Extracting Mercury from Cinnabar — Distillation of Quicksilver from Red Ore

Mercury (Hg, element 80) is the only metal that is liquid at room temperature. Its primary ore is cinnabar — mercury(II) sulfide (HgS), a brilliant vermilion-red mineral containing 86.2% mercury by mass. Cinnabar has been mined as a pigment since at least 7000 BC, and the extraction of liquid mercury from it is among humanity's oldest metallurgical processes. Theophrastus described the procedure around 315 BC, and the cinnabar mines at Almadén, Spain have been operating continuously since at least 400 BC.

The process uses destructive distillation: cinnabar is heated in a sealed retort until HgS thermally decomposes. In the presence of limited air, the dominant reaction is HgS + O₂ → Hg + SO₂, proceeding above approximately 580 °C. Mercury vapor — whose boiling point is 356.73 °C — escapes through a condensation tube, cools, and liquefies as dense, silvery droplets that sink to the bottom of a water-filled collection basin.

EXTREME HAZARD: Mercury vapor is a potent cumulative neurotoxin. Chronic inhalation causes tremors ("hatter's shakes"), personality changes (erethism), kidney damage, and death. Sulfur dioxide (SO₂) is a corrosive respiratory irritant. This process must ONLY be performed outdoors with a full-face respirator rated for mercury vapor and acid gases, chemical-resistant gloves, and protective clothing. Never handle liquid mercury with bare hands. All equipment that contacts mercury is permanently contaminated and must be treated as hazardous waste.