# Mercury extraction > Freeing quicksilver from cinnabar - Date: c. 315 BCE - Era: Antiquity - Domain: [Materials & Chemistry](https://lastcodex.org/en/domains/materials/) - Rebuild stage: III (Crafts & cities) - Difficulty: 4/5 - URL: https://lastcodex.org/en/inventions/mercury-extraction/ Mercury, the only metal that is liquid at room temperature, is won almost entirely from cinnabar, a red ore of mercury and sulfur that gives up its metal as a vapour when heated. The oldest known description of making it from cinnabar was written by the Greek Theophrastus in about 315 BCE. For centuries the great mines of Almadén, Idrija and Huancavelica supplied the mercury that refined American silver, at a heavy cost to the health of their workers. ![Mercury extraction · Freeing quicksilver from cinnabar](https://lastcodex.org/_astro/plate.htZU0FL8_Zo05CS.webp) ## Legend 1. Cinnabar ore 2. Furnace 3. Rows of clay aludels 4. Liquid mercury ## What it is Mercury is a heavy, silvery metal that stays liquid at ordinary temperatures, which earned it the old name of quicksilver. Small drops of it occur in its ore, but nearly all of it is obtained from cinnabar, a bright red compound of mercury and sulfur. Ground to powder, cinnabar is also the red pigment vermilion. ![A specimen of rock with clusters of deep red cinnabar crystals on white stone, resting on a small wooden stand](https://lastcodex.org/_astro/v1.9KeVujL0_1GomqH.webp) _Cinnabar, the red ore of mercury and sulfur from which nearly all mercury is won._ Mercury dissolves gold and silver into soft alloys called amalgams, and this made it valuable to miners: an amalgam collects fine particles of precious metal, which are recovered when the mercury is driven off again. It also went into the backing of [mirrors](/en/inventions/mirror/), into [thermometers](/en/inventions/thermometer/), and into many medicines and chemicals. Its vapour is a poison. Breathed in over months or years, it damages the nervous system and the kidneys, and mercury that reaches rivers is turned into compounds that build up in fish. Extracting mercury exposes the workers and the land around the works, and the Minamata Convention on Mercury, in force since 2017, forbids opening new mines and gives existing ones fifteen years to close once a country has joined. ## How it works ![A pear-shaped pipe of fired clay, open at both ends, lying on a wooden bench](https://lastcodex.org/_astro/v2.Uq6SA43o_Z2md26O.webp) _An aludel, one of the clay pipes of the seventeenth-century mercury furnaces._ Cinnabar holds its mercury firmly, but heat breaks the compound apart and releases the mercury as a vapour, which turns back into liquid metal as it cools. Every furnace for mercury has the same two parts: a hearth that heats the ore and a condensing system that cools the vapour. In the aludel furnaces of the seventeenth century, this system was made of rows of aludels, pear-shaped pipes of fired clay. The old furnaces leaked and were often opened before they had cooled, so much of the metal escaped into the air and the furnace workers breathed its vapour. Modern plants work continuously and keep the gases inside closed equipment, but they too are run only as licensed industrial works. ## History and evolution Cinnabar was prized as a red colour long before anyone wanted its metal. Aristotle mentions the liquid metal, and his pupil Theophrastus, in his book On Stones, written in about 315 BCE, gives the oldest known description of making it from cinnabar, by a method that needed no fire. Vitruvius and Pliny the Elder, in the first centuries BCE and CE, describe mercury freed from cinnabar by heat. Pliny also records that the most prized cinnabar came to Rome under seal from Sisapo, in the province of Baetica, whose mines lay in the district of Almadén in central Spain. ![A paved courtyard of stone where a thick layer of grey ore mud is spread out, with two horses walking through it, beside the low adobe walls of a colonial hacienda](https://lastcodex.org/_astro/v3.YqCvPZt0_29HBj7.webp) _A patio yard of New Spain, where mercury drew the silver out of the ore._ Almadén was worked for more than two thousand years. In about 1490 a second great deposit was found at Idrija, in present-day Slovenia. Demand grew in the 1550s, when Bartolomé de Medina, at Pachuca in New Spain, put into large-scale use the patio process, which used mercury to draw silver out of its ore on large paved yards. In 1564 Spanish colonists began to mine cinnabar at Huancavelica, in the Andes of Peru, and the patio process reached the silver mines of Potosí in the early 1570s; from then until the early nineteenth century, mercury production was driven by American silver. At Huancavelica, in 1633, the physician and prospector Lope de Saavedra Barba built the first aludel furnace, which soon replaced the older furnaces; Juan Alonso de Bustamante brought the design to Almadén, where it first worked in 1646. Huancavelica was worked largely by forced labour under the colonial draft called the mita. Workers and their families were poisoned by mercury vapour and cinnabar dust, and the soil and adobe houses of the town still hold mercury today. As mercury left medicine, instruments and industry, the old mines closed: Idrija produced its last mercury in 