Found this one last night. I throw all 82s into a pile. The zincs, being less common, I save (not sure why ) The others go in the copper pile. Others have said that weighing each individually is too time consuming. I disagree, and so I weigh every one before I even look closer at them. This one weighed over. It was 3.16G, which is still within the allowable limits, I know, but I rarely see them err on the heavy side.
I saw the shiny line and the green oxidization, and was about to dismiss it as PMD and toss it in the copper pile when I noticed the raised metal behind Lincoln's head. Then I saw that the shinier strip of metal was actally formed into the letter "I" in LIBERTY
So then I'm thinking 'struck through wire'.... but after searching images of other cents struck through wire, I noticed that on every example the wire was noticeably thicker. It was also usually made of steel such as one would find on a wire brush. It is usually one straight, uninterrupted line.
A closer look at mine shows considerably thinner, copper, curved lines that even branch off in places. So I've now come to the final determination that copper filings fell off the die, accumulated during many strikes, and onto this cent, where they were struck into it. They are embedded and are even parts of letters in words, and span most of the entire obverse. Enjoy!