NUUK, Greenland — More than a decade ago, Canadian miners prospecting for diamonds in western Greenland saw on the horizon a huge white hump.

They called it White Mountain and soon discovered it was a deposit of anorthosite, a salt-and-pepper colored mineral used in paints, glass fibers, flame retardants and other industries. The same mineral creates a ghostly glow on the moon’s surface.

The White Mountain deposit proved to be several miles long and several miles wide, and “only God knows how deep it goes,” said Bent Olsvig Jensen, managing director of Lumina Sustainable Materials, the company mining the area.

Lumina is backed by European and Canadian investors, but Jensen said it wasn’t easy to turn the deposit into a mountain of cash. “You cannot do exploration all year-round; you are in the Arctic,” he explained.

He told of fierce winds grounding helicopters and knocking out communications, pack ice blocking ships and temperatures dropping to such a dreadful low — sometimes minus 40 degrees — that the hydraulic fluid powering the company’s digging machines “becomes like butter.”

Sitting in Lumina’s humble offices in Nuuk, Greenland’s capital, with wet snowflakes falling outside the windows, Jensen clarified all of the talk of Greenland as the land of incalculable mineral riches. He noted that though the island has dozens of exploratory projects, there are only two active mines: his and a small gold operation.

The gigantic semiautonomous island in the Arctic has seized the world’s attention after President Donald Trump insisted in January that the United States take it over. Part of the attraction is its rare earths minerals that are vital to high-tech industries and a source of global competition.

China dominates in the world’s critical minerals and has restricted the export of certain minerals to the United States. The Trump administration, determined to secure mineral assets overseas, has turned to high-pressure tactics. The natural resources deal that Ukraine was set to sign with the administration until the talks blew up was focused on minerals.

According to a Danish study, 31 of 34 materials defined as critical by the European Union, like lithium and titanium, are found on the island. But for every square on the periodic table that Greenland can fill, there’s a longer list of challenges. Besides the extreme weather, the island has fewer than 100 miles of roads, only 56,000 residents and a few ports.

Equally daunting for miners is Greenland’s environmentalist lobby. Many Greenlanders say they need more mining to become economically and politically independent of Denmark, which keeps it afloat with hundreds of millions of dollars in subsidies.

But Greenlanders also have expressed caution about any new industry. They are protective of their environment, which is being shaken up by climate change.

The island’s governing political party swept into office four years ago on an environmentalist platform and shut down one of the most promising mining projects. The next elections are Tuesday, and, along with independence from Denmark and closer relations with the United States, safeguarding the environment is at the top of the agenda.