(CNN) A small island in the Pacific Ocean is the site of a huge discovery that could change Japan's economic future. How huge? One economist called it a "game changer." The researchers who helped find it said it had "tremendous potential."

It's mud. A whole bunch of mud -- an estimated 16 million tons, to be exact. And in that mud, there are massive, "semi-infinite" stores of valuable rare earth minerals.

Rare earth minerals contain rare earth elements (located here on the periodic table ) that are used in high-tech devices like smartphones, missile systems, radar devices and hybrid vehicles. For instance, yttrium, one of the metals included in this recent discovery, can be used to make camera lenses, superconductors and cell phone screens.

According to a new paper published by a team of Japanese researchers , this huge patch of mineral-rich deep sea mud lies near Minamitori Island, a small island 1,200 kilometers (790 miles) off the coast of Japan.

The 16 million tons of materials could contain 780 years worth of yttrium, 620 years worth of europium, 420 years worth of terbium, and 730 years worth of dysprosium. In other words, according to the paper, it "has the potential to supply these materials on a semi-infinite basis to the world."

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