Plutonium ? Radioactive ?

[newmarblemom]

OK guys ! When exactly were you planning on telling me about these ? 

My son recently became facinated with black lights so I got him a little black light flashlight. Imagine my sunrise when he walked into my dark bedroom last night and my marble corner lit up like an airport ! Any ideas on these fluorescent guys ?

[Parmcat]

Marbles that glow green have uranium glass in them.  It's not uncommon, and a lot of modern makers still use it.  I used to think it meant the marble must be old, but that's not the case.

If they glow orange that is cadmium glass

I still check all my marbles and enjoy the glowers

[newmarblemom]

On 10/24/2025 at 5:00 AM, Parmcat said:

Marbles that glow green have uranium glass in them.  It's not uncommon, and a lot of modern makers still use it.  I used to think it meant the marble must be old, but that's not the case.

If they glow orange that is cadmium glass

I still check all my marbles and enjoy the glowers

About 99% of my marbles are pre 1970 but my kids have gifted me a few modern ones. The ones with speckled of glow are the newer ones. But what a very cool discovery my son made that night because I had no idea this was even a thing ! I gave my cousin a couple of very cool oxbloods a while back and I now literally keep myself up at night wondering if they were plutonium ! Lol