I've come across an 1992 5c coin, about unirculated, in a consistent deep brown/black tone.
Could this be original or perhaps environmental impact?
Attached photos of a regular 5c of the same year for comparison.
Have noted a slight-double rim on the left side of the portrait. I will place a mark for reference.
Haven't seen a coin like this before.
Would be greatly appreciated if anyone could give some insight!
Thank-you.

