RI State Quarter seems to be missing clad layers

[A&PCommonCents]

Good Day All,
Newly added member to CONECA.
Have been collecting coins & currency for some time and have recently expanded my interests to include error varieties.
This being my first post, I am looking forward to hearing thoughts on my assumptions of missing clad layers and if this is the case, perhaps some ideas on why coin weight seems to be higher on the “missing layer” 2001p RI state quarter, than one seemingly intact. I’ve included photos of coin comparisons and with this being my first post, would appreciate any feedback on content included on this submission, ensuring future posts follow the best practices. Appreciate the time and efforts of those reading and responding. Thank you so much!

[eaxtellcoin]

Hello A&PCommonCents,

Welcome to the forum!
This post belongs in the Mint Error forum, I will move it there to get you an answer.
To me the coin appears to be cleaned with a mild acid, then put back into circulation.
We'll see what others have to say.
Thanks for posting.
Eric

[A&PCommonCents]

Thanks for moving it Eric, will be interested in learning what type of acid would be strong enough to remove the layers without seemingly harming the coin design. Guessing you folks see all kinds of false positives

[Zimmy]

First of all, missing the clad layer on both the obverse and reverse is very scarce so anytime you are exposed to this situation, you should be very skeptical. Regarding the subject coin, each clad layer weighs 1 gram, so missing both layers would result in lowering the overall weight of the coin by 2 grams. Therefore, a coin missing both layers should weigh approx. 3.7 grams, which isn't even close to the subject coin's weight. Secondly, there will be significant weakness in the strike due to the planchet being much thinner than a normal planchet. The subject coin does not exhibit any significant weakness in the design details. The darkness of the subject coin appears to be from environmental damage. Even though the coin's weigh is less than specs, it is still within tolerance of a normal quarter. Based on the above analysis, the subject coin is not a mint error but has been subject to environmental damage. It's also possible it could be some type of annealing error but definitely not missing both clad layers,