Mechanical Engineer

Department: Process Development

Location: San Francisco HQ

Compensation: $100K – $150K • Offers Equity

Employment Type: FullTime

About Mariana Minerals

Mariana Minerals is a software-first, vertically integrated minerals company on a mission to supply the critical minerals powering modern energy, AI, and defense technologies. We’re reimagining the minerals supply chain by combining deep industry expertise with advanced software, automation, and data-driven decision-making.

The Role

Mariana Minerals is looking for a highly motivated Mechanical Engineer to join our San Francisco Pilot Plant team. You will support the design, installation, and maintenance of first-of-its-kind refining processes for critical minerals. This position plays a critical role in bridging R&D and Operations, ensuring our equipment and work processes are robust, safe, cost-effective, and suitable for commercial production.

What You'll Do

• Drive design, fabrication, installation, modification, startup, and commissioning of new equipment and pilot plant systems.

• Troubleshoot mechanical issues and implement practical solutions to maintain safe, reliable, and efficient plant operations.

• Work closely with process engineers and R&D scientists to translate process requirements into equipment modifications, mechanical designs, and plant improvements.

• Create and maintain engineering documentation, including P&IDs, process and control narratives, equipment specifications, drawings, CAD models, and equipment manuals.

• Identify opportunities to improve equipment reliability, maintainability, and operational performance

• Support the development of software and to help drive rapid equipment design, plant reliability, and safe operation

• Travel to Mariana sites to support new projects, start-up/commissioning, and troubleshooting initiatives

What You'll Bring

• B.S., M.S., or PhD in Mechanical Engineering or a related field

• Experience in automated manufacturing, operations, process scale-up, or plant design in minerals processing, chemicals, specialty materials, oil & gas, or related industries

• Demonstrated experience driving equipment design, commissioning, operations, and reliability

• Ability to wear multiple hats and take on additional scope in areas such as process engineering, operations, maintenance, and project execution

• Strong troubleshooting and problem-solving skills in hands-on plant environments

• Strong commitment to Health, Safety, and Environmental compliance and mechanical integrity standards

• Excellent technical writing, communication, and teamwork skills

• Comfortable working in fast-paced environments and managing ambiguity

Our culture is built on four principles:

Everyone Gets Home Safe. We never put speed or cost ahead of people.

Extreme Ownership. We take full responsibility for outcomes, relentlessly driving toward solutions.

Engineer Out Requirements, then Automate. We simplify, optimize, and then automate for scale.

Share Your Legos. We collaborate openly, share knowledge, and empower each other to build bigger, better solutions.

Join us as we build the future of responsible mineral sourcing and supply!