Um.. ALL modern dimes are made of copper. As are all post-1964 quarters and post-1969 halves. The current composition of post-1964 dimes and quarters is an Oreo of 91.67% copper between 8.33% nickel. If you've ever found a red dime or quarter in your hunts, it may be either because the copper is leaching through, or the nickel has eroded away. They are still spendable in any case.
If it's not showing great detail most likely the cladding is gone, I have a penny I thought was a 43 steel until I looked closer, it was a modern penny without cladding, looks completely gone.
I am not too smart but the plating on a dime? Coins are stamped with dies, which means the image we see has been pressed into a planchet, the flat piece of combined metals. I have found some red Washington quarters and could see all of the detail I needed to recognize it as a quarter but the copper was leaching through. You may want to google how coins are made, this will give you an idea of what you are looking at provided you are thinking of the elements, the circulation wear and tear, the metals used to make the coins and anything else that may have put the coin in its current condition.