Is Eudialyte Radioactive?
Eudialyte’s sheet prints no uranium, thorium or radioactivity; a 1961 Greenland study found fresh crystals weakly radioactive and altered ones more. Not advice.
Weakly, in the one measured study found. Eudialyte’s Handbook sheet prints no radioactivity and its two analyses list no uranium or thorium, but Buchwald and Sørensen (1961) counted 10–35 alpha tracks per cm² per hour on fresh Ilímaussaq eudialyte, against a background of about 1, and often 4000 or more on altered grains. This is not safety advice.
In short
- The sheet says nothing. A whole-text search of the Handbook of Mineralogy eudialyte sheet finds no radioactivity statement, and its two analyses, Kipawa Lake and Khibiny, print 20 constituents with no uranium or thorium. The same search finds Radioactive on the uraninite sheet, the positive control. Absence from an analysis is not a measurement of zero.
- A measurement exists. Buchwald and Sørensen 1961, Meddelelser om Grønland 162 laid nuclear emulsions on thin sections from the Ilímaussaq complex, Greenland, where eudialyte was first described. Fresh eudialyte in naujaite and the Kringlerne kakortokites formed one weakly radioactive group, 10–35 alpha tracks per cm² per hour; their background was about 1.
- The fresh-versus-altered ladder. In the same study, eudialyte of the lujavrites gave 50–2100, and pseudomorphs and secondary patches in altered eudialyte often 4000 or more. In one pegmatite, fresh eudialyte gave 25–50 while steenstrupine along its fractures gave 4000–9000. The state of the grain matters as much as the name.
- Documented failure. Alpha tracks per cm² per hour in an emulsion are not becquerels per gram, and the regulation’s values are in becquerels per gram. No source fetched for this page converts one into the other for eudialyte, so this page does not.
- Not advice. This is not health, safety or legal advice. The Ionising Radiations Regulations 2017 are enforced by HSE; personal questions go to HSE or a radiation protection adviser. The general site note is is my mineral radioactive.
| Material | Rock or setting | Alpha tracks per cm² per hour, as printed | Page |
|---|---|---|---|
| Emulsion background | - | About 1 | 8 |
| Fresh eudialyte | Naujaite, naujaite pegmatites, the three Kringlerne kakortokites | 10–35 | 9 |
| Fresh eudialyte | Eudialyte pegmatite, Qeqertaussaq | 25–50 | 12 |
| Eudialyte | Inclusions of deformed kakortokite in green lujavrite, Kangerdluarssuk | 60–550 | 11 |
| Eudialyte, anisotropic vs isotropic parts | One green lujavrite, Kangerdluarssuk | Ca. 100 vs 300 | 11 |
| Eudialyte | Lujavrites, the most radioactive eudialytes examined | 50–2100 | 11 |
| Black zones with katapleite in eudialyte | Eudialyte pegmatite, Qeqertaussaq | 800–1000 | 12 |
| Monazite along eudialyte fractures | Eudialyte pegmatite, Qeqertaussaq | 1100 | 12 |
| Steenstrupine along eudialyte fractures | Eudialyte pegmatite, Qeqertaussaq | 4000–9000 | 12 |
| Pseudomorphs and secondary patches in altered eudialyte | Lujavrites and naujaites | Often 4000 or more | 12 |
| Lovozerite, unaltered vs cloudy | Veins and lujavrites | 300–850 vs 750–2500 | 12 |
Is eudialyte radioactive? What the Handbook sheet prints
Nothing: the eudialyte sheet makes no radioactivity statement, and its analyses list no uranium or thorium. Method: a script searches the pdftotext text of the Handbook of Mineralogy eudialyte sheet for radioactiv, for the words uranium and thorium, and for the oxides UO2, UO3, U3O8 and ThO2. It finds none. The same search on the uraninite sheet finds Radioactive and UO2, so the search works. The two analyses print 20 constituents, from SiO2 50.35% and ZrO2 11.80% down to P2O5 and S, including RE2O3, rare-earth oxides, at 6.40% and 0.37%.
Printed-oxide check, and its limit. The analyses show what was reported, not what was sought; the sheet does not say whether uranium or thorium were looked for. The cached sheets of eudialyte’s associates, nepheline, microcline, aegirine, sodalite and titanite, also print no radioactivity statement and no uranium or thorium oxide. None of that is a measurement, which is why the next section matters.
