Glass Balls

While railfanning between Barstow and Needles I found two glass balls many, many miles apart laying in the ballast rock near the rails. Each is about 3/4" in diameter and they are full of air bubbles. Anybody know what they are and where they came from?

Doesn’t look like anyone’s going to answer–too bad. I found a couple of those little balls out there about 5 years ago and have been curious about them ever since.

On another train forum I had an answer from a BNSF conductor that said they were all over the Barstow yard. Apparently they fell from gons on the way to a glass manufacturer. Best as I can tell they are going to be made into other glass things.