Yes, it's glass. The original claim by the manufacturers of the
material, sold to faceters by the ton, was that it contained ash
from the eruption. It was available in at least 3 shades of green, I
still have some here (I lived in WA at the time). Testing has shown
that it does NOT contain any ash from the mountain, none.
I know who was making it and I know their sole agent at the time.
His remark was "Well, we waved some ash over the melt, does that
count?". It was trickery, designed to sell a bunch of green glass to
faceters and to the public, and it worked. It's still happening,
visit Sea-Tac airport sometime. The vendors will GUARANTEE it is
made from ash from the eruption.
EVERYONE who has used ANY ash from this explosion as a glass melt
additive has achieved the same result.....an opaque brownish glass.
All attempts to make a glass or glaze from the ash. whether in a
reducing, neutral or oxidizing environment yields opaque brown/black
material. The whole thing is bogus.
The more recent material has a small amount of lead added to raise
the RI, and it is very pretty. But, so is faceted Coca-Cola bottle