A Gallium Nitride semiconductor wafer. Credit: European Space Agency In the ongoing contest for control over global supply chains, China has always had one strong card in its deck: Its dominance over the supply of rare earths and other raw materials vital to several advanced technologies. This week, it decided to play that card. The Ministry of Commerce on Monday said it would impose export controls on two little-known metals, gallium and germanium, effective August 1. The move sent shares of Chinese rare-earth miners rising, with investors expecting prices to increase. But it will also have alarmed governments already contending with high inflation and concerns over the openness of global trade. China produced 98 percent of the world’s gallium supply last year, according to the U.S. Geological Survey, with the metal prized for its ability to convert electricity into light and used to produce LEDs and lasers. Its compounds, such as gallium nitride and gallium arsenide, are strong conductors which can substitute for silicon in seSubscribe or login to read the rest. Subscribers get full access to: Exclusive longform investigative journalism, Q&As, news and analysis, and data on Chinese business elites and corporations. We publish China scoops you won't find anywhere else. A weekly curated reading list on China from David Barboza, Pulitzer Prize-winning former Shanghai correspondent for The New York Times. A daily roundup of China finance, business and economics headlines. We offer discounts for groups, institutions and students. Go to our Subscriptions page for details.