The Trump administration has opened an investigation that could result in tariffs on rare-earth minerals and other critical materials. The news has the two large U.S.-based rare-earth companies moving higher.

Shares of USA Rare Earth (USAR 24.78%) were up 20% and shares of MP Materials (MP 12.80%) were up 12% as of 10:30 a.m. ET following the reports. Energy Fuels (UUUU 10.90%), a uranium producer, is up 10%.

A trade war beneficiary?

So-called rare-earth minerals aren't very rare, but there is a limited number of companies that are in the business of refining them. It tends to be dirty work and the U.S. has in recent years relied on foreign producers, but that could soon be changing.

The White House has ordered a review of mining and processing of rare-earth minerals to determine whether tariffs are needed to encourage domestic production. Although the review is preliminary, any tariff on foreign producers would help make U.S. producers more cost competitive.

Shares of USA Rare and MP Materials have been on the rise of late as these materials have been thrown into the middle of the trade war. Last week, China, which is responsible for about 70% of U.S. imports of rare-earth minerals, announced it was halting exports.

Uranium isn't considered a rare-earth material, and it is unclear whether it would be caught up in the new tariffs. However, investors appear to be bidding up Energy Fuels shares based on the reports.

Is now the time to buy rare-earth stocks?

For all the fuss made about rare-earth materials, their relative importance is somewhat underwhelming. The U.S. imports less than $200 million worth of these materials annually, and much of what is used goes into magnets that power vacuum cleaners and industrial applications.

That's not to say there won't be opportunities if the tariffs are put in place. But with USA Rare shares up 117%, Energy Fuels up 20%, and MP Materials up 18% in just the past five days, investors would be wise not to be in a rush to buy in right now.