself found extensive use as a drying agent mixed into oil paints and varnishes, as a glaze ingredient in ceramics, and as a flux in various metallurgical and glassmaking processes, its usefulness independent of whether it was further processed into minium or used directly.