Is Pyromorphite Toxic?
Pyromorphite, Pb5(PO4)3Cl, is 76.38% lead by mass, worked. How UK lead law splits hazard from risk, and why a real specimen is not its formula. Not advice.
Pyromorphite is lead chlorophosphate, Pb5(PO4)3Cl, and 76.38% lead by mass, worked from standard atomic weights. The UK’s Control of Lead at Work Regulations 2002 separate hazard, an intrinsic property of lead, from risk, the likelihood of harm under conditions of use and exposure; the formula settles only the first. This page is not health advice.
In short
- What it is. The Handbook of Mineralogy pyromorphite sheet gives Pb5(PO4)3Cl, hexagonal, apatite group, hardness 3.5–4, brittle, density 7.04, with habits from long prisms to globular, reniform and botryoidal forms. Worked, lead is 1036.0 of a formula mass of 1356.36: 76.38%. The September 2026 IMA-CNMNC Master List writes the same formula, status G, 1813, Germany.
- The hazard–risk split. Control of Lead at Work Regulations 2002, regulation 2 defines hazard as the intrinsic property of lead which has the potential to cause harm, and risk as the likelihood that the potential for harm will be attained under the conditions of use and exposure. A formula with 76.38% lead answers the hazard question. It cannot answer the risk question, and this page does not.
- Documented failure: the formula is not the specimen. The IMA formula has no arsenic. The sheet’s own analysed specimen, from Wissen, Germany, prints As2O5 0.13%, which works out at 0.085% arsenic, and 75.50% lead rather than 76.38%. A label naming pyromorphite fixes the formula, not the composition of the piece.
- The lead apatite ladder. A script over the IMA list finds 5 rows written Pb5(XO4)3 plus one anion. Worked, they run from 69.61% lead in mimetite, which is also 15.10% arsenic, through 73.15% in vanadinite and 76.38% in pyromorphite, to 77.32% and 77.43% in fluorpyromorphite and hydroxylpyromorphite.
- Not advice. This page is not health, safety or legal advice. HSE’s page on when you are most at risk from lead says the body absorbs lead when you breathe in lead dust, fume or vapour, or swallow it. Workplace duties are a matter for HSE; exposure or symptoms for a clinician. The general site note is toxic minerals in a collection.
| Composition | Source | Pb (wt%) | As (wt%) | P or V (wt%) | U, Th or K in formula | Hazard wording on its sheet |
|---|---|---|---|---|---|---|
| Pyromorphite, ideal Pb5(PO4)3Cl | IMA (G, 1813, Germany); sheet column (2) | 76.38 | 0 | P 6.85 | None | None |
| Pyromorphite, Wissen, Germany | Sheet analysis (1) | 75.50 | 0.085 | P 7.03 | Not analysed | None |
| Fluorpyromorphite, Pb5(PO4)3F | IMA (A, 2021-120, Russia) | 77.32 | 0 | P 6.93 | None | No sheet consulted |
| Hydroxylpyromorphite, Pb5(PO4)3(OH) | IMA (A, 2017-075, USA) | 77.43 | 0 | P 6.95 | None | No sheet consulted |
| Vanadinite, Pb5(VO4)3Cl | IMA (G, 1838, Mexico) | 73.15 | 0 | V 10.79 | None | None |
| Mimetite, Pb5(AsO4)3Cl | IMA (G, 1832, Germany) | 69.61 | 15.10 | — | None | None |
Is pyromorphite toxic? What it is made of, worked
Pyromorphite is lead chlorophosphate, Pb5(PO4)3Cl, 76.38% lead by mass. Method: with Pb 207.2, P 30.974, O 15.999 and Cl 35.45, the formula mass is 1356.36, of which five lead atoms are 1036.0. Phosphorus is 6.85% and chlorine 2.61%. The Handbook of Mineralogy pyromorphite sheet prints the ideal composition as oxides, PbO 82.28, P2O5 15.70, Cl 2.61 less 0.59 for oxygen equivalent to chlorine, and the same arithmetic reproduces each figure. The species page, pyromorphite, has the identification; it is not repeated here.
What the sheet says, and does not. The sheet calls pyromorphite a secondary mineral in the oxidized zone of lead deposits, rarely a volcanic sublimate, and records hardness 3.5–4, a brittle tenacity, and habits that include acicular crystals and globular, reniform and botryoidal masses. It says the name is from the Greek for fire and form, as melted globules will recrystallize. A search of its text finds no toxic, poison, hazard or danger. The Handbook is a descriptive reference; its silence is not a verdict either way.
