Answer to Question #15392 Submitted to "Ask the Experts"

I collect rocks and fossils as a hobby. I sometimes cut and slice the rocks or fossils using a rock saw. Cutting rocks can generate a lot of dust. As I understand, even accidental inhaling of dust from the rocks can be dangerous if the rocks emit alpha particles. I am trying to purchase a handheld survey meter. I learned that except high priced models, most models (available to the general public from online shopping) only detect beta and gamma particles. So, my question is if the survey meter doesn't detect beta or gamma particles at a concerning level from the rocks or fossils such as petrified wood, is it likely that they do not emit alpha particles? I have no clue and I wish I had studied a nuclear science in college. Thank you.

I really love your question. You've clearly done your research but just need a little extra help!

The radioactive materials we would expect in fossils (or pretty much any rocks) are naturally occurring radioactive materials (NORM). You are right, they will certainly be alpha emitting. That said, the quantity of the radioactive material in these sources is so low I do not believe you will be able to detect it compared to background radiation unless you use extremely sensitive instruments. If you are just curious, a nearby university may be willing to analyze one for you (I'm in the southeast and would be happy to scan one). 

A second answer to this question is that it is pretty rare for any radionuclide to be a pure alpha emitter (that is, only emitting alphas and not gammas or betas as well). This is particularly true in the NORM elements where one radionuclide decays to another which decays to another and so on. So, a decent beta gamma detector will very likely still answer your question as to if what you are cutting is elevated. I've not tested these but seen some around $50 online with really good reviews. 

A third answer to your question is that a thin-windowed GM will still detect alpha particles. You can find old ones on online at relatively low prices and if you want to be positive, Ludlum makes plastic ones (last time I bought one for our lab was around $750 but the price has likely increased over the past few years).

A final comment from my safety side is to understand that alpha particles cannot harm while external to your body, as they will not even penetrate skin. As you've mentioned, with cutting any particulates, inhalation is a concern so please consider using a mask and glasses to keep the material from getting inside your body. Radioactive or not, these dusts can irritate your lungs and cause damage.

I hope this helps, but don't hesitate to reach out if you have any follow-up questions. 

Charles Wilson IV, PhD, CHP