A Swedish mining company said this week that it had found Europe’s largest known deposit of coveted rare earth metals, critical to many green technologies including electric vehicles, in a far northern part of the country within the Arctic Circle.The world’s production of rare earths is dominated by China. The discovery by LKAB, a state-owned company, creates the prospect that Europe could over time develop a domestic source of these minerals.“This is good news, not only for LKAB, the region and the Swedish people, but also for Europe and the climate,” Jan Mostrom, the company’s chief executive, said in a statement.Finding the deposit, estimated by LKAB at more than a million tons, is one thing, and extracting the metals is another. LKAB said it could take 10 to 15 years or more before the metals were delivered to market because of the lengthy environmental studies and other work required to open a mining facility in Europe.