25 Dollars Tanzanit

Tanzanite is found in a single location on earth — a few square miles near Arusha, Tanzania, at the foot of Mount Kilimanjaro. Geologists estimate the deposit will be exhausted within decades, which has driven a cottage industry of tanzanite-set collectibles. Liberia, a nation with no geographic or historical connection to the stone, issues these pieces under its coinage authority primarily as a vehicle for the bullion-and-gemstone collector market rather than for any monetary purpose.