The Republic of Mexico issued these big, bold silver coins starting in 1870. It was a transition period for Mexico, and the old reales and escudos denominations were fading out. You might remember reales and escudos from the 'gold dubloons and pieces of 8' era of early American history, when Mexican coinage circulated freely in the United States.
The word LEY on your coin means 'law.' The silver is 0.9027 pure in this coin. In fact, these old pesos contain 0.786 troy ounces of silver, so that gives them intrinsic value right off the bat. Look up the current price of silver (in US dollars per troy ounce) at web sites such as kitco.com. The price of silver changes every day.
A good way to get approximate catalog value for these coins is to add a 'collector premium' to the base silver value. Suppose, for instance, the price of silver is $20 US dollars per ounce (be sure to look it up). The base silver value of this peso is then 0.786 x 20 = $16. To this value, add the collector premium:
worn: add $8
average circulated (like our picture): add $30
well preserved: add $120
fully uncirculated: add $300
These are approximate catalog values which must be properly interpreted, as outlined on our Terminology page.
There are some *better date* coins which exceed these catalog values by quite a bit. Specifically, look for:
1869OaE catalog value $400 in average circulated condition
1870GaC catalog value $800 in average circulated condition
1870PiS catalog value $400 in average circulated condition
1872CHP catalog value $800 in average circulated condition