Is wulfenite radioactive?
Not by its formula. Wulfenite is Pb(MoO4), with no uranium, thorium or potassium, and its sheet prints none. Yet 6 of 23 IMA molybdate rows carry uranium.
Not by its formula. The IMA list writes wulfenite Pb(MoO4): lead, molybdenum and oxygen, no uranium, thorium or potassium, and its Handbook sheet, hardness 2.75–3, prints no radioactivity. Molybdate is not the issue: 6 of the 23 IMA molybdate rows carry uranium, two of them yellow on their sheets, so the formula decides, not the colour.
In short
- The formula. The September 2026 IMA-CNMNC Master List writes Pb(MoO4), status G, 1845, Austria. A script lists its elements as lead, molybdenum and oxygen. Worked, it is 56.44% lead and 26.13% molybdenum; uranium, thorium and potassium are 0.
- The sheet. The Handbook of Mineralogy wulfenite sheet has no radioactivity line, and a search of it and of the sheets of its 9 mineral associates finds none; the torbernite and uraninite sheets, the positive controls, both print Radioactive. Its two analyses report MoO3, WO3 and PbO only.
- The molybdate screen. A script over the IMA list finds 23 rows with a (MoO4) group. Six contain uranium: calcurmolite, cousinite, moluranite, sedovite, tengchongite and umohoite, and all six sheets print Radioactive. Two contain thorium and one potassium. Wulfenite is one of 2 lead (MoO4) rows, with molybdofornacite; neither carries U, Th or K.
- Documented failure: colour and a silent sheet. Calcurmolite is deep honey-yellow to bright yellow and tengchongite yellow on their sheets, and both print Radioactive, so yellow does not clear a molybdate. In water a 20.00 g wulfenite reads 16.92–17.33 g against 15.00–15.71 g for the uranium molybdates with a density. And the thorium molybdate nuragheite’s sheet prints no Radioactive line at all.
- Not advice. No dose or activity figure is given here. The general guide is is my mineral radioactive; personal questions go to HSE or a radiation protection adviser. Wulfenite is a lead mineral: see toxic minerals in a collection.
| Species | IMA formula | U, Th or K in formula | Sheet prints Radioactive | Colour (sheet) | Density | 20.00 g in water |
|---|---|---|---|---|---|---|
| Wulfenite | Pb(MoO4) | None | No | Bright yellow, orange, red; gray, green, blue, brown, black | 6.5–7.5 | 16.92–17.33 g |
| Molybdofornacite | CuPb2(MoO4)(AsO4)(OH) | None | No | Light green to olive-green | n.d. | n.d. |
| Calcurmolite | (Ca1-xNax)2(UO2)3(MoO4)2(OH)6-x·nH2O | U | Yes | Deep honey-yellow, bright yellow | n.d. | n.d. |
| Tengchongite | Ca(UO2)6(MoO4OH)2O2(OH)4(H2O)4·5H2O | U | Yes | Yellow | 4.25 | 15.29 g |
| Umohoite | (UO2)(MoO4)(H2O)·H2O | U | Yes | Blue-black with dark green patches | 4.53–4.66 | 15.58–15.71 g |
| Sedovite | U4+(MoO4)2 | U | Yes | Brown to reddish brown | 4.2 | 15.24 g |
| Moluranite | H4U4+(UO2)3(MoO4)7·18H2O | U | Yes | Black, brown in thin fragments | About 4 | 15.00 g |
| Cousinite | MgU4+2(MoO4)2(OH)6·2H2O(?) | U (status Q) | Yes | Black | n.d. | n.d. |
| Nuragheite | Th(MoO4)2(H2O) | Th | No | Colorless | 5.147 calc. | 16.11 g (calc.) |
| Ichnusaite | Th(MoO4)2(H2O)2·H2O | Th | No sheet | — | — | — |
| Yunhaoite | K2(MoO4) | K | No sheet | — | — | — |
Is wulfenite radioactive? What the formula and the sheet say
Its formula contains no radioactive element of the kinds collectors meet: no uranium, no thorium, no potassium. The September 2026 IMA list writes wulfenite Pb(MoO4), status G, 1845, Austria; a script reads the elements as lead, molybdenum and oxygen. Worked on standard atomic weights, it is 56.44% lead, 26.13% molybdenum and 17.43% oxygen. The radioactivity of a potassium mineral, worked on is amazonite radioactive, does not arise here, because there is no potassium.
