Found a very strange 1900 Indian. Same exact diam and thickness as normal coin but very shiney and weighing at an incredible 4.6 grams. It does not stick to magnet. Actually had written it off as just a cleaned coin until I heard about the rare 2.50 planchet on Indian heads. Nothing makes sense on this. My understanding is even they were only 4.1 grams. What other metal could weigh so much? Help.