Is Uraninite the Same as Uranium?
No. Uranium is element 92, a metal of density 19.1; uraninite is the mineral species UO2, hardness 5 to 6 and 88.15% uranium. Which word a specimen label needs.
No. Uranium is the element, atomic number 92, a radioactive silvery metal of density 19.1 (Royal Society of Chemistry). Uraninite is a mineral, UO2 on the September 2026 IMA list: uranium oxide, hardness 5 to 6, density 10.63 to 10.95. Ideal UO2 is 88.15% uranium by mass; the Handbook’s Placer de Guadalupe analysis works out at 80.67%.
In short
- Two different things. The Royal Society of Chemistry periodic table gives uranium as element 92, relative atomic mass 238.029, density 19.1, an actinide and a radioactive, silvery metal. The September 2026 IMA-CNMNC Master List lists uraninite as UO2, grandfathered, 1845, Czech Republic. The Handbook of Mineralogy sheet names it for the uranium in its composition.
- The one-row test. A script finds 41 IMA rows written as a single element symbol, from aluminium to zinc, and none is U: the list carries no native uranium. It finds exactly one row of uranium and oxygen alone, uraninite, by a field scan and a token scan that agree.
- The uranium-share ledger. Metal 100%; ideal UO2 88.15%; U3O8, the RSC’s pitchblende formula, 84.80%; UO3 83.22%; the sheet’s Placer de Guadalupe uraninite 80.67%; its microprobe uraninite with 14.3% ThO2 and 13.9% PbO, 60.80%. A uraninite specimen is uranium oxide, not the element.
- Documented failure: pitchblende. The word has no IMA line. The RSC calls pitchblende U3O8 while the IMA and the Handbook write uraninite UO2, and USGS OFR 99-529 keeps separate pitchblende and uraninite rows. On a label it does not name one species formula.
| Name | What it is | Formula or analysis | Uranium by mass | Density | 20.00 g in water | IMA row |
|---|---|---|---|---|---|---|
| Uranium | Chemical element 92 (RSC) | U | 100% | 19.1 | 18.95 g | None: 0 of 41 single-element rows |
| Uraninite, ideal | Mineral species | UO2 | 88.15% | 10.63–10.95 (sheet, measured) | 18.12–18.17 g | G, 1845, Czech Republic |
| Pitchblende, as the RSC writes it | Name in use; no IMA line | U3O8 (RSC) | 84.80% | n.p. | — | None: 0 lines |
| UO3 component | The U6+ oxide reported in the sheet’s analyses | UO3 | 83.22% | — | — | Not a row as written |
| Uraninite, Placer de Guadalupe, Chihuahua | Sheet analysis (1) | UO2 70.09, UO3 22.69, ThO2 0.20, PbO 0.40 wt% | 80.67% | — | — | Uraninite |
| Uraninite, locality not stated | Sheet analysis (2), microprobe | UO2 50.0, UO3 20.1, ThO2 14.3, PbO 13.9 wt% | 60.80% (Th 12.57%, Pb 12.90%) | — | — | Uraninite: U 0.66 to Th 0.15 cations |
| Uraninite, oxidised | The sheet’s lower density limit | n.p. | n.p. | As low as 6.5 | 16.92 g | Uraninite |
| Thorianite | Series partner (both sheets) | ThO2 | 0% (Th 87.88%) | 9.7–9.8 | 17.94–17.96 g | G, 1904, Sri Lanka |
Is uraninite the same as uranium? Three criteria
Uraninite is not uranium: one is a mineral species on the IMA list, the other a chemical element that the mineral contains. Three criteria decide which word belongs where. Is it on the IMA list? Uraninite is, as UO2, status G, 1845, Czech Republic; uranium is not. Is it a compound with a crystal structure found in nature, or a single element? The Handbook of Mineralogy uraninite sheet gives uraninite as cubic, point group 4/m −3 2/m, uranium oxide; the Royal Society of Chemistry periodic table gives uranium as element 92, an actinide metal. And what does the label have to identify: a specimen, or an element in it?
