Is celestite radioactive?
No, by composition: celestite, the mineral species celestine, is Sr(SO4), and natural strontium is four stable isotopes. Strontium-90 is man-made, by fission.
No, by composition. Celestite, the IMA’s celestine, is strontium sulphate, Sr(SO4), with no uranium, thorium or potassium, and its Handbook sheet records no radioactivity. Natural strontium is four stable isotopes, 84Sr, 86Sr, 87Sr and 88Sr (ATSDR). Strontium-90 is a man-made radioactive isotope, produced by nuclear fission (EPA). This is not safety advice.
In short
- The formula and the sheet. The September 2026 IMA-CNMNC Master List writes celestine as Sr(SO4), status A, 1967 s.p., USA; the Handbook of Mineralogy sheet writes SrSO4. A script finds strontium, sulphur and oxygen, and no uranium, thorium or potassium. The sheet has no radioactivity line, where the torbernite and uraninite sheets, the positive controls, both print Radioactive. Its one analysis, from Djebel Kebbouch, Tunisia, reports SO3, CaO and SrO and nothing else.
- The four-isotope ledger. The CIAAW strontium page gives natural strontium as 84Sr 0.56%, 86Sr 9.86%, 87Sr 7.00% and 88Sr 82.58% of atoms, and ATSDR ToxFAQs for strontium calls those four the stable isotopes. A 20.00 g celestine is 47.70% strontium, 9.54 g: worked by mass, 0.051 g of 84Sr, 0.922 g of 86Sr, 0.662 g of 87Sr and 7.905 g of 88Sr. None of it is a radioactive strontium isotope.
- Strontium-90 is not natural strontium. The US EPA, Radionuclide Basics: Strontium-90 page says naturally occurring strontium is not radioactive and that the most common man-made radioactive form, strontium-90, is produced through nuclear fission; ATSDR says 90Sr is formed in nuclear reactors or during the explosion of nuclear weapons. Both give a half-life of 29 years, and both describe it as man-made.
- Documented limit: the radium question is open. The sheet says celestine forms a series with barite, and USGS Fact Sheet FS-142-99 says barite readily incorporates radium, which is why barite pipe scale can be radioactive (worked on is baryte radioactive). No source fetched for this page measures radium in celestine, so this page gives no figure and does not transfer the baryte finding. 87Sr comes from radioactive 87Rb decay (CIAAW), but is itself stable.
- Not advice. No dose, count rate or activity is given here. A celestine that glows under UV is emitting light, not radiation; see is celestite UV reactive. The general method for a collection is is my mineral radioactive; questions about a specimen, a workplace or a person go to HSE or a radiation protection adviser.
| Strontium isotope | Atomic mass, Da (CIAAW) | Share of natural strontium atoms (CIAAW) | What the sources say | Grams in 20.00 g of celestine, worked | Atoms, worked |
|---|---|---|---|---|---|
| 84Sr | 83.913 | 0.56% | One of four stable isotopes (ATSDR) | 0.051 g | 3.7 × 10²⁰ |
| 86Sr | 85.909 | 9.86% | Stable (ATSDR) | 0.922 g | 6.5 × 10²¹ |
| 87Sr | 86.909 | 7.00% | Stable (ATSDR); the product isotope of radioactive 87Rb decay (CIAAW) | 0.662 g | 4.6 × 10²¹ |
| 88Sr | 87.906 | 82.58% | Stable (ATSDR) | 7.905 g | 5.4 × 10²² |
| 90Sr | — | Not in the natural list | Radioactive, beta, half-life 29 years; man-made by nuclear fission (EPA) | 0 by composition | — |
| Uranium, thorium, potassium | — | — | Not in Sr(SO4) (IMA formula, by script); not in the sheet’s analysis | 0 by formula | — |
Is celestite radioactive? What the formula and the sheet say
No radioactive element is in the formula. Celestite is the common name; the IMA list calls the species celestine and writes Sr(SO4), status A, 1967 s.p., country USA. The Handbook of Mineralogy celestine sheet writes SrSO4. On standard atomic weights that is 47.70% strontium, 17.45% sulphur and 34.84% oxygen. A script reading the element symbols finds no uranium, thorium or potassium.