The formula. The IMA-CNMNC Master List writes eudialyte Na15Ca6Fe3Zr3Si(Si25O73)(O,OH,H2O)3(Cl,OH)2: uranium and thorium are not part of the species, so any radioactivity comes from what a given crystal has taken up. The species facts are on eudialyte.
What was measured: the 1961 Ilímaussaq alpha counts
Fresh eudialyte was weakly radioactive; eudialyte in the youngest rocks, and altered eudialyte, much more so. Buchwald and Sørensen 1961, Meddelelser om Grønland 162 examined 94 nuclear preparations from the Ilímaussaq complex, the area Johnsen et al. 2003 give as eudialyte’s first description. Their method: a 25 µm alpha-sensitive emulsion held against an uncovered thin section, usually for 230 to 350 hours, after which tracks over each mineral were counted and expressed as alpha tracks per cm² per hour. They give the background as about 1 and the counting uncertainty as probably about ±5%.
The fresh-versus-altered ladder. Eudialyte of naujaite, naujaite pegmatites and the three types of Kringlerne kakortokite formed one weakly radioactive group with 10–35. Eudialyte from inclusions of deformed kakortokite in green lujavrite gave 60–550, and the eudialytes of the lujavrites were the most radioactive examined, 50–2100. In their abstract: the eudialyte is very weakly radioactive in the naujaite, naujaite pegmatites and the kakortokites, more radioactive in the lujavrites, and the altered eudialyte may be strongly radioactive.
Documented failure: what the ladder cannot tell a collector. These are counts over grains in thin sections of rock from one complex, measured in 1960 or earlier. They are not readings of a hand specimen, they cover none of the sheet’s other localities, and the unit is not the one the regulations use. The table above sets out every figure quoted, as printed.
Why altered eudialyte reads higher
The 1961 authors attribute it to alteration products taking up radioactive elements. They list eudialyte’s alteration products as katapleite, lovozerite, neptunite, monazite, britholite, colourless mica, schizolite, analcime, aegirine, iron oxides and unidentified dust and pigmentation, and say the pseudomorphs and secondary patches are generally more strongly radioactive than the unaltered mineral, often 4000 or more. In the Qeqertaussaq pegmatite, fresh eudialyte gave 25–50, black zones with katapleite 800–1000, and steenstrupine and monazite in the fractures 4000–9000 and 1100. Their conclusion: the alteration products of the eudialyte may adsorb some of the migrating radioactive elements released during hydrothermal alteration.
The rock, not the mineral. The same paper describes the lujavrite, the youngest nepheline syenite of the complex, as averaging 100–200 ppm uranium and three to four times that amount of thorium, and names eudialyte, steenstrupine, monazite, britholite and thorite (with a question mark) as its radioactive minerals. That is a rock figure; it is not the uranium content of eudialyte, and no source fetched here gives one.
Other pages. Uranium minerals, where uranium is in the formula, are on is torbernite radioactive and is uraninite the same as uranium; potassium-40 in feldspar is on is amazonite radioactive. Their methods are not repeated here.
What UK regulation says, quoted, and who to ask
The regulations define terms; they do not name minerals. regulation 2 of the Ionising Radiations Regulations 2017 says a radioactive substance means any substance which contains one or more radionuclides whose activity cannot be disregarded for the purposes of radiation protection, and defines practice to include the handling, use, storage, holding or transport of radioactive substances. Regulation 3 applies them to any practice and to certain work in radon atmospheres. Schedule 7, Part 2 tabulates naturally occurring radionuclides in solid materials that are not processed for their radioactive, fissile or fertile properties, and gives U-238 sec and Th-232 sec a concentration of 1 Bq/g for notification. As the previous sections say, no figure for eudialyte in that unit was found.
Who advises. Regulation 14 requires every employer engaged in work with ionising radiation to consult suitable radiation protection advisers as necessary. HSE’s ionising radiation legal-base page says IRR17 also applies to work with natural radiation, including work in which people are exposed to naturally occurring radon gas and its decay products. These are workplace rules, quoted rather than interpreted; whether they touch a private collection is a question for HSE.
Where to go. This is not health, safety or legal advice. This page gives no dose figure and no handling or storage instruction; for anything personal ask HSE or a qualified radiation protection adviser. The site’s general pages are is my mineral radioactive and how to store radioactive mineral specimens; hazard pages are indexed at the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.