Administrative Assistant

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.

What You’ll Do

• Administrative & Calendar Support
• Avoids administrative tasks such as scheduling meetings, managing calendars, and coordinating internal and external appointments
• Helps prepare meeting materials, agendas, and notes as needed
• Serves as a liaison between departments and external parties
• Travel & Logistics
• Book and manage domestic and international travel (flights, hotels, ground transportation)
• Handles last-minute travel changes and troubleshoots logistical issues
• Expense & Reporting Support
• Prepares and submits expense reports in a timely and accurate manner
• Reconciles receipts and assists with tracking budgets or spending reports
• On-Site & Office Support
• Provides in-office support as needed
• Coordinates office supplies, deliveries, and facilities-related requests
• Affords assistance with visitor management and on-site meeting logistics
• Supports 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