Is cinnabar toxic
Cinnabar is mercury sulphide, HgS, 86.22% mercury by mass, hardness 2 to 2.5. The form changes the answer: solid, dust, heated or native mercury. Not advice.
Cinnabar is mercury sulphide, HgS, 86.22% mercury by mass, hardness 2 to 2.5, density 8.176. It contains a toxic element, and the US ATSDR says mercury's health effects depend on the amount and form, the route and the length of exposure. Heating cinnabar releases mercury vapour, which is how mercury has long been produced. This is not health advice.
In short
- Yes, cinnabar is mostly mercury. HgS is 86.22% mercury by mass, almost the same fraction as galena's 86.60% lead. The Handbook of Mineralogy calls it the most common ore of mercury world-wide; the reasoning for galena is on is galena toxic.
- Form decides, not the element. ATSDR says mercury's effects depend on the amount and form, route and length of exposure. For a collector that means four states: a solid specimen, dust from working it, a heated specimen, and droplets of native mercury, which the cinnabar sheet lists first among its associates.
- Heat is the state that changes the chemistry. geology.com says cinnabar has been heated in furnaces for thousands of years and the mercury escapes as a vapour. The US EPA says exposed elemental mercury can evaporate at room temperature into an invisible, odorless toxic vapour.
- HSE EH40 lists mercury and divalent inorganic compounds, measured as mercury, at 0.02 mg per cubic metre as an 8-hour limit, with no short-term limit. It does not name cinnabar or mercury sulphide. Quoted, not interpreted.
- Nothing on this page is health, safety or legal advice. EH40 and the COSHH Regulations 2002 govern workplaces; a concern about exposure belongs with a clinician. The general collection guidance is on toxic minerals in a collection.
| Species | Formula | Element by mass | Hardness | Density, measured | What decides, per its page |
|---|---|---|---|---|---|
| Cinnabar | HgS | 86.22% mercury | 2 to 2.5 | 8.176 | Form: solid, dust, heated, or with native mercury |
| Galena | PbS | 86.60% lead | 2.5 to 2.75 | 7.58 | Cubic cleavage sheds lead-bearing fragments |
| Realgar | AsS | 70.03% arsenic | 1.5 to 2 | 3.56 | Light turns it to powder without handling |
| Baryte | BaSO4 | 58.84% barium | 3 to 3.5 | 4.50 | Solubility: it barely dissolves |
Is cinnabar toxic? What it is, and 86.22% mercury, calculated
Cinnabar is mercury sulphide, HgS, and 86.22% of its mass is mercury. Method: with Hg 200.592 and S 32.06, HgS has a formula mass of 232.65, of which mercury is 200.59. The Handbook of Mineralogy sheet says essentially pure HgS, so the ideal figure is the practical one: a 10 g specimen of pure cinnabar holds 8.62 g of mercury. It is trimorphous with metacinnabar and hypercinnabar, both also HgS. The IMA-CNMNC list of minerals lists cinnabar as a grandfathered species.
This site's reference set contains no mercury mineral. Of the 176 Handbook sheets in it, searched by script after pdftotext -layout, none has Hg in its formula line and none uses the word mercury. Hg appears only as a minor or trace constituent in the chemistry fields of three: freibergite, gold and silver. Cinnabar is named on one, as an associate of stibnite. The cinnabar sheet was fetched for this page as a comparator and is counted in no survey figure.
Cinnabar is also very heavy. Its measured density, 8.176, is higher than galena's 7.58. Of the 173 sheets in the set that print a measured density, four print a higher one than cinnabar's: gold, silver, uraninite and copper. The word toxic appears on one sheet in the set, arsenolite's, and not on the cinnabar sheet: the Handbook describes minerals and does not rank hazards.
Is cinnabar toxic to touch? The four states where the answer changes
Cinnabar's hazard is set by the form the mercury is in, which is the boundary this page draws. The US ATSDR ToxFAQs for mercury says the health effects of mercury depend on the amount and form, the route and the length of exposure, and age. For a specimen that gives four states:
- Solid. An intact crystal or massive piece is mercury bound as sulphide. That is the low-exposure case the toxic minerals in a collection page describes: do not make dust, wash your hands.
- Dust. Hardness 2 to 2.5 and a perfect {10-10} cleavage mean cinnabar is soft and slightly sectile, and the sheet records a dull lustre in friable material. Carving, grinding or brushing turns the solid state into particles.
- Heated. The geology.com cinnabar article by Hobart M. King says cinnabar has been mined and heated in a furnace for thousands of years, and the mercury escapes as a vapor. Heating turns the sulphide into elemental mercury vapour, the form ATSDR associates with nervous-system effects in exposed workers.
- With native mercury. The sheet's association list begins with mercury, and geology.com says small droplets of liquid mercury are sometimes present on or near cinnabar. The US EPA basic information about mercury says exposed elemental mercury can evaporate at room temperature to become an invisible, odorless toxic vapor.
This site does not turn that into handling advice. The same three-state reasoning, solid, worked and friable, is on is malachite toxic; cinnabar adds a fourth state because of heat and native mercury. This is not health, safety or legal advice.
What HSE EH40 lists for mercury, quoted rather than interpreted
EH40 lists mercury and divalent inorganic compounds, including mercuric oxide and mercuric chloride, measured as mercury, at a long-term limit of 0.02 mg per cubic metre over 8 hours, with no short-term limit given. Its biological monitoring table gives a guidance value of 20 μmol mercury per mol creatinine in urine, on a random sample. The document does not mention cinnabar or mercury sulphide by name, and this page does not decide how its entry applies to a specimen. These are workplace limits under the COSHH Regulations 2002; they are quoted, not interpreted.
Cinnabar's company matters as well. The sheet lists realgar and stibnite among its associates, so a cinnabar specimen can carry arsenic and antimony sulphides; is realgar safe to handle covers the first, and the realgar species page the mineral. Barite is on the list too, and is baryte toxic explains why its barium behaves differently.
Localities the sheet names. It lists New Almaden and New Idria in California, Terlingua in Texas, Almadén in Spain, Idrija in Slovenia, and twinned crystals from the Tsar Tien mine, Hunan, China. Hazard pages are indexed at the collecting guides. Nothing here is offered for sale; the wanted list is the only commercial route.