The Nikkei reports that prices of rare-earth metals have reached record highs in the weeks since China clamped down on exports of the key materials used in electric vehicles, wind turbines and other items.

The price of dysprosium in Europe—the benchmark for the material outside China—tripled from the start of April to $850 per kilogram as of Thursday, according to Argus Media. Terbium increased to $3,000 per kilogram from $965. v

In early April, The Chinese government restricted exports of seven rare-earth metals, including terbium and dysprosium. The seven elements affected by China’s curbs are classified as medium and heavy rare earths. They are less commonly available than light rare earths, and China is responsible for the majority of their global supply.