Administrative Assistant

Mariana Minerals; Houston (TX); On-site; USD 34,000 - 52,000; Full time

Job summary

Mariana Minerals in Houston invites an Administrative Assistant to support the CFO with calendar management, travel planning, and expense processing, while also assisting with day-to-day office operations.

The role requires 1–3+ years of administrative experience, strong communication, and excellent organization in a fast-paced environment. The position also supports the Executive Assistant during peak periods and may involve event coordination.

Qualifications

• 1–3+ years of administrative or office support experience
• Excellent written and verbal communication skills
• Strong organizational skills and attention to detail
• Proficiency in Microsoft Office
• Experience with expense management and calendar systems
• Ability to handle confidential information with discretion
• Strong time management and prioritization skills
• Professional and service-oriented approach
• Adaptability in a fast-paced environment
• Team player with a positive attitude

Responsibilities

• Provide administrative support to the CFO, including calendar and travel coordination and expense management
• Coordinate domestic and international travel, flights, hotels, and ground transportation
• Prepare and submit expense reports and reconcile receipts
• Support day-to-day office operations and visitor management
• Act as backup to the Executive Assistant during absences and high-volume periods

Skills

Organizational skills

Written & verbal communication

Time management

Tools

Microsoft Office

Job description

About Mariana Minerals

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!