Silver oxide is the black stuff that accumulates on bare silver.
It can't possibly be that chemical form of silver in your glass.

The salts used were silver chloride and silver nitrate. The silver and the other ion come apart in the heat of the metal, silver ions and chlorine gas are released. (I'm not sure what the nitrate turns itself into.) The metal ions react with the hot metal, giving rise to colours which depend on the exact temperature of the hot metal.
What silver and glass can do together is extremely complicated.
When you find an electric blue "haze" in a thick casing - that comes from silver metal ions, floating, dispersed in the glass.
Silver can go both blue and yellow with glass. It turns yellow glass, green; clear glass, yellow; and red glass, brown.
And even silver nitrate and silver chloride salts behave very differently. Silver chloride melts directly from the crystals into a liquid in heat.
Silver nitrate is a white crystal that sucks water out of the air and burns everything it comes into contact with.
Both are really difficult things to handle and are also very expensive.
I do suspect your new obelisk is a rather unusual one, yes. But I haven't paid too much attention to them, they're too much like paperweights which I
try to avoid.

I've got glass on the frames in my windows, as well as on the sills.
Don't forget the top of the loo and tops of kitchen cupboards, the corner in the turn of the stairs,
under the shelves... and don't bother with a flat screen tv. It's absolutely useless for putting stuff on.
