IDK bro. In the event of a complete economic collapse people are gonna gravitate towards the most common (and timeless) form of currency, which is gold. Sure a trade and barter system will still exist, and will be the most common for of exchange for many years. But eventually people will choose a system of precious metals for exchange. Also, I have no idea why you think gold is a "common element of dirt". Go digging for gold in your backyard and report me the results.