Proof Planchet?

I recently received a small lot of coins and in it was a blank 25¢ planchet. It looked a bit shiny for a planchet so I looked closer. It's weight is 6.8 grams. My scale is working right as I tested a couple quarters from my pocket. Under magnification you can see dimpling on the surface. It is the correct diameter for a 25¢. There are no signs of a copper core.
I'm thinking it is an overweight silver proof planchet. Could I be mistaken?

 

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could just be that someone polished it

 

Is that a rim on it? From the pic it looks like it has a rim, but the inside is missing.

 

It's definitely been through the upset mill with a well formed ridge. Maybe it's a foreign planchet.

 

Canada?