Pocket Change Error, Canada 10c

I was going through my pocket change and thought I had an United States dime as the copper is quite evident when stacked together. On closer inspection, it is a Canadian 10c missing the nickel plating on the obverse only.

Starting in 2001 the RCM changed from 100% nickel to .920 plated steel, .055 copper, .025 nickel.

I'm confused. If it's a nickel plated steel coin without the nickel plate where does the copper come from? Maybe the reddish color is from rusted steel?

Multi-ply plated steel (.920), thin layer of copper (.055), lastly a thin layer of nickel (.025). I believe the copper layer is added because it is softer than the nickel and steel and thus the dies last longer.

Maybe. I was assuming the plated layer was copper-nickel (.6875 Cu/.3125 Ni) but it makes sense that first a "strike" plate of cooper then the nickel plate was done. That's common in the plating industry since nickel directly on steel tends to flake off easily. One more reason I hate generic compositions that don't really tell the story. "Nickel plated steel" doesn't really allow for any copper.

Quote: "Peter M. Graham"​I was going through my pocket change and thought I had an United States dime as the copper is quite evident when stacked together. On closer inspection, it is a Canadian 10c missing the nickel plating on the obverse only.
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​Starting in 2001 the RCM changed from 100% nickel to .920 plated steel, .055 copper, .025 nickel.
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​Might be a Counterfeit

It could still be the nickle plate.
Nickle forms wide range of odd colored tones in contact with various environmental conditions.
If it lay on a pavement with a film of brake fluid for a few years one side could get corroded differently.