Rare earths are among the most critical raw materials on the planet, deeply embedded in the technologies that underpin modern life. Yet few people had even heard of them until the eruption of the US-China trade war thrust them into the limelight.

China signaled it would approve the export of rare earth minerals in a statement Friday hours after White House officials said that the US and China had signed a trade agreement to work out tensions linked to US access to the key material.

The announcement offered hope of a reprieve on shortages that have hit American industry, and came after President Trump said he signed a deal with China.