The story goes that Champion Agate's glass furnaces were scraped, and the resulting residue was made into these marbles. Unfortunately, as noted, the glass tends to fracture, and examples with no fractures are rare."
David , Is this the statement that you are referring to? This is the myth. See Ron Shepherds and David McCullough's statements in Al's posts. That and what I posted about the myth is the truth. Please don't help to proliferate this myth. It was Wissmach glass, not furnace scrapings that went into those marbles.