A Southern Clay Manufacturing Company did exist, but I'll guess someone just came up with another story to explain the same old Tennessee/Atlanta Porcelain ruse.
Of course photographs could possibly change minds.
I'm not able to make out enough details of the marble to know. From this one angle, it kinda looks like it could be in the more corky moss agate family. But with other pics who knows what it might look like.
Who is the question to? Jess about whether there is opalescence? ... or me about finally capitulating and agreeing to the name "Ace" in spite of lack of opalescence?
In my mind I'm still calling it a moss agate. But it looks like what others call an Ace so if you can't beat 'em ...