Well, this is about ball mills:
Ball mill - Wikipedia
I tried to find a standard link which is used to explain the Atlanta/Tennessee marble hoax, but it's not coming up for me in Google. Maybe someone else knows the link.
Here's an old old thread I posted on the subject ... linking to other threads which probably aren't there anymore.
https://marbleconnection.com/topic/6908-mostly-pix-fake-chinas-tennesseeatlanta-porcelains
It's definitely time for a new thread with more direct information, better pix and fewer external links.
After I made that thread the kinds of decorations that we encountered on the mill balls has expanded. But I still don't recognize yours. So if yours does turn out to be one, then the designs have expanded a little farther.