Funding

Critical Minerals Startup Mariana Minerals Scores $310M in Series B Funding

Aug 4, 2026 | By Devin Jacobs

SUMMARY

Mariana Minerals raised $310 million in Series B funding.
Mariana Minerals develops AI-powered critical mineral mining solutions.
The funding will expand its projects and support future growth.

Mariana Minerals, a San Francisco, CA-based provider of a software-first, vertically integrated critical minerals platform, has raised $310 million in a Series B financing round led by Khosla Ventures, bringing the total to approximately $ 400 million.

The round also saw participation from Andreessen Horowitz (a16z), Breakthrough Energy Ventures, Greenoaks, Halo Fund, Pax Ventures, StepStone Group, BHP Ventures, Washington Harbour Partners, Greycroft, General Innovation Capital Partners, Mitsubishi Corporation, In-Q-Tel (IQT), Earthshot Ventures, and additional strategic capital partners.

The latest funding will help Mariana Minerals expand its project portfolio and advance its goal of developing 10 commercial-scale critical minerals projects over 10 years.

Funding Snapshot

Metric	Details
Fundraise Amount	$310 million
Funding Round	Series B
Valuation	Undisclosed
Total Funding	Approximately $400 million
Company	Mariana Minerals
Sector	Critical Minerals / Mining Technology
Headquarters	San Francisco, California, US

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About Mariana Minerals

Founded by Turner Caldwell and Juan Lozano, Mariana Minerals is a software-first, vertically integrated critical minerals company developing and operating mines and refineries.

The company combines physical mining infrastructure with AI, machine learning and proprietary software to accelerate the development and operation of critical mineral projects.

Core offerings include:

Critical mineral mining
Mineral refining
AI-powered mine management
Automated project execution

Core Technologies / Products / Services

Capability/Product	Application/Use Case
MarianaOS	AI and machine learning platform for mining and refining
CapitalProjectOS	Capital project execution
PlantOS	Refinery operations management
MineOS	Mine management and operations

Leadership Comments

"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."

"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.