--- title: 'Administrative Assistant at Mariana Minerals' canonical: 'https://feeny.ai/job/administrative-assistant-mariana-minerals-houston-bamf8ahyve5k' type: 'job' last_seen: '2026-09-04' --- # Administrative Assistant at Mariana Minerals - **Company:** Mariana Minerals - **Location:** Houston, TX - **Compensation:** $60k–$85k - **Employment:** full-time - **Work type:** onsite - **Posted:** 2026-08-26 - **Last confirmed live:** 2026-09-04 - **Apply:** https://jobs.ashbyhq.com/marianaminerals/42d74030-792c-44d6-9d93-6c0623d19cf7 ## Job description ## 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 We are seeking a highly organized and proactive Administrative Assistant to support day-to-day administrative operations at our Houston office. This role is ideal for someone early in their career who is detail-oriented, resourceful, and eager to grow within an operations or executive support function. The Administrative Assistant will provide administrative support to the CFO, including calendar and travel coordination and expense management, while also supporting day-to-day office operations. The role will also serve as backup to the Executive Assistant as needed. This position requires strong communication skills, flexibility, sound judgment, and the ability to manage competing priorities in a fast-paced environment. ## WHAT YOU’LL DO Administrative & Calendar Support - Assist with scheduling meetings, managing calendars, and coordinating internal and external appointments - Help prepare meeting materials, agendas, and notes as needed - Support coordination of cross-functional meetings and company events Travel & Logistics - Book and manage domestic and international travel (flights, hotels, ground transportation) - Handle last-minute travel changes and troubleshoot logistical issues Expense & Reporting Support - Prepare and submit expense reports in a timely and accurate manner - Reconcile receipts and assist with tracking budgets or spending reports On-Site & Office Support - Provide in-office support as needed - Coordinate office supplies, deliveries, and facilities-related requests - Assist with visitor management and on-site meeting logistics - Support internal events and team off-sites Executive Assistant Backup - Serve as backup to the Executive Assistant during absences - Provide overflow support during high-volume periods - Assist with special projects and ad hoc requests ## DESIRED QUALIFICATIONS - 1–3+ years of administrative or office support experience preferred - Strong organizational skills and attention to detail - Excellent written and verbal communication skills - Proficiency in Microsoft Office - Experience with expense management and calendar systems preferred - Ability to handle confidential information with discretion - Strong time management and prioritization skills - Problem-solving mindset - Professional and service-oriented approach - Adaptability in a fast-paced environment - Team player with a positive attitude 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! ## About Mariana Minerals ## Company Overview - **One-liner**: Mariana Minerals is a software-first, vertically integrated minerals company focused on supplying the minerals critical to modern energy, AI, and defense technologies. - **Entity Type**: Private (Series A, $85M funding in July 2025) - **Headquarters**: San Francisco, California, United States - **Founded**: Not publicly available - **Founders**: Turner Caldwell (Co-Founder & CEO) ## Core Business - **Primary industry**: Metal Ore Mining / Critical Minerals - **Target customers**: B2B – energy, AI, and defense supply chains (including downstream manufacturers and government entities) - **Mission or purpose**: "Create a future of critical mineral abundance" by reimagining the global minerals supply chain with software, automation, and data-driven decision making. ## Products & Services - **Copper One (formerly Lisbon Valley Copper Mine)**: World’s first autonomous mine, located in Utah. Produces copper using integrated automation and software control. Restarted production in April 2026. - **Lithium One**: Lithium project (on the roadmap or early development). - **Other mineral projects**: Graphite, Uranium, Rare Earth Metals, Cobalt, Nickel, Aluminium – at various stages (stealth or roadmap). - **CapitalProjectOS**: Internal software platform for capital project management (mentioned in leadership bio). - **Technology Stack**: React, dbt, TypeScript, Python, TensorFlow, PyTorch, microservices, SCADA, Autodesk, and many others – indicating a strong software engineering backbone. ## Market Standing - **Valuation/Market Cap**: Not disclosed (private company) - **Key Metric**: Total funding – $85M Series A (July 2025, 1 investor) - **Notable Investors/Partners**: Lead investor not publicly disclosed (Andreessen Horowitz was pitched but not confirmed as an investor). Partners include Bot Auto, WeRide, Pronto, Atoms (based on LinkedIn mentions). Also works with UMA (Utah Mining Association). - **Growth Signals**: Headcount grew 3,575% YoY to 107 employees (as of mid-2026). 