How about silver, it a hell of a lot cheaper and more available than gold. The mountains in Mexico are lined with silver.
Actually, we used to have a bimetal or dual metal monetary system. And historically silver and gold floated at about a 1 to 16 ratio. As far as I know, silver bullion is still held at Ft. Knox. But, you raise a crucial point.
Silver has very little commercial value anymore. But, gold is a critical industrial resource. So holding gold bullion causes the price of thousands of goods and services to rise. We might consider adding silver bullion to our vaults. But, consider this, the national debt is what deflates the value of the currancy. If the debt were gone our greenbacks would be worth more than any other currancy in the world. No one would care about what was in the vault at Ft. Knox.