It could be oil, but it is rapidly depleting (8 more years and it is gone). Other would be silver, for which Mexico is the largest producer in the world.
Oil is the most profitable commodity extracted from the Mexican soil (it is worth US$41.6 billion in exports for 2013). It is followed by gold (US$5.69 billion) and copper (US$2.66 billion).
The most important natural resource of Venezuela is oil.
people
gold
coal
Grapes
Salt
oil
the most important natural resource in Puerto Rico is Elkhorn coral
is soil
ummm..
agriculture
The Sea.