Administrative Assistant

Mariana MineralsMariana 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 RoleWe 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 DoAdministrative & Calendar SupportAssist with scheduling meetings, managing calendars, and coordinating internal and external appointmentsHelp prepare meeting materials, agendas, and notes as neededSupport coordination of cross-functional meetings and company eventsTravel & LogisticsBook and manage domestic and international travel (flights, hotels, ground transportation)Handle last-minute travel changes and troubleshoot logistical issuesExpense & Reporting SupportPrepare and submit expense reports in a timely and accurate mannerReconcile receipts and assist with tracking budgets or spending reportsOn-Site & Office SupportProvide in-office support as neededCoordinate office supplies, deliveries, and facilities-related requestsAssist with visitor management and on-site meeting logisticsSupport internal events and team off-sitesExecutive Assistant BackupServe as backup to the Executive Assistant during absencesProvide overflow support during high-volume periodsAssist with special projects and ad hoc requestsDesired Qualifications1–3+ years of administrative or office support experience preferredStrong organizational skills and attention to detailExcellent written and verbal communication skillsProficiency in Microsoft OfficeExperience with expense management and calendar systems preferredAbility to handle confidential information with discretionStrong time management and prioritization skillsProblem-solving mindsetProfessional and service-oriented approachAdaptability in a fast-paced environmentTeam player with a positive attitudeOur Culture Is Built On Four PrinciplesEveryone 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!