I doubt you have an error coin. It's much likelier that it oxidized this color, which is possible because they are made mostly of copper; or that the outer layer was removed with acid.
📋 Item Submitted
1995 D quarter error bronze on front and back
M
Marc's Expert Appraisal
ANA-Certified Numismatist · Hudson Valley Numismatics
Similar Appraisals
1982 no mint mark error Penny. 1920s standing liberty quarter
I can’t discern any error or much of anything from this photo, it’s blurry and cut off. Sorry.
This quarter weighs exactly the same as a regular quarter
I'm so happy for it!
2014 P quarter. can't really tell much more about it . Thanks. Jeff
Not much to tell... damaged I'm afraid.