I say most part because there are exceptions like gold / silver, land banking and development. 

A good contractor is worth their weight in gold, and they're very hard to find.

If you can snag a property with separate metering, then you're essentially buying a duplex with free standing units (with residential low down financing), and that's worth its weight in gold. 

This is gold even now. 

A solid financial reputation can be like gold.

He has a heart of gold but his life is almost always having some crisis going on with getting into debt with bad choices or wanting to change jobs etc.

You think about the Richest Man in Babylon, one of the primary ideas is "protect thy gold."

. #2, ******BP, I cannot stress this answer enough****Read this twice as it is IMO gold!! 

This is talked about in the book: "The Richest Man in Babylon" The clay tablets with the information of how to make, save, invest and keep wealth are worth a lot more than the purse full of gold.

I once owned an international gold fund based on a speculation of a falling U.S. dollar.