The sheet. The Handbook of Mineralogy wulfenite sheet gives tetragonal crystals, commonly square and flat tabular, hardness 2.75–3, density 6.5–7.5 measured and 6.88–7.48 calculated, and the note that individuals may be piezoelectric. A case-insensitive search for radioactiv finds nothing on it, nor on the sheets of the 9 minerals its association line names: cerussite, anglesite, smithsonite, hemimorphite, vanadinite, pyromorphite, mimetite, descloizite and plattnerite. The same search finds Radioactive on the torbernite and uraninite sheets.
The analyses. The sheet prints two. Oudida, Morocco, MoO3 38.87 and PbO 60.91, corresponding to Pb1.01Mo1.00O4.00. Chillago, Australia, MoO3 17.52, WO3 28.22 and PbO 54.25, corresponding to Pb1.00(Mo0.50W0.50)O4.00. The substitution recorded is tungsten for molybdenum, the element of stolzite, Pb(WO4) on the IMA list. Neither analysis lists uranium or thorium; an analysis reports what was measured, not everything that might be there.
Which molybdates are radioactive? The molybdate screen
Some molybdates are, and their formulas say so. A field scan of the September 2026 IMA list for formulas containing (MoO4), cross-checked against a raw line count of 23, finds 23 rows. Six contain uranium: calcurmolite, cousinite (status Q, questionable), moluranite, sedovite, tengchongite and umohoite. Two contain thorium, ichnusaite and nuragheite; one, yunhaoite, contains potassium. The other 14 contain none of the three, wulfenite and powellite, Ca(MoO4), among them.
What their sheets print. All six uranium (MoO4) sheets print Radioactive, and so does iriginite’s, a uranium–molybdenum mineral without a (MoO4) group in its IMA formula. Across all 97 IMA rows with molybdenum, 10 carry uranium. The screen is the same one a label check makes, applied to the formula: if U or Th is not in it, the species is not a uranium or thorium mineral. The label-first approach in general is on is my mineral radioactive; it is not repeated here.
Can a yellow molybdate be radioactive? The colour trap
Documented failure: yes, so colour cannot clear a specimen. Wulfenite’s sheet lists bright yellow, wax-yellow, yellow-orange and bright orange among its colours. The calcurmolite sheet gives deep honey-yellow and bright yellow; tengchongite’s, yellow; iriginite’s, canary-yellow. All three print Radioactive. A yellow tablet labelled only molybdate tells you nothing until the species is known.
Where the balance helps. Worked as 20 − 20/D, a 20.00 g wulfenite reads 16.92–17.33 g in water. The uranium molybdates with a printed density read lower: tengchongite 15.29 g, sedovite 15.24 g, umohoite 15.58–15.71 g, moluranite about 15.00 g, iriginite 15.28 g on its calculated density. The gap is more than 1.2 g. Calcurmolite and cousinite have no measured density, so the balance says nothing about them. Method: how to measure specific gravity at home.
Documented failure: the silent sheet. The thorium molybdate nuragheite, Th(MoO4)2·H2O on its sheet, colourless, has no Radioactive line, though thorium is in its formula. A sheet without the word is therefore not proof of no radioactivity; the formula is the stronger test, and it is the one wulfenite passes.
What this page does not say about wulfenite
No trace-element, isotope or dose claims. No source fetched for this page measures uranium or thorium traces in wulfenite, so none is asserted, and no activity or dose is calculated. Torbernite, which is a uranium mineral, is worked on is torbernite radioactive; a measured weakly radioactive species is on is eudialyte radioactive; and another non-uranium question is on is baryte radioactive. Storage questions for uranium minerals are on how to store radioactive mineral specimens.
Its UV question is separate. Wulfenite’s sheet prints no luminescence either; that is covered on is wulfenite UV reactive. The tungstate–molybdate family is on scheelite.
Not advice. This page is not health, safety or legal advice; personal questions go to HSE or a radiation protection adviser. Wulfenite is 56.44% lead by mass; lead is covered on toxic minerals in a collection and is galena toxic. Other guides are under the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.