Hoarding gold is for libertarians. Bitcoin mining is for nerds. Really adventurous investors—especially fans of the stranger stretches of the periodic table—ought to consider stockpiling something more intense, like industrially valuable exotic elements. Demand for these is on the rise, and you no longer have to be a global megacorporation to get your hands on some. Kitco, one of the leading precious-metal traders, is now minting rhodium bullion for customers, and a Massachusetts company called Metallium will sell you almost any (non-radioactive) element; most are now conveniently available as ingots or coins. So where to start? Here are five sweet spots on the periodic chart.