This came in the shop last weekend. It was in a 2x2 when we bought it. Weight is 4.7g First one of these I’ve owned.
https://www.sigmametalytics.com It measures resistivity and compares it to values of known alloys. If you have voids, laminations, or poorly mixed alloys, you'll get a false reading.
It does look like a contemporary counterfeit but I don't think its tin and charcoal. Probably just some low melting point pot metal. There may be some tin in it and other metals as well
Adding this to my Christmas list!! Haha, too bad it'll be a permanent resident on there. Thanks for the link!