1995, and Almadén, where mining stopped in 2001, produced its last in 2003. The two sites have been on the UNESCO World Heritage List together since 2012. Most mercury mined today comes from China, while small-scale gold mining, which still uses mercury to catch gold, has become the largest source of the mercury that human activity releases into the air. ## Key facts - Oldest description of extraction: Theophrastus, c. 315 BCE - Almadén worked: For more than two thousand years - Aludel furnace: Huancavelica, 1633; Almadén, 1646 - Last mercury from Almadén: 2003 (mining stopped in 2001) ## Requires - [Mining and Quarrying](https://lastcodex.org/en/inventions/mining/): Reaching minerals underground and keeping the workings safe (46,000 years ago) - [Control of Fire](https://lastcodex.org/en/inventions/control-of-fire/): Light, heat and cooked food (1 million years ago) - [Pottery](https://lastcodex.org/en/inventions/pottery/): Clay turned to stone by fire (20,000 years ago) ## Leads to - [Rotary mercury vacuum pump](https://lastcodex.org/en/inventions/rotary-mercury-vacuum-pump/): Emptying lamps with a drum turning in mercury (1893) ## Sources - [Mercury and its compounds in ancient times (Journal of Chemical Education 5, 1928, pp. 419–424)](https://pubs.acs.org/doi/10.1021/ed005p419), Earle R. Caley, American Chemical Society - [Lithika: Ancient Medical and Technical Texts on Stones (CAMWS 2016; dates On Stones to about 315–314 BCE after Eichholz 1965)](https://camws.org/sites/default/files/meeting2016/179.Lithika.pdf), Classical Association of the Middle West and South - [Mercury](https://periodic-table.rsc.org/element/80/mercury), Royal Society of Chemistry, Periodic Table - [Exploring the ancient chemistry of mercury (PNAS 119, 2022)](https://pmc.ncbi.nlm.nih.gov/articles/PMC9214491), M. Marchini, M. Gandolfi, L. Maini, L. Raggetti, M. Martelli, PNAS - [Chemists and historians recreate ancient alchemy of making mercury](https://www.chemistryworld.com/news/botanists-chemists-and-historians-come-together-to-recreate-ancient-alchemy-of-making-mercury/4015894.article), Chemistry World, Royal Society of Chemistry - [Pliny the Elder, Natural History 33.40 (trans. J. Bostock and H. T. Riley)](https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.02.0137:book=33:chapter=40), Perseus Digital Library, Tufts University - [La investigación arqueológica de los paisajes mineros antiguos en la vertiente norte de Sierra Morena (provincia de Ciudad Real)](https://portalcientifico.uned.es/documentos/5f88eb1029995259ef297e8d), UNED, Portal científico - [Heritage of Mercury. Almadén and Idrija](https://whc.unesco.org/en/list/1313/), UNESCO World Heritage Centre - [Heritage of Mercury. Almadén and Idrija: nomination dossier](https://whc.unesco.org/uploads/nominations/1313rev.pdf), UNESCO World Heritage Centre - [Papel de España en relación con el mercurio](https://www.miteco.gob.es/en/calidad-y-evaluacion-ambiental/temas/productos-quimicos/mercurio/papel_espana_mercurio_ctndm.html), Ministerio para la Transición Ecológica y el Reto Demográfico - [Idrija Mine Museum](https://www.culture.si/en/Idrija_Mine_Museum), Culture.si, Ministry of Culture of the Republic of Slovenia - [Implantación de los hornos Cermak-Spirek y Spirek en la metalurgia de las minas de Almadén (Llull 37, 2014, pp. 115–145)](https://dialnet.unirioja.es/descarga/articulo/4687125.pdf), J. Tejero Manzanares and L. Mansilla Plaza, Universidad de Castilla-La Mancha - [Intercambio de expertos y técnicas mineras referidas al azogue entre ambos lados del Atlántico durante el periodo colonial](https://ihtc.orex.es/1745.pdf), M. Silvestre Madrid and E. Almansa Rodríguez, Universidad de Castilla-La Mancha - [Mercury Production and Use in Colonial Andean Silver Production: Emissions and Health Implications (Environmental Health Perspectives 120, 2012)](https://pmc.ncbi.nlm.nih.gov/articles/PMC3346781), N. A. Robins and N. A. Hagan, NIEHS - [The global roots of pre-1900 legacy mercury (PNAS 120, 2023)](https://pmc.ncbi.nlm.nih.gov/articles/PMC10400983), S. Guerrero and L. Schneider, PNAS - [Bartolomé de Medina](https://miningeducationfoundation.org/Bartolome_de_Medina), Mining Foundation of the Southwest, American Mining Hall of Fame - [Indigenous Technical Literacies and Data Sovereignty: Some Problems in the History of Science and Digital Humanities](https://www.1718.ucla.edu/wp-content/uploads/2019/03/Bigelow_Paper.pdf), Allison Bigelow, UCLA Center for 17th- and 18th-Century Studies - [Mercury and health](https://www.who.int/news-room/fact-sheets/detail/mercury-and-health), World Health Organization - [The Minamata Convention and the Future of Mercury Abatement (Issues in Brief 28, 2013)](https://www.bu.edu/pardee/files/2013/09/Pardee-IIB-028-Oct-2013.pdf), Henrik Selin, Boston University Pardee Center - [Minamata Convention on Mercury: text and annexes](https://minamataconvention.org/en/resources/minamata-convention-mercury-text-and-annexes), UN Environment Programme - [Mineral Commodity Summaries 2025: Mercury](https://pubs.usgs.gov/periodicals/mcs2025/mcs2025-mercury.pdf), U.S. Geological Survey Fact-checked on 2026-10-22. --- The Last Codex · https://lastcodex.org/en/inventions/mercury-extraction/ · © The Last Codex. Texts, plates and figures: CC BY-NC-ND 4.0.