Cobalt is the most important mineral of the future. It’s a key part of lithium-ion batteries, which power cell phones and laptops, not to mention electric cars. That demand is giving rise to a mining industry in Idaho, which sits atop a giant cobalt deposit. But the environmental costs of extraction raise questions about what “clean energy” really means. Guest: Michael Holtz, freelance journalist and author of “Idaho Is Sitting on One of the Most Important Elements on Earth.” If you enjoy this show, please consider signing up for Slate Plus. Slate Plus members get benefits like zero ads on any Slate podcast, bonus episodes of shows like Slow Burn and Dear Prudence—and you’ll be supporting the work we do here on What Next. Sign up now at slate.com/whatnextplus to help support our work. Learn more about your ad choices. Visit megaphone.fm/adchoices