Bob - You should have described the strike you have a bit better since the Mirage had several but a good bet as to the value would $10 to #14. What you refer to as gold trim is brass, the number minted is know only by the mint that struck the strike and for what ever reason the people who make the strikes like to keep the mintage figures a big secret but a good bet is there are more than 1000 of the type you have, the casinos have them as collector coins or call the limited edition ten dollar gaming tokens, and people like to collect them.
Fine silver is .999 fine where as sterling silver is .925 fine ( not as much silver in sterling )
Hope this helped you.
Walt