These marbles are made of vaseline glass (https://en.wikipedia.org/wiki/Uranium_glass) and SWMBO bought them for some of her training sessions.
The green glow is produced by flourescence in the glass under UV light.
Rather eerie!
Vaseline Glass by John Liddle, on Flickr
The green glow is produced by flourescence in the glass under UV light.
Rather eerie!
Vaseline Glass by John Liddle, on Flickr
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