To power AI, Khosla and a16z bet this startup can reinvent mining

Turner Caldwell doesn't think oil built the last century so much as metals did, and he's betting metals will build the next one too. His startup, Mariana Minerals, just closed a $310 million Series B led by Khosla Ventures, with Andreessen Horowitz, Breakthrough Energy Ventures, BHP Ventures, Mitsubishi Corporation and a long list of others piling in. That brings the three-year-old company's total raise to $400 million and pushes its valuation to $1.5 billion, according to Fortune, which got the numbers first.

The pitch is straightforward even if the industry it's targeting is anything but. Mining is centuries old, capital-intensive, and slow, and China currently controls up to 90% of global critical minerals processing, with that figure climbing to 92% for rare earth magnets used in phones and defense gear. Caldwell, who spent nine years building factories at Tesla before cofounding Mariana in 2024 with Baker Tilney and Juan Lozano, wants to run mines the way a software company runs infrastructure: automated, fast, and cheap enough to bring costs down across copper, lithium, aluminum, nickel, cobalt, manganese, uranium and rare earths.

Mariana isn't just talking about it. The company restarted an idled Utah copper site, called Copper One, in four months using autonomous operations, and says it's ramping toward 50,000 metric tons of refined copper a year there. A second project, Lithium One in Texas, broke ground in 2025 and should hit commercial production by 2027. Both sites soak up chunks of that $400 million, meaning Mariana is spending real money on real holes in the ground, not just building dashboards.

The timing lines up with the AI industry's sudden, voracious appetite for physical stuff. Travis Kalanick, who now runs robotics company Atoms, put it bluntly: you cannot lead the AI era without a domestic supply chain, because every data center, chip, grid upgrade and EV traces back to copper and a handful of other metals nobody thinks about until they're scarce. Caldwell frames the whole modern economy as an electrification story, and electrification runs on copper. When copper prices spike, as they already have, everything downstream slows down.

Mariana will still have to go toe to toe with giants like BHP and established lithium players like Standard Lithium, companies with decades of infrastructure and relationships Mariana doesn't have. But the bet from Khosla and a16z is that being smaller and software-native might be the point, not the handicap, especially with the AI boom turning mundane metals into geopolitical flashpoints almost overnight.