Thread: Radioactivity of natural stones

Shale is naturally radioactive.
Sand and limestone are not.


I do not know if shale exposure or ingestion is hazardous.

Originally Posted by rolodave

Shale is naturally radioactive.
Sand and limestone are not.


I do not know if shale exposure or ingestion is hazardous.

Depends on the particular formation the shale came from. The Marcellus Shale found back east through West Virginia is well known to be Radioactive.

The problem isn't so much handling a chunk of the stuff it's when it's bought up as overburden (waste rock) and it's concentrated in piles or thrown into rivers where it breaks down.

I know a couple of people that work in nuclear power plants.

I wonder if I could ask them to carry my hones to work in their lunch box?

From what I understand they have some pretty sensitive sensors!

I've been told that walking down the salt isle in a grocery store with a geiger counter is enlightening.

When I was a home builder in Kansas City, we has a few basements that we had to put low flow air exchangers in due to Radon build up.

Here is a publication on natural background radioactivity and cancer. It is full of arithmetics that I do not understand but the authors conclusion is that natural background radiation is not harmful.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4674188/

Interesting meta-analysis, though the studies somewhat contradict each other. It would be cool if we could naturally develop radiation resistance, like the dark skin color for the Ultraviolet light.
I'm not afraid of natural radiation, but the presence of radioactive minerals in the stones, as if they happen to be present in the stone deposits, or even as inclusions that look like iron salts. Thorium salts are yellow, from a few I have seen (it could be impurities or some specific salt) as well as some Uranium salts.

Thinking about the fluorescent paint above I feel stupid for not thinking it sooner;
@Maladroit or anyone who knows about it (and anyone else who wants to say something, naturally), can I use some mineral/salt that's fluorescent under ionizing radiation to see if it glows in the dark after "spending some time" with something that could be radioactive? Fluorite, or maybe Lithium fluoride? I don't know which ones would work, or how much radiation would they need.

I too am a former radiation protection person (tech then later engineer), retired after 35 years at a university and National Lab.

Most natural materials, stone included, contain traces of uranium and thorium. I’ve never seen an analysis of most hone materials, but Alex Gilmore once sent me an analysis of Japanese natural stones, and they’re (unsurprisingly) about 86% silica, 6% iron, and the rest other trace elements. Being in the profession that I was, I looked for radioactive elements and there were none listed though no doubt some tiny traces are present. Out of curiosity I also looked for other problem children like heavy metals that could be a problem for miners/processors but saw none of them either.

Hones by their nature have to be mostly silica to function (except coticules), so there’s not a lot of ‘room’ left for much else, though a few percent of uranium/thorium could be detected with a simple geiger counter.

Radon is a noble gas with a half-life of about 3 hours. Being a noble gas, it does not accumulate in our bodies or undergo chemical reactions, therefore it is of no concern unless it is being replenished in our environment, for example from building materials. The radon daughters have an aggregate half life of about 45 minutes. However, the daughters can be accumulated or concentrated in our bodies, so if there is a source replenshing the radon, that is a concern. Hones however, simply aren’t large enough to provide a source of concern at trace uranium/thorium amounts.

Vasilis, if you have concerns, please send me all your best hones and I’ll have them tested for you and return them in a decade or two....

Cheers, Steve

Originally Posted by Steve56

Vasilis, if you have concerns, please send me all your best hones and I’ll have them tested for you and return them in a decade or two....

Cheers, Steve

If you opt for non-destructive testing as destructive testing will take less time of course.

Originally Posted by Kees

If you opt for non-destructive testing as destructive testing will take less time of course.

I think at least 10% to even 20% of the surface of the hone would have to be slowly abraded away to imitate "normal" use. The effect of slurry etc.

That would be a very time consuming task.