The one-row test. The IMA list does include native elements: a script finds 41 rows written as a single element symbol, among them gold, silver, copper, arsenic, bismuth and lead, and diamond and graphite for carbon. None is U. The same script finds one row whose formula is uranium and oxygen alone, uraninite, and one of thorium and oxygen alone, thorianite. The species-or-not question for other names is on is quartz a mineral and is gold a mineral; the general distinction is on crystal vs mineral.
The order the names arrived in. The RSC says the mineral pitchblende turned up in silver mines and that Martin Heinrich Klaproth of Berlin investigated it in 1789 and realised it was the oxide of a new element. The IMA list’s first reference for uraninite is dated 1845, and the sheet derives the name from uranium. The mineral came first, then the element, then the species name.
How much uranium is in uraninite? The uranium-share ledger
Ideal uraninite, UO2, is 88.15% uranium by mass; the two analyses on its Handbook sheet work out at 80.67% and 60.80%. The figure for UO2 is 238.02891 divided by 270.027, on standard atomic weights. The Placer de Guadalupe, Chihuahua, analysis reports 70.09% UO2 and 22.69% UO3, so three-quarters of its uranium atoms, 76.6%, are U4+. The microprobe analysis, locality not stated, carries 14.3% ThO2 and 13.9% PbO; its uranium falls to 60.80%, with thorium 12.57% and lead 12.90%.
Still uraninite. The sheet prints the second analysis as (U4+0.48U6+0.18Pb0.16Th0.15Ca0.01Ce0.01)Σ=0.99O2.01: uranium 0.66 of 0.99 cations, thorium 0.15. Uraninite forms a series with thorianite on both sheets, and Nickel and Grice 1998 define a species by the predominant atom on a site, so the name stays uraninite.
Density follows. The sheet gives 10.63 to 10.95 measured, decreasing markedly with oxidation to as low as 6.5. A 20.00 g piece reads 18.12 to 18.17 g in water across the measured range and 16.92 g at 6.5; uranium metal at the RSC’s 19.1 would read 18.95 g. Method: how to measure specific gravity at home. The uranium-by-mass figures for torbernite and autunite are on is torbernite radioactive and is autunite dangerous and are not repeated here.
Is pitchblende the same as uraninite?
Pitchblende is a name in use, not an IMA species: the September 2026 list has no line containing it, and the sources fetched here do not give it one formula. The RSC page writes that uranium occurs in several minerals such as “uranite (pitchblende)”, and elsewhere calls pitchblende “uranium oxide, U3O8”. The IMA list and the Handbook write uraninite UO2. USGS Open-File Report 99-529, Table 1 lists Pitchblende, 2 samples, and Uraninite, 4 samples, as separate rows.
Who each word is wrong for. Uranium is wrong on a specimen label: it names the element, and no mineral specimen is the element. Pitchblende is wrong where a species is wanted: no IMA line, and the sources disagree on its formula. Uraninite is the species name for UO2 and the right label word for a specimen that is uranium oxide, with thorianite for a thorium-dominant one. Labelling practice is on how to label and catalogue a mineral collection.
Documented failure: the formula a reader brings. A reader who learned pitchblende as U3O8 will expect 84.80% uranium; ideal UO2 gives 88.15%, and the sheet’s real analyses 80.67% and 60.80%. None of the three numbers is the answer for every specimen, which is why the ledger above prints all of them.
Where is uraninite found, and is it radioactive?
The uraninite sheet’s Distribution field calls it widespread. It names Jáchymov (Joachimsthal) and Horní Slavkov, Czech Republic; Johanngeorgenstadt, Schneeberg and Annaberg, Saxony, and Wölsendorf and Hagendorf, Bavaria; many mines in Cornwall; large crystals from the Sierra Albarrana, Córdoba, Spain; Wilberforce, Ontario, and Great Bear Lake; Standpipe Hill, Topsham, Maine, for fine crystals; Spruce Pine, North Carolina; Shinkolobwe and Kalongwe in the Katanga Copperbelt; and Morogoro, Tanzania. No USGS, BGS or IAEA text was fetched for this page, so it makes no ore claim.
Radioactivity. The sheet prints “Radioactive.” and nothing more on the subject; for what that means in a collection see is my mineral radioactive and how to store radioactive mineral specimens. This page is not health or safety advice and gives no dose, activity or storage figure. Other naming questions are in the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.