OK, the picture is small so I can't be 100% certain. I'm pretty sure that coin is not silver it's a copper-nickel-zinc composite. I'm also pretty sure it's actually from Republic of China aka Taiwan (I think Formosa is the Portuguese name for the island). It looks like a 1 Yuan coin, but I can't tell the date with such small pictures.
Here's a picture from the world coin gallery:
http://(131231) Not Allowed - Auto-Removed /countries/coin.php?image=img1/42-536&desc=Taiwan%20y536%201%20Yuan%20(1960-1980)
Here's a picture from the world coin gallery:
http://(131231) Not Allowed - Auto-Removed /countries/coin.php?image=img1/42-536&desc=Taiwan%20y536%201%20Yuan%20(1960-1980)



