The sheet is silent, and silence is checked. A search of the celestine sheet for radioact and metamict finds nothing; the same search on the torbernite and uraninite sheets finds Radioactive on each. The sheet’s analysis, from Djebel Kebbouch, Tunisia, reads SO3 43.40, CaO 0.40 and SrO 56.20, which works out at 47.52% strontium. Its identification numbers, hardness 3 to 3.5 and density 3.97, are used on how to identify celestite and celestine, and are not repeated as this page’s check.
Is strontium radioactive? The four-isotope ledger
Natural strontium is four stable isotopes. The CIAAW, the IUPAC commission on isotopic abundances and atomic weights, lists strontium’s natural isotopes as 84, 86, 87 and 88, with amount fractions 0.0056, 0.0986, 0.0700 and 0.8258 and a standard atomic weight of 87.62. ATSDR states that strontium in the environment exists in four stable isotopes, the same four, and that naturally occurring strontium is not radioactive.
The ledger, worked. Converting those amount fractions to mass with each isotope’s atomic mass, a 20.00 g celestine’s 9.54 g of strontium is 7.905 g of 88Sr, 0.922 g of 86Sr, 0.662 g of 87Sr and 0.051 g of 84Sr, about 6.6 × 10²² strontium atoms in all. Every gram is a stable isotope. The CIAAW notes one complication: 87Sr is the product isotope of radioactive 87Rb decay, and its abundance varies naturally. That variation is the basis of Rb–Sr dating; the strontium produced is stable.
What about strontium-90?
A man-made isotope. The US EPA’s strontium-90 page says the most common man-made radioactive form of strontium is strontium-90, produced through nuclear fission, a beta emitter with a half-life of 29 years, found in the environment from nuclear testing in the 1950s and 1960s and in nuclear reactor waste. ATSDR says the same: 90Sr is formed in nuclear reactors or during the explosion of nuclear weapons. ATSDR describes strontium as a naturally occurring element found in rocks, soil, dust, coal and oil, and calls that natural strontium stable.
What that means for celestine. Its strontium is natural strontium, which the CIAAW lists without a mass-90 isotope. This page says nothing about strontium-90’s health effects, which belong to the EPA and ATSDR pages and to a clinician; it is not health advice.
Can celestite carry radium, like baryte?
Open, on the sources fetched. The celestine sheet says it forms a series with barite and puts it in the barite group. The USGS fact sheet FS-142-99 says barite is known to readily incorporate radium in its structure and is the primary host of radioactive oil-field scale. That finding, and its radium ladder, are on is baryte radioactive. The fact sheet does not mention celestine or strontium, and no source fetched for this page measures radium in a celestine specimen, so no figure is given and the baryte result is not carried across.
What would answer it. A measurement of the specimen itself, which this page does not offer. The general guide for a collection is is my mineral radioactive, and storage is on how to store radioactive mineral specimens. The HSE ionising radiation legal base page says the main legal requirements enforced by HSE are the Ionising Radiation Regulations 2017 (IRR17). This is not health, safety or legal advice.
Why does celestite glow, and is it toxic?
The glow is light. Celestine fluoresces in the Fluorescent Mineral Society records worked on is celestite UV reactive, and fluorescence is a light effect, explained on fluorescent minerals explained. It is not evidence of radioactivity. Its brittleness and cleavage are on is celestite fragile, and whether it is a quartz on is celestite a quartz.
Chemistry is a separate question. Whether any mineral needs care for chemical reasons is routed to toxic minerals in a collection; this page gives no handling advice. Celestine’s series partner, baryte, and the strontium carbonate, strontianite, have their own pages; more in the collecting guides. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.