Mariana Minerals Raises $310 Million Series B Led by Khosla Ventures to Accelerate Critical Minerals Production

The round funds the expansion of its portfolio of critical minerals projects and further deployment of its software platform, MarianaOS.

SAN FRANCISCO, Aug. 3, 2026 /PRNewswire/ -- Mariana Minerals ("Mariana"), a software-first, vertically integrated critical minerals company, today announced it has raised $310 million in Series B financing. The round was led by Khosla Ventures, with continued support from Andreessen Horowitz (a16z) and Breakthrough Energy Ventures, and new participation from Greenoaks, Halo Fund, Pax Ventures, StepStone Group, BHP Ventures, Washington Harbour Partners, Greycroft, General Innovation Capital Partners, Mitsubishi Corporation, In-Q-Tel (IQT), and Earthshot Ventures, with a number of additional strategic capital partners joining the round. This round brings the company's total parent and project capital raised to date to approximately $400 million.

Mariana engineers, builds, and operates mines and refineries using its proprietary MarianaOS platform, which integrates capital project execution (CapitalProjectOS), refinery operations (PlantOS), and mine management (MineOS) into a single AI and machine learning stack. MarianaOS compresses traditional 5-to-10 year project execution timelines by roughly half and reduces commissioning timelines well below industry benchmarks.

Mariana's Series B financing unlocks continued buildout of the company's active project portfolio, including its flagship sites Copper One in Southeastern Utah and Lithium One in East Texas. Copper One, acquired by Mariana in late 2025, restarted mining operations under autonomous orchestration within 4 months and is ramping toward a production target of 50,000 metric tons of refined copper per year. Lithium One, which broke ground in Q4 2025, is the world's first GWh-scale facility for producing lithium from oil & gas produced water, with commercial production targeted for the first half of 2027.

"Critical minerals are the materials that decide whether America builds its own future or keeps depending on China to build it instead. We backed Mariana because Turner is the kind of operator who can actually build and run AI-driven mines and refineries, faster and cleaner than anyone thought possible," said Vinod Khosla, founder of Khosla Ventures. "The minerals are there. What's been missing is the will and the AI to run mining and refining autonomously. That's exactly what Turner's team is building and why we backed them from day one."

This financing accelerates the company's goal of developing 10 commercial-scale projects in 10 years to strengthen domestic supply of critical minerals. Mariana's project portfolio is designed to be catalytic: each project generates operational data that improves MarianaOS, reducing the cost and time to build and operate the next facility.

"The critical minerals race is an execution problem, and we've spent the last two years proving that better software changes the math," said Turner Caldwell, CEO and Co-Founder of Mariana Minerals. "This additional capital lets us move from proving the model to scaling it; the time to build an autonomy-first minerals company, one that actually moves the needle on supply, is now."

About Mariana Minerals
Mariana Minerals is a software-first, vertically integrated critical minerals company that builds and operates mines and refineries across the metals that the modern economy depends on. For more information, visit marianaminerals.com.

SOURCE Mariana Minerals