Cinnabar occurs as a heavy, brilliant red mineral, historically mined in enormous quantity at Almaden in Spain, at Idrija in Slovenia, and at several sites in China, where it was also known and used from very early antiquity. To extract the metal, miners and metallurgists roasted crushed cinnabar ore in a furnace, where the heat drove off the mercury as vapor, which was then led through a cooling channel or condenser and collected as liquid quicksilver dripping from the far end, one of the earliest and most reliable metallurgical extractions known, requiring only heat rather than any complex chemical reduction. Ground finely without roasting, cinnabar itself served as vermilion, the intense, stable red pigment used in painting, in the red ink of Chinese imperial seals, and in cosmetics, prized for a brilliance that few other red pigments of the period could match.
Alchemically, cinnabar's dual nature, a compound that was simultaneously an ore of the volatile metal mercury and a stable, fixed red mineral, made it an important object of study within the tria prima framework, since it appeared to embody both the fixed sulfur principle and the volatile mercury principle bound together in one substance, and its transformation under fire from red solid to silver liquid was watched closely as a visible demonstration of separating those principles. Vermilion made by grinding natural cinnabar was gradually supplemented and then largely replaced by synthetic vermilion, made by directly combining mercury and sulfur, a process attested from as early as the eighth century in Chinese and later European sources.