For some examples of similar coins posted on this forum before, see the following threads:
http://goccf.com/t/424211http://goccf.com/t/435304http://goccf.com/t/416392http://goccf.com/t/333177http://goccf.com/t/413882Zinc cent blanks are copper-plated by the external contractor prior to delivery to the Mint. So the plating is already on the blank when the coin is struck. The only way - the
only way - that damage like this can occur is if something mechanically shears off the plating and removes the high points from the coin, some time after it is struck. SInce it can;t happen while the coin is being struck, it is not a mint error.
You don't even need a "grinder" or dremel to do this (though those will also work just fine for the purpose) - a regular piece of emery paper or similarly fine sandpaper will do. Try it yourself - get a perfectly normal, coppery-looking cent, and some fine sandpaper. Put the coin face-down on the sandpaper and rub the coin back and forth. After less than a minute, you will -
will - end up with a coin that looks pretty much like this.
As for the weight, perhaps the coin weighed slightly more than the standard 2.5 grams before it was sanded down. If you do the emery paper experiment yourself, weigh the coin before and after, to see how much mass is lost by the process.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis