There’s one metal that’s leaving all commodities—and even Bitcoin—in the dust this year. The challenge for investors is buying it.

Iridium, one of the rarest precious metals and mined as a byproduct of platinum and palladium, has surged 131% since the start of January, far beating Bitcoin’s 85% gain. It has rallied on supply disruptions in the past year and rising demand for use in electronic screens, refiner Heraeus Group said.

With a market much smaller than its more famous sister metals, production issues can have a big impact on prices. Betting on it is difficult too, as demand is dominated by industrial users. Iridium isn’t traded on a bourse or through exchange-traded funds, retail buyers are limited to ingots from a handful of dealers and the few major investors dealing in it go straight to producers.

“The lead time on the supply side is too long to increase supply in a timely fashion,” said Jay Tatum, a portfolio manager at Valent Asset Management. “The only near-term solution is higher prices to get people to sell their existing holdings.”

Iridium, which is also used in spark plugs, has climbed to $6,000 an ounce, according to Johnson Matthey Plc data. That makes it more than three times more expensive than gold.

Part of iridium’s appeal comes from the limited investment in production of platinum, which is largely used in autocatalysts to curb emissions, while investors weigh potential increases in platinum demand from new hydrogen technologies against a shift to electric vehicles.

The outlook for tight supply also helped drive up prices of other platinum-group metals. Palladium is about 9% below an all-time high, rhodium reached a record $29,800 an ounce this week and ruthenium has rallied to an almost 13-year high.