Appears like a coin from close moist contact with iron containing soil. Most often seen in metal detected or gardened coins.
I metal detect, and that color is very common for copper pennies that have been underground for around 5-10 years, after around 20 years they get crusty. A zinc cent that was underground for 20 years would be in worse condition than a copper cent underground for 500 years. On the other hand, clad coins have the same color as a brown copper penny if the are underground for 1-15 years, after that they get all crusty, meanwhile a silver or gold coin can be underground for 1000 years, and look the same as they were the day they were dropped. The oldest coin I have found metal detecting this year is a 1655-1658 "i" mint french Louis XIV Liard, I have also found a 1723 Wood's Hibernia this year, along with a King George II young head the next week. Along with a key date 1861 New Brunswick half cent, and a few large cents. Here is a really nice one that I found last month.
My father owned a small store and a customer stopped by one day wanting a pack of cigs. He paired with a box full of old coins. I remember one coin being a large one cent piece. I'm wanting to say it was from the mid 1800s. My father asked the customer if he was sure about paying with this old change and he said he was cool with it. That customer really wanted his smokes. I believe the others were barber dimes and mercury dimes.
I tried metAl detecting before but gave up for a little. Never found anything interesting. Back in Oklahoma there's an old cotton gin mill tucked in the woods. I would love to detect around that area.
