Error Coin

coin error 1964 d 1 cent only weighs 2.6 g. had a pocket full of change and it sounded like I had a silver coin or something foreign . when I looked I didn't see anything out of the ordinary so I decided to throw them on the scale and this is what it was. not sure of what type of planchette it was stamped on it's not much thinner than your regular coin definitely not .5g of different size that's why it has to be a different metal Plus it just sounds different... (make me an offer)