“Mention the word radioactive and most people will recoil in horror.” (Barrie Skelchers)
Must admit he’s right and the first time I’ve seen the uranium glass, I was concerned about safety and radiation hazards. Then I started searching for more information on it, and after getting convinced that it’s relatively safe, I even purchased a few Uranium 238 marbles.

According to various sources it appears these marbles contain approximately 3% Uranium 238.
The Uranium is added to the glass in molten state. After the mixture gets colder the color changes from red-hot to the well known pale green.
More info on the uranium glass here.

An interesting feature is the green fluorescence under Ultraviolet light. I’ve tried this myself, using a couple of UV LEDs emitting 390nm light.

This effect is caused by the Uranium contained in the glass.

Radioactivity
Ok, I should have started with this subject. Unfortunately I don’t have a Geiger Counter yet, but planning to purchase one soon, so I was unable to measure the radiation emitted by my marbles.
From what I currently know, these marbles do not emit high or dangerous levels of radiation, and are completely safe to handle.
I didn’t measure the radiation, but this guy did. See his page for some interesting readings on various sources of radiation.

It looks like radiation is all around us, even inside our bodies, mostly because of a potassium isotope emitting beta rays. A large quantity of radiation is present even in the air we breathe, because of natural occurring radon gas which is radioactive. See this chart for natural sources of radiation:

And read more about them here. Get informed!

Radu Motisan