73 active job postings. Opened the world’s first autonomous mine (Copper One) in April/May 2026, generating significant industry news and social media engagement. ## Competitive Advantages - **Software-first approach**: The company builds automation and data systems from the ground up, rather than layering tech onto legacy mining operations. This enables fully autonomous mining. - **Vertical integration**: They develop, own, and operate mineral projects, controlling the entire value chain from extraction to processing. - **Deep tech stack**: Use of AI/ML (TensorFlow, PyTorch), simulation, and real-time control systems to optimize mining operations. - **First-mover in autonomous mining**: Copper One is claimed to be the world’s first autonomous mine, giving them a significant lead in operational efficiency and safety. ## Strategic Focus - Scale autonomous mining operations beyond copper (lithium, graphite, uranium, etc.) - Secure domestic supply of critical minerals for U.S. energy, AI, and defense needs. - Continue aggressive hiring across engineering, operations, and field roles. - Expand from Utah to additional sites (Houston engineering office, potential new projects). ## Why Work Here - **Culture principles**: "Extreme Ownership", "Engineer Out Requirements, Then Automate", "Share Your Legos" – emphasizing accountability, simplification, and collaboration. - **Work environment**: High-growth startup with a mission-driven focus on critical infrastructure. Offices in San Francisco (HQ), Houston (Engineering), and La Sal, Utah (mine site). Hybrid/remote policy not explicitly stated, but multiple office locations suggest flexibility for field vs. office roles. - **Notable perks**: Opportunity to work on cutting-edge autonomous systems and AI in a traditional industry. Strong engineering culture with modern tech stack (React, Python, ML). Rapid career growth due to company expansion. - **Talent sources**: Attracts talent from Tesla, Redwood Materials, Lilac, ExxonMobil, Amazon Web Services, and other tech/energy companies – indicating a high-caliber peer group. ## Sources 1. [marianaminerals.com](https://marianaminerals.com/) 2. [marianaminerals.com/careers](https://marianaminerals.com/careers) 3. [marianaminerals.com/about](https://marianaminerals.com/about) 4. [jobs.ashbyhq.com/marianaminerals](https://jobs.ashbyhq.com/marianaminerals) 5. [linkedin.com/company/mariana-minerals](https://www.linkedin.com/company/mariana-minerals) ## Other roles at Mariana Minerals - [Sr./Staff Technical Program Manager - Copper](https://feeny.ai/job/sr-staff-technical-program-manager-copper-mariana-minerals-moab-hybc9rnj2271) — Moab, UT - [Mechanical Engineer](https://feeny.ai/job/mechanical-engineer-mariana-minerals-san-francisco-dv7an46y7ypw) — San Francisco, CA - [Pilot Plant Technician (Night Shift)](https://feeny.ai/job/pilot-plant-technician-night-shift-mariana-minerals-san-francisco-xt80rkhtfgne) — San Francisco, CA - [Full Stack Software Engineer](https://feeny.ai/job/full-stack-software-engineer-mariana-minerals-san-francisco-tdera62xv3p5) — San Francisco, CA - [Senior Systems Administrator](https://feeny.ai/job/senior-systems-administrator-mariana-minerals-san-francisco-t93c8xavrzp1) — San Francisco, CA - [Lead Operator](https://feeny.ai/job/lead-operator-mariana-minerals-east-6239emcdyrrk) — East, TX - [Lab Chemist](https://feeny.ai/job/lab-chemist-mariana-minerals-moab-3s3trq9bcdc4) — Moab, UT - [Controls Technician](https://feeny.ai/job/controls-technician-mariana-minerals-east-kt73j4cf89md) — East, TX - [Maintenance Technician](https://feeny.ai/job/maintenance-technician-mariana-minerals-east-am22rcspy7bp) — East, TX - [Process Engineer](https://feeny.ai/job/process-engineer-mariana-minerals-east-en510gjggana) — East, TX