I mean…is it possible to find a rock of Uranium lying around somewhere that would kill you eventually if you set it on your nightstand? Or does it take refining to make any mineral found naturally to make it dangerous? (I’m not including swallowing or otherwise getting the substance internally)
yes, there are naturally occuring concentrations of radioactive substances pre-refinement that can kill you. After all, x-rays were discovered by accident IIRC because of a rock that left a mark on a film. Or am I wrong about that? Anyway, besides that, it is yes, yes, yes.
Well, there’s some uranium mines in Africa where the concentration is so high that they’ve had natural chain reactions, which is certainly enough to kill. As to natural radioactives in normal concentrations, the question isn’t whether they can kill you, but how likely it is. A single gamma ray can, theoretically, cause cancer which ultimately kills you, but I’m not exactly worried about one or two photons here or there.
jmullany: X-rays were first discovered as emanations from cathode ray tubes, but it wasn’t long afterwards that it was found that pitchblende (uranium ore) produced them, too.
According to this site radon gas is a naturally occuring gas resulting from the decay of uranium in the earth’s crust. It is responsible for up to 40% of all lung cancer deaths in miners, and 10% of lung cancer deaths in the United States may be due to indoor exposure to radon.
You seem to be saying that uranium ore produces x-rays.
Out of curiosity, is this true? I thought there were enough safeguards that it took the cumulative damage from several gamma ray photons for cancer to develop.
BTW, those stats about radon are completeley made up.
They might be true. They might not.
But there’s no way to show probable cause and effect.
Well, everything produces radiation…it just happens to be in extremely low amounts. If you go by the logic that being hit by even a minimal amount of radiation will cause cancer, we’d all be dead at about 10 years of age.
By the way, gamma radiation is presented in the form of electromagnetic radiation, which I don’t think is the same as a photon. A photon is an actual packet of energy…electromagnetic radiation is just a wave. You might have gotten it confused with alpha or beta radiation, which are particles (alpha is a helium ion and beta is an electron). Either that or I’ve gotten all my chemistry knowledge assed up, which I have been known to do on occasion. 
Gamma rays are high-energy photons. Electromagnetic radiation consists of photons, but often acts like a contiuous wave. Wave-particle duality is so much fun :).
Rick
It is, though. The quantum of electromagnetic energy is the photon.
Quoth RM Mentock:
My bad. I meant to say that pitchblende produces penetrating rays capable of exposing photographic film. I don’t know if the relevant rays are gamma or X (produced by fluorescence from gammas, perhaps?).
And scr4, there are safeguards in the body, but they’re not perfect (just awfully darn good). That’s why I said it’s only theoretically possible, but not likely.
Nah, the current theory is that a cell must have a minimum of 5 exposures to a mutagen in order to develop into a cancer cell. One gamma ray isn’t going to kill you, it takes repeated exposures. Remember, mankind developed in an environment with significant background radiation. We’re adapted to it. Radioactive isotopes are a natural part of our body, since all chemicals are made up (to some small degree) of radioactive isotopes.
I should also note that Radon gas does not accumulate naturally, it is only found in poorly ventilated basements. People only develop cancers from Radon after years or decades of living in radon-filled basements.
I challenge the previous poster to document his claim that uranium ore in African mines has gone critical. It can’t be true. Uranium ore cannot go critical, it has to be refined.
**
Sorry mate, but you are wrong. Sustained nuclear chain reactions have been found to exist in nature. Specificly, nine natural reactors in Oklo Africa.
For more information you can go here…
http://ymp.gov/about/science/geninfo/oklo.htm
Or are you going to be picky and claim you said “critical”?
Jeff_42
Try doing a search for NORM [naturally ocurring radioactive materials].
Since you are excuding deaths caused by getting the substance inside you [eating or breathing], I would guess your answer would be no.
Getting back to the OP, wasn’t Madame Curie eventually taken out by cancer, reputedly caused by the radium she spent much of her life being intrigued by?
I’m going to be picky, but not over the word “critical.”
You were challenged, and rose to the challenge. However, the documentation does not meet the standard. The paper you cite describes some scientists who found evidence of unusual LOW concentrations of certain uranium isotopes in uranium ores. They theorize that these isotopes were depleted by a chain reaction something like 1.7 billion years ago.
There are no current self-sustaining chain reactions (critical events) known in nature. These Oklo mines don’t have any current chain reactions, the assertions that there were such reactions are educated guesses about what happened aeons ago.
She did, in fact, die of cancer, and radium, polonium, and the other radioactives she worked with are the likely culprit, but you can’t just pull a rock of radium or polonium out of the ground-- Both are present only in trace amounts in uranium ore. If I recall correctly, the Curies had to go through tons of ore in order to extract a few milligrams of radium.