Even so, I'm not sure how it would be possible to keep it a secret from the press, the public, and the government. A major mining operation and large-scale export of valuable minerals wouldn't be a secret for long. It wouldn't take long to be exposed.

I believe that in Venezuela, as in most countries, mineral rights belong to the state and not to property owners. If he wanted to enrich himself illegally, it would be much easier to set up a state-owned mining company and then skim from it. Or maybe have the company give sweetheart contracts to suppliers owned by his cronies or relatives. This is what usually happens in real life in these countries.