If you weigh it and tell us what it weighs, we can give you a better answer - but I'm almost positive that is an environmentally damaged/corroded plain regular dime. Worth about 10 cents, depending on the mood of the cashier.
I have a couple of dimes which are partially missing the nickel clad layer(see my avatar), simple lamination problem some are probably worth about 5$ in AU or better.
It looks like an example of environmental damage. Clad coins found at the beach or in wooded areas near me look exactly like that dime.
I'd still keep it for a conversation piece. I have a nasty habit of keeping mutilated and damaged coins.