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Stick it to the salt for few days. It could suck out a lot of that oil or when your better half is not at home stick it to the dishwasher.

Then it is not Washita. Do you have any indication of origin from seller? Originaly I guessed your other stones were Thuris but they are normally softer.
Another option could be that what you have...

Still hard to recognise. Haw hard it was to lap it?

Can you show close up of the patern on the stone? From the pics it looks like oily Washita.