Marboman, not a fizz. The base should be clear on a fizz.
Rockgardenplants, that's a fizz in my book. It just proves that not all glow. It has every other hallmark, even the size. The black light wasn't even invented yet when that marble was made, maybe the bulk of the fizz marbles came out with UV reactive glass but some of the glass near the beginning or end of the run wasn't reactive? The factory workers wouldn't have known, they had no black lights. The size is right, it has the bubbles, it has the antifreeze green, and it has the correct construction. It's a fizz and if it doesn't glow then I'd say not all green fizzes glow. If you have two marbles that are identical and made by the same company around the same time but one glows and the other doesn't, does that mean they can't have the same name? I know of several named types where some glow and some don't. Still they retain the name. Just my opinion on it but if it was in my collection it would be a fizz.