Toulouse (M) mint Louis XVI Royal France silver ecu coin, larger and heavier than a US silver dollar.
Certified by PCGS to XF 40, toned.
There appears to be an overdate: 1786/5, but PCGS did not identify. The 1786/5 is published by Droulers.
Pedigree: very old Spink paper envelope (approx 75mm x 75mm).