Actually, it's a 1/2 real.
Note there is no "1" before the "R" (after "IND"). Had the coin been a 1 real, there would be a '1' in that position. Another way to determine the denomination is by its diameter. Your coin's diameter should be close to 18mm whereas a 1R coin would have a 20 mm diameter. Either way, both coins are composed of .9027 fine silver and were minted in Mexico City.
Congrats on your find !!
Don......
Nice find. The color looks a little off for silver. They did make counterfeits at the time. It's possible your's could be one. For size comparison, here's 3 pieces I found last year. A 2, 1 and 1/2 real.