Mariana Minerals raises $310 million for software-run US mines
Khosla Ventures led the Series B, joined by a16z, Breakthrough Energy Ventures, BHP, Greenoaks and four other investors.
By Ryan Merket · Published
Why it matters
The round backs a capital-heavy test of whether software and autonomy can shorten US mine and refinery buildouts, with BHP joining venture investors.
Turner Caldwell (@tbc415) has raised $310 million for Mariana Minerals, financing a capital-heavy attempt to run US copper and lithium projects with software and autonomous equipment.
https://x.com/marianaminerals/status/2084277737896976773?s=46
Mariana disclosed the Series B Monday in an announcement on X. Khosla Ventures led the round, with continued backing from Andreessen Horowitz and Breakthrough Energy Ventures. Greenoaks, Halo Fund, Pax Ventures, StepStone Group and mining group BHP joined as new investors.
The financing gives Caldwell and co-founders Juan Lozano and Schuyler "Baker" Tilney a large pool of private capital for a model that combines startup software economics with the construction costs and operating risks of mining. Mariana owns and operates mineral assets, while keeping its software inside those operations instead of selling tools to established miners.
Caldwell previously led Tesla's metals and minerals team, working across lithium, battery materials and manufacturing projects. Lozano scaled machine-learning systems at Affirm and Kite. Tilney previously built an integrated energy operator that was sold to Vitol, according to a16z, which led Mariana's Series A.
That mix of mining execution, machine learning and project finance is central to Mariana's pitch. The founding team is betting that tighter control of software, engineering and physical operations can reduce the delays that routinely turn mineral projects into decade-long undertakings.
Venture capital moves downstream
Mariana's July 2025 Series A announcement put its total capital at $85 million. In an April 2026 announcement, Mariana said that figure had reached $120 million. The new Series B therefore implies roughly $430 million in announced capital based on Mariana's most recent prior tally.
The investor list also marks a change in the type of capital behind Mariana. Khosla Ventures and Breakthrough Energy backed Mariana before its Series A, while a16z led the 2025 financing. The new round adds growth investor Greenoaks, private-markets manager StepStone and BHP, one of the world's largest mining groups.
BHP's participation carries strategic weight because Mariana is trying to automate many of the same extraction, processing and maintenance workflows that established miners operate at much larger scale. The investment gives BHP exposure to Mariana's approach while giving Mariana an industry backer with direct knowledge of mine economics and expansion projects.
The round is also unusually large for Mariana's age. Founded in 2024, Mariana has moved quickly from a venture-backed thesis into ownership and construction of physical mineral projects. The capital will have to support equipment, processing plants and operating teams alongside the software development typically financed by startup rounds.
Copper One and Lithium One become the test
Mariana's first public operating test is Copper One, a copper mine and refinery in southeastern Utah where Mariana restarted mining operations on April 27th, 2026. The site had produced copper for more than 15 years before Mariana acquired it.
Mariana is deploying MarianaOS across geologic modeling, mine planning, fleet orchestration, plant control, maintenance and supply-chain management. Mariana says machine learning and reinforcement learning will be used to optimize drill patterns, truck routes, plant throughput and energy use. The system is intended to coordinate the full operation rather than automate isolated pieces of equipment.
Mariana has set a target of expanding Copper One to 50,000 metric tonnes of refined copper output annually. That figure includes copper from mined ore and recycled scrap processed through the site's refining circuit. The expansion remains a company target, and reaching it will require Mariana to prove that its software can deliver gains at industrial scale rather than in a controlled pilot.
The second project, Lithium One, is under construction in East Texas. Mariana plans to extract lithium from water produced by oil and gas operations through a partnership with Select Water Solutions. Mariana says the facility will be capable of producing up to 3,000 metric tons of battery-grade lithium salts per year, with commercial production targeted for the first half of 2027.
Those projects expose the central risk behind the round. Software can improve scheduling, equipment utilization and process control, but Mariana still faces construction, commissioning, commodity-price and operating risks that cannot be financed or coded away. Copper One must scale an existing operation, while Lithium One must bring a new processing facility into commercial production.
The Series B gives Mariana the balance sheet to run both tests at once. It also raises the standard of proof. After $310 million of new financing, investors will be measuring Caldwell's thesis in tonnes of copper and lithium produced, project schedules met and operating costs reduced.