Cast copy? Harshly cleaned? Just typical slightly corroded aluminum? Japanese puppet "Provisional Government of China" 1942 1 chiao - aluminum, slightly smaller than a U.S. quarter. (Misdated as 1941 by the Brazilian seller )
Well, surface appearance isn't really related to the geographicl source. Casting was my first reaction too, but there isn't a very broad market for the Japanese puppet government issues, the coin only has a catalog value of $6 Unc., and the 1943 is worth more than three times as much, so I'm really scratching my head why anyone would counterfeit this one. The bid is at 99¢ with less than a day to go, but that $15 S/H puts the total over my personal limit for purchasing fakes.