"You know my feelings about arming morons: you arm one, you've got to arm them all, otherwise it wouldn't be good sport." - Judge Flatt, _Nobody's_Fool_

The ancients knew how to make glass!!! OMG!!! LOL!!! WTF?!?

"NEXUS is an international bi-monthly alternative news magazine, covering the fields of: Health Alternatives; Suppressed Science; Earth's Ancient Past; UFOs & the Unexplained; and Government Cover-Ups. "

Enough said. Too much, actually...

But let's all be paranoid, shall we?

If you have lead, you have a material that at one time was uranium. All radioactive elements decay into lead.

There are still uranium deposits that are mined today. In earth's ancient past, these were more numerous. There were seams of uranium large enough that if, say, seismic activity pushed them together, it would have reached critical mass and resulted in a nuclear blast.

There. No ancient atomic cultures needed.

Only highly refined iosotope U 235 (or the even more rare U 238) or Plutonium, which is not a naturally-occurring element, could create a fissionable reaction, and then only when bombarded by slow-neutron source, such as radium; spontaneous fission is nearly impossible to achieve in Uranium isotopes, even under ideal conditions, and the probability of uranium ore in its natural state undergoing such a reaction is statistically zero.

More likely, the "fused green glass" described in the article is a form of Uranium Glass, which is simply common glass infused with small amounts of Uranium Oxide. Although not known to be in common usage prior to the late Roman Era, this could certainly be an example of an isolated use of the material, not previously known.

Uh. No.

As quantities of fissile material approach one another they "burn off", reducing the total fissile mass to sub-critical mass. This was the challenge of the Manhattan Project: creating a critical mass quickly enough to generate a blast rather than a fizzle. Ultimately, the easiest method was to fire a uranium bullet into a sub-critical mass of uranium to create a sudden critical mass that would result in a expanding chain reaction and give a blast.

So, in order to avoid an ablative burn-off, the two sub-critical masses have to be brought together at speeds in the range of hundreds of meters per second. Otherwise you’re going to end up with a simple meltdown. It’ll be hot, but it won’t be an explosion and it won’t create a disbursed quantity of glass like the one that has been found in the deserts of the Middle East.

It pretty much has to be a meteor hit.

And the other likely explanation for the "green glass" would be either a meteoric impact, volcanic explosion, or possibly even a fire that generated sufficient heat to melt silica (containing trace amounts of Uranium ore) into glass.