sulfides
Cinnabar
HgS
- Also known as
- vermilionChina red
- Crystal system
- trigonal
- Hardness
- 2–2.5 on the Mohs scale
- Lustre
- adamantine
- Colour
- Scarlet to brick red
- Where it forms
- Around hot springs and volcanic vents, at shallow depth and low temperature. Almaden in Spain has been mined for it for two thousand years.
- Chiefly from
- Almaden, SpainGuizhou and Hunan, ChinaIdrija, SloveniaCalifornia, United States
Why it is that colour
The compound itself. Mercury sulfide is intensely red, which is exactly why it was the most important red pigment in the world for two thousand years.
Safety
This is mercury sulfide, and it is the entry that most justifies this field existing. Cinnabar is soft, it abrades on handling, and mercury is a potent neurotoxin. It should not be carried loose in a pocket, should never be powdered, should never be heated even slightly — heating releases mercury vapour, which is the truly dangerous route — and must never go anywhere near water intended for drinking or near the mouth. It is nonetheless sold routinely as tumbled stones and jewellery, and it is used in some traditional Chinese preparations, where mercury poisoning from it is documented.
Where it comes from
Chinese material dominates the specimen market. Almaden closed in 2002 after two millennia; it is now a UNESCO site. Mercury mining has been curtailed worldwide by the Minamata Convention, which entered force in 2017.
Historical use
The source of vermilion, the most brilliant red available to painters before synthetic pigments, used from Pompeii through to the Renaissance. Ground and purified cinnabar is the red of Chinese lacquer and of imperial seal paste. The tomb of the first Qin emperor is described by Sima Qian as containing rivers of mercury, and soil surveys of the mound have found anomalously high mercury.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Genuinely ancient and genuinely widespread: cinnabar was used as body paint and burial pigment from the Neolithic, in Anatolia, Iberia, China and Mesoamerica independently. In Chinese alchemy it was central to the pursuit of immortality, and several emperors are thought to have died of mercury poisoning from elixirs based on it. Its modern crystal-trade meanings are recent and, given the above, unfortunate.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Worth knowing
Chinese alchemy's fascination with cinnabar has an internal logic that is worth understanding rather than mocking. Heat cinnabar and it gives up liquid mercury; recombine mercury with sulfur and you get cinnabar back. A substance that could be destroyed and restored, changing between a red solid and a living metal, looked exactly like a model of death and return — and therefore like a candidate for conferring the same property on a person.
It killed a great many people, including, in all probability, several emperors. The Jiajing Emperor in the sixteenth century is a well-documented case.
That history is the reason to be blunt on a page like this. Cinnabar is genuinely beautiful, it is cheap, it is widely sold, and it is mercury.
Identity checked against IMA-CNMNC master list, June 2025.