KoBold Metals, a Berkeley-based mining company that uses artificial intelligence to mine for rare earth elements, has closed out a funding round that crowns it an A.I. “unicorn” worth $1 billion and ropes in some of the biggest investors in the world. The $200 million round, reported in the Wall Street Journal, included money from Breakthrough Energy Ventures, a Bill Gates–backed venture capital firm that invests in clean energy companies on behalf of people including Jeff Bezos and Jack Ma.