Investor interest in rare earth minerals is rising, a source of strength for shares in the rare earth miner MP Materials. The stock rose early on Friday after jumping late Thursday following a Bloomberg report that the Defense Department might provide additional capital to boost production.

Rare earths are among the most critical raw materials on the planet, deeply embedded in the technologies that underpin modern life. Yet few people have heard of them or know what they do.

The tentative deal between the United States and China may represent a retreat from the worst-case scenario of a total collapse of trade between the world's two biggest economies, but it creates more problems than it solves.