Alan

Yeah - thats why I asked for another view of it. It looked wrong.

I would be interested in seeing pics of it in better light.

Have you considered that they may be scratches in the iridescent layer?

I looked at the pics carefully and all of the black appears on the surface in my viewing. Also - if it is iridescent, which it appears to be - how could anyone see into the center of the marble?

Looks like crud on the rollers.

That is all wrong for vintage.

Pics are fuzzy - but Ravenswood.

I believe that half of it is broken off, which is why it was discarded.

Either excess colorant precipitating - as you say, or added and not chemically dissolving, or a chemical reaction between other colorants or other cullet chemistry.

There can be excess colorant in most dark glass colors. Its most common in green glass - but its possible in most, including red.

Vintage marbles were made for ~ 1/15th of a cent each in a crude manufacturing process. Don't look for precision. You'll just be disappointed.

It appears more like a shear defect on a game marble.

Where is the "pontil"?

Someone's early torch experiment. I don't see a pontil and there shouldn't be one.

Good decision.

x2

7/8" Tiger (left); 1" Bengal Tiger (right):

I'll point out that the hot glass is still viscous when it hits the rollers, As it spins down the rollers, glass can form a "9" or other wrapping patterns before it cools.

Who established that - and specifically how?

Agree. I think the first piece has an even chance of being Akro, but there is no clear pointer either way.

What is called "aventurine" (aventurine is actually a mineral) is formed one of two ways. The far most common way is by accident by adding too much colorant to the batch (its added by the shovelful) in the form of various metal oxides which crystalize as the glass cools. The far less common way in intentionally - as Peltier did with a number of their better marbles. This latter approach was a bit more costly and created a very dense crystalline patch. Over-saturating the batch a bit with colorant wasn't uncommon, especially it seems with green glass. As I've said before - there wasn't a big wooden barrel at the marble factory with the words "AVENTURINE - USE SPARINGLY !" printed on it with some magic powder inside. Marble making wasn't rocket science and vintage marbles needed to be made for tiny fractions of one cent.

Foreign Cat with undissolved colorant.

Not for me.

1. Divided core 2. Latticinio core FYI - your camera is focusing on the background cloth, not the marble. Its better to manually choose center focus. Then your subject won't be so blurry.

Akro