Tina -- Your tanka does not look like a modern copy. Most of these that you see are just that ... modern copies. Instead, yours looks like an antique bronze Ram Darbar temple token with a thin silver plating.

I am not an expert on these, but I'd guess yours is worth $25 US dollars, or so.

For more complete information, see this page:

https://coinquest.com/cgi-bin/cq/coins.pl?coin=521