Unfortunately I have no idea how big it is or its weight. It is being sold simply as "small foreign coin". Any ideas?
I'm not sure if it's ancient. The seller is also selling a bunch of Dutch East Indies coins. Looks like a Brahma bull on the reverse. I would guess something from south east Asia, and they were hammering coins up into the 19th century.
It is a bull and horseman Jital from the Shahi of Kabul (Afghanistan) from around 850-900AD. Above the bull it reads "Spalapati Deva". For classification, it is type Tye#5.