It is an 8 reales of Charles IIII struck at the Mexico City mint in .8960 silver. The correct weight should be 26.0674 grams with an ASW of .7797 oz. And yes, it appears to be genuine based on the pics, but weighing the coin would be advisable. Value in that condition would be about $50.
Thanks much for this information Thanks for the information. This coin was given to me for reselling but has peaked my interest again in coin collecting. Jim