Radioactive or UV reactive? Neither question is about toxicity, and both come up. The IMA formula contains no uranium, thorium or potassium, and the sheet prints no radioactivity; the method is on is my mineral radioactive. The sheet says pyromorphite may fluoresce yellow to orange under longwave and shortwave UV; the arsenate’s case is on is mimetite UV reactive.
Hazard or risk? How the UK lead regulations split the question
The hazard–risk split: UK lead law defines the two words separately, and “is pyromorphite toxic” is a hazard question that people usually mean as a risk question. Control of Lead at Work Regulations 2002, regulation 2 says “hazard” means the intrinsic property of lead which has the potential to cause harm to the health of a person. It says “risk”, in relation to the exposure of an employee to lead, means the likelihood that the potential for harm to the health of a person will be attained under the conditions of use and exposure and also the extent of that harm.
Applied to pyromorphite. The hazard half is settled by chemistry: the formula is 76.38% lead, and the regulation’s definition of lead includes any compounds of lead. The risk half turns on conditions of use and exposure, which are facts about what is done with a specimen and where, not about the mineral. The regulation does not assess them for a mineral, and this page does not either. The three-part reading of that definition of lead, and a map of what COSHH, EH40 and CLAW each say, are on is cerussite toxic and are not repeated here.
Why CLAW and not COSHH. COSHH 2002, regulation 5 says COSHH regulations 6 to 13 apply except where and to the extent that the Control of Lead at Work Regulations 2002 apply. CLAW’s occupational exposure limit for lead other than lead alkyls is 0.15 mg/m³ in air, assessed as the element lead, as quoted on the cerussite page. These are workplace provisions; this page does not translate them into anything about a specimen.
Does pyromorphite contain arsenic? The formula against the analysis
Documented failure: the formula is not the specimen. Pyromorphite’s IMA formula, Pb5(PO4)3Cl, has no arsenic. The one natural analysis on its sheet, from Wissen, Germany, prints PbO 81.33, P2O5 16.11, As2O5 0.13 and Cl 2.71. Converted, that is 75.50% lead, 7.03% phosphorus and 0.085% arsenic, about 850 parts per million; arsenic takes 0.50% of the phosphorus-plus-arsenic sites. The lead figure sits 0.88 points below the ideal 76.38%.
The lead apatite ladder. A script over the September 2026 IMA list for formulas written Pb5, three XO4 groups and one anion finds 5 rows. Worked: mimetite, Pb5(AsO4)3Cl, 69.61% lead and 15.10% arsenic; vanadinite, Pb5(VO4)3Cl, 73.15%; pyromorphite, 76.38%; fluorpyromorphite, Pb5(PO4)3F (A, 2021-120, Russia), 77.32%; and hydroxylpyromorphite, Pb5(PO4)3(OH) (A, 2017-075, USA), 77.43%. The five span 69.61% to 77.43% lead, 7.82 points; only mimetite has arsenic in its formula.
Why the label matters, and where it stops. The mimetite sheet says its name is from the Greek for an imitator, as it imitates pyromorphite, and the two share hardness 3.5–4 and white streak; the difficulty of telling them apart is worked on how to tell pyromorphite from mimetite. A green or yellow piece labelled pyromorphite is not shown by its label to be arsenic-free. Arsenic minerals are covered on is orpiment toxic; this page does not rank pyromorphite against mimetite, because none of the sources fetched here does.
What does HSE say about lead, and where should questions go?
HSE’s lead pages describe lead in general, at work; none mentions minerals or collections. HSE’s page on when you are most at risk from lead lists industrial processes that create lead dust, fume or vapour, such as smelting, paint removal and battery work, and says your body absorbs lead when you breathe in lead dust, fume or vapour, or swallow any lead. HSE’s page on health effects from exposure to lead says there is growing scientific evidence that employees’ health is at risk even where exposure is below the levels in CLAW, and lists observed effects that include changes in the blood which might lead to anaemia, effects on the nervous system and effects on the kidney.
What this page does not do. It gives no handling, storage, cleaning or heating method, and no statement that any amount, form or use of pyromorphite is safe. The sheet records that melted globules recrystallize; this page draws nothing from that. This page is not health, safety or legal advice.
Where to go. HSE for workplace duties under CLAW 2002; a clinician for any question about exposure or symptoms. The general site note is toxic minerals in a collection, and the other lead pages are is cerussite toxic and is galena toxic. Other hazard questions are indexed at the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.