Cinnabar
Mercury sulfide — the only ore of mercury worth mining, and the source of vermilion, the most brilliant red available to painters for two thousand years.
Cinnabar is mercury sulfide, and it is unusual among ores in giving up its metal almost trivially: roast it in air and the mercury leaves as vapour, to be condensed as a liquid metal. That simplicity is why mercury was known and used in antiquity when far more abundant metals were not.
It is also the source of vermilion. Ground cinnabar gives a red of a saturation nothing else could match before synthetic pigments, and it was used from Roman wall painting through to the illuminated manuscript and the Chinese lacquer tradition.
How to identify it
The scarlet streak is decisive and separates cinnabar from every other red mineral — hematite's streak is a duller red-brown, and realgar's is orange. Cinnabar is also very heavy for a soft mineral, at around eight times the density of water and a hardness of only 2 to 2.5.
Environmental impact
The mineral itself is poorly soluble and comparatively inert; the hazard is what is done to it. Roasting releases mercury vapour, and historic mining districts — Almadén above all, worked for two thousand years — carry mercury contamination that will outlast any remediation planned for it.
Mercury's toxicity was understood early and the mines were worked by forced labour for much of their history, which makes cinnabar one of the clearer cases of a material whose cost was paid by people who had no say in it.
How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.
How this connects
Where a connection has been confirmed by an outside reference, that reference is named beside it.
is an ore of
- Mercury — element · essentially the only ore; roasting it in air releases the metal as vapour, which is condensed Wikidata
is an input to
- Roasting — process · roasted in air; the mercury leaves as vapour rather than staying behind as an oxide
is a component of
- Epithermal vein — deposit type · at the top of the sequence, mercury being volatile enough to travel furthest before the fluid drops it
Sources
- Material WorldOur own writing
- Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
- COD Advisory Board / Vilnius University · CC0 — contributors place data in the public domain