This is a 1900-S double eagle in silver. It is ex Kreisberg 1/75, Bowers and Ruddy 6/75.
The following is excerpted from the Scott sale catalog from the Kreisberg description.
"Extra thick - 3.5mm thick at edge (normal coins are just 2 mm) Struck from what appears to be regular mint dies, but border denticles on obverse repunched to form beads, while those on the reverse are for the most part better defined than usual. The sporatic die rust on the obverse and bold reverse die cracks lead us to believe that this was struck subsequent to its date."
Pollock comments that Tom Delorey had seen a similar example in the ANACS reference collection of counterfeits.
Photo is a scan from the Bowers and Ruddy 6/75 Scott sale.