I'm not so sure that it's unplated (missing nickel as in cupro-nickel) as it looks like environmental damage.
These clads are rarely missing both sides, it would be significantly under weight. Environmental damage for sure
That is environmentally damaged. Missing the unplated it would all be one color, not spotted so to speak.
It would be rare to be unplated on both sides. It would also be thin and light. If you weigh it and it is not missing any weight, it can't be missing a clad layer. This is what a missing clad layer looks like:
That's not what someone did to this one. This one most likely came out of the ground. And what you see is rust, environmental damage/ toning. Yours has no copper color at all. Just compare the color in your coin to the one I posted and the video.
I think it's environmental damage too. When you CRH, you are bound to find copper plated coins, nickel plated coins, silver/gold plated coins. Novelties folks buy and grow bored of or perhaps the 7th grade science experiment. But those that metal detect will attest to finding coins of all shades and colors. Soil content, exposure to this-and-that will do funny things to coins. And unless you have an attraction to these coins, they generally get spent and back into the vast pool of coinage. At some point, a few wind up here for us to debate. Fun for us but generally disappointment for the poster. The 'cool' items generally end up being spenders.
I will turn this one over to a fellow collector friend. Who has a set of "Ugly Quarters" although he won't want it unless it's a downgrade from one that he has in that hole!
Quarters are not plated they are Clad. Here are many examples of the clad affected by Environmental Damage that I have found metal detecting -. Even nickels Clad layer and nickels are made of Cupro-Nickel. They contain copper which is affected by long exposure to the elements. Dirt, soil, sand and water.
You find them stuck to a console in the junk and soak them in a bottle of coke to clean them. That will do this to a coin.
I also clean gunky coins in muriatic acid (I happen to have it laying around and it's cool on the zincolns). And yes, I clean the cents with nickels, dimes and quarters and they all get various streaks of copper wash on them. The damaged zincolns on the other hand fizz away (cool to watch). Collectors can rejoice and be thankful for the confusing PMD ...
Of course Paddy is correct and I misspoke in my first post (which I corrected later). It's not plated or unplated. It's a clad coin. And it's not missing a clad layer.