On the tangent of chalkies, the story above isn't how they came to be. It was supposed that it was possible until we found out that the chalk IS the ribbon inside and out. A chalky broken in half has chalk on the inside. In fact, a chalky was put into an acid and it ate out the chalk and left a marble full of wormholes where the chalk was. I wish I could find a pic. The chalk was in the tank and coming out with the stream of glass. I don't know if it was a component of glass that didn't get mixed, someone goofing around with lime or something similar, an accident, glops of mortar that fell in during tank repairs, who knows. But it does go throughout the marble, not just on the surface as it would be from rolling on lime or a reaction from the ground they were buried in.