Found this broken piece in the creek bank. Southwest Pennsylvania. Farmhouse was built in 1922. Coalmining country.
Would have been about 18" in diameter. There is a rough coating in the glaze on the inside and outside of the bowl section. Abrasive enough that I figure it served a mechanical purpose. There are three grooves on the rim that aren't symmetrical to each other.
There might be a makers mark in the center of the glaze inside but I can't make it out. There is also a light blue/green stain on the bottom that might be a mark.
Any ideas?
I do know that mines and other things would often bring their own electrical generators and systems and lots of PA has a history of coal and other mining. Someone knowledgeable in that sort of history might be able to confirm/deny that theory.