These odd medals were struck sometime in the 60s by the Mexican private mint 'Central de Numismatica y Medallistics' located in Mexico City. They also struck many other commemorative medals, including one of JFK's brother Robert Kennedy, as well as some medals of Dutch queens and Aztec fantasy tokens.
We know of both a silver and a gold version. The silver version also comes with English text on the reverse - this variety also carries the words 'CENTRAL NUMISMATICA - MEXICO' at the bottom.
These medals are worth their weight in precious metal, plus a small premium. Look up the current gold or silver value on a website such as Kitco.com, then multiply it by the amount of troy ounces in the medal, as listed below:
SILVER: ~1.4 troy ounces
circulated: base silver value
fully uncirculated: add $15 USD numismatic premium
GOLD: ~1.3 troy ounces
circulated: base gold value
fully uncirculated: add $80 USD numismatic premium
There is, apparently, quite a bit of variability in these medals. Please note that the above values are only correct if the metals are struck in very pure (0.999) silver or (24K) gold. We are not sure what the actual purity of these medals are, but an obliging reader named Kyle found an example that was 90% gold and 10% copper, with an actual gold weight of 1.8 troy ounces. To make sure your medal is made of precious metal, seek out a jeweler or coin store where someone can take an in-hand look at it.