Is it safe to keep uranium and thorium minerals at home?

A few uranium and thorium specimens can be kept at home with care, but the National Park Service treats them as a real hazard and sets out how: handle them in latex or nitrile gloves, keep your distance, store them where radon gas cannot build up, ventilate that space to the outside, monitor for radon and label the cabinet (Conserve O Gram 11/10, September 2006) [1]. The bigger risk in a home is usually radon collecting in a closed cabinet, more than radiation from a single piece on a shelf. Federal licensing does not reach unrefined, unprocessed ore under the Nuclear Regulatory Commission's exemption, provided you do not refine or process it [2].

Which specimens are radioactive

COG 11/10 lists autunite, brannerite, carnotite, monazite, thorianite and uraninite as common radioactive minerals, with most of the radioactivity coming from uranium-238 or thorium-232 [1]. The NPS storage note adds gummite and pitchblende to the specimens it flags [3]. Two warnings from the same sources catch collectors out:

• Fossils can be radioactive. Uranium minerals "may become deposited in both bone and wood fossils," so a dinosaur bone fragment or a piece of petrified wood from a uranium district may be radioactive with nothing on its label to say so [1].
• You cannot tell by looking. If you cannot identify a mineral, COG 11/10 suggests a university geology department, which may also lend a Geiger counter, "the best way to determine whether a mineral specimen is radioactive and the level of radiation" [1]. Without a counter, it describes a low-cost test from Blount (1990): set the specimen on a light-proof packet of black-and-white film, then develop the film and see whether it has fogged [1].

Some uranium minerals fluoresce under ultraviolet light, which makes them popular with fluorescent collectors. Fluorescence is not a test for radioactivity; the fluorescent minerals and UV lamps page explains its limits as a clue.

What the radiation is, and what stops it

COG 11/10 notes that exposure drops sharply with distance, following an inverse square relationship [1]. In practice that means doubling your distance from a specimen cuts the dose from it to about a quarter. It is why the most useful single habit is not to keep radioactive pieces where people sit, sleep or work for hours.

For shielding specimens on display, the NPS says "it's best to make it out of wood and/or acrylic" (Plexiglas) [1].

Radon: the problem in a closed cabinet

Some uranium-series minerals give off radon, a colorless, odorless gas that emits alpha particles; inside the lung, those short-range particles can cause cancer [1]. COG 11/10 gives the facts that matter for storage [1]:

• Radon is heavier than air and settles in the low parts of cabinets and rooms.
• Its half-life is 3.8 days. In a closed cabinet it reaches equilibrium, which means it builds to a steady concentration rather than escaping.
• Radon's decay products are solid particles that attach to dust and can be inhaled. Their half-lives range from fractions of a second to under 30 minutes.

Put those together and you have the reason a drawer of uranium minerals should not be opened with your face over it. Every time you open a closed cabinet that has sat for days, you release the gas and dust that have accumulated inside.

Setting up storage at home

The NPS gives its recommendations for museum storage rooms. Applied to a home collection, they become a short checklist.

1. Choose the space. COG 11/10 calls for rooms holding radon-producing minerals to have good ventilation to the outside, without recirculated air [1]. At home, that rules out a bedroom closet or a cabinet in a living room. A ventilated garage, shed or workroom with an outside air path is closer to what the NPS describes.
2. Store low and away. Because radon settles, keep the cabinet where you are not working at floor level beside it, and away from heating returns that would pull its air into the house.
3. Monitor. The NPS says to install a radon monitor and check it regularly [1].
4. Label the cabinet. COG 11/10 says to label cabinets holding radioactive minerals with appropriate signage, note them in emergency planning documents and brief first responders [1]. At home, keep a list with your collection records saying what the radioactive pieces are and where they sit, so a family member or executor knows.
5. Box each piece. A closed box keeps fragments and dust with the specimen. Label it with the species and "radioactive."
6. Keep the number down. A single autunite thumbnail is a different proposition from a drawer of uraninite. If your radioactive holdings keep growing, take that as the signal to get professional advice (below).

Handling: the NPS standard precautions

COG 11/10 lists them as standard precautions [1]:

• Wear latex or nitrile gloves when handling radioactive specimens.
• Wash your hands after handling them.
• Keep radioactive dust off yourself and out of work areas.
• Wear a lab coat or other protective outer layer.

Never cut, grind, crush or tumble a radioactive specimen. That turns an external hazard into dust you can breathe, and under federal rules it may also change your legal position (see the next section).

What federal regulation says

The Nuclear Regulatory Commission licenses "source material," which includes uranium and thorium. Two exemptions in 10 CFR 40.13, as the regulation reads in the electronic Code of Federal Regulations (up to date as of October 19, 2026), are the ones a collector meets [2]:

• 40.13(a) exempts source material in a chemical mixture, compound, solution or alloy in which it is "less than one-twentieth of 1 percent (0.05 percent)" by weight [2].
• 40.13(b) exempts anyone who receives, possesses, uses or transfers "unrefined and unprocessed ore containing source material," on the condition that, unless a specific license authorizes it, the person "shall not refine or process such ore" [2].

A natural mineral specimen kept as it came from the ground fits most naturally under 40.13(b). The regulation does not mention mineral specimens by name, so treat this as what the text says rather than a ruling on your collection, and confirm with the NRC or your state's radiation control agency if your situation is unusual. An exemption from licensing is not a statement that a specimen is safe; the NPS precautions above apply either way.

Shipping is a separate question with separate rules. The USPS and Department of Transportation provisions are set out on shipping radioactive, asbestos and mercury minerals. Do not mail a radioactive specimen on the strength of the NRC exemption.

When a collection needs professional advice

COG 11/10 points museums to their health and safety program and to how other institutions handle these minerals [1]. For a private owner, get advice from your state radiation control agency or a health physicist when:

• you inherit or buy an old collection with unknown uranium or thorium pieces (common in collections assembled during the uranium boom; see buying a collection);
• the radioactive specimens are many, large or stored in a closed room in the house;
• a specimen has crumbled or been cut, so there is loose radioactive dust;
• you want to get rid of a piece. Disposal routes are on getting rid of hazardous specimens.

Before a radioactive piece leaves your house

Selling, trading or mailing a uranium mineral is where most collectors get into trouble, because postal and carrier rules are stricter than the NRC exemption. Read shipping radioactive, asbestos and mercury minerals before you list or post one.

References

1. National Park Service, Conserve O Gram 11/10, *Radioactive Minerals*, Greg McDonald, September 2006. https://nps.gov/subjects/museums/upload/11-10_508.pdf
2. U.S. Nuclear Regulatory Commission, 10 CFR 40.13, *Unimportant quantities of source material*, eCFR, up to date as of October 19, 2026. https://www.ecfr.gov/current/title-10/chapter-I/part-40/subject-group-ECFR4f6487a7eccf876/section-40.13
3. National Park Service, Conserve O Gram 11/2, *Storage Concerns for Geological Collections*, Kathy Hall, April 1998. https://www.nps.gov/subjects/museums/upload/11-02_508.pdf