Vikings picked silver. China picked silver. Sparta picked iron. (Granted, that was kind of a special circumstance. But at times China used iron too. On the other hand, China never used monetary gold.)

As described, there can't be a good article on "why every civilization picks gold as its currency" because the premise is false.

The article acknowledges this as to silver, though not as to iron. On the other hand, the somewhat bizarre premise that currency has to be one or another chemical element goes unquestioned. Historically it was common to use grain as a currency. Even among metals, we know electrum coins have been used to great success.