You can find a lot of information on this site: https://en.numista.com/catalogue/pieces14444.html Numista.com is a great site for World coins. If you scroll down on the site provided you'll find your coin was minted at San Luis Potosi KM#407.7
The silver value is $6. The coin is damaged (hole) and some green goo on the reverse (verdigris?) or PVC? That might come off with acetone. In good condition this coin might bring $25-$30 but the condition is so bad, it could only bring a little more than melt.