With a Gold IRA, one can buy gold, silver, platinum, or palladium that meet IRS purity requisites

https://us-mia-1.linodeobjects.com/temperance/GoldIRA/uncategorized/buying-gold-with-a-401k-a-short-report.html

With a Gold IRA, you will buy gold, silver, platinum, or palladium that meet IRS purity specifications. Your custodian publications each purchase.