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 an experienced Accounts Payable Manager to lead Mariana Minerals’ accounts payable operations and help build a scalable, technology-enabled procure-to-pay function. This position is responsible for ensuring the timely and accurate processing of supplier invoices, compliance with company purchasing policies and internal controls, and leading a high-performing AP team.

The ideal candidate combines strong operational accounting experience with a continuous-improvement mindset and enjoys building efficient processes that leverage automation. As Mariana continues to grow, this role will play a key part in implementing best-in-class procure-to-pay practices, improving vendor relationships, strengthening internal controls, and supporting the company’s readiness for continued growth.

This role will work closely with Procurement, Operations, Accounting, Treasury, FP&A, and business leaders across multiple operating locations.

What You’ll Do

Accounts Payable Operations

• Supervise and assist in the daily processing of vendor invoices across multiple legal entities.

• Ensure invoices are processed accurately, completely, and in accordance with company policies and payment terms.

• Ensure three-way matching of purchase orders, goods receipts, and vendor invoices.

• Review invoice coding for accuracy, including general ledger accounts, departments, projects, entities, and budget classes.

• Manage invoice queues and ensure service-level expectations for invoice processing are achieved.

• Coordinate weekly payment proposals with Treasury while supporting working-capital objectives and vendor relationships.

• Monitor accounts payable aging and proactively

Vendor Management

• Serve as the primary escalation point for vendor inquiries, account statements, and payment disputes.

• Build strong relationships with key suppliers while ensuring consistent communication regarding payment status.

• Coordinate the resolution of invoice discrepancies with Procurement and operational teams.

• Oversee vendor onboarding documentation, including W-9 or W-8 forms, banking information, tax forms, certificates of insurance, and other required support.

• Prepare and complete vendor credit applications to establish or expand supplier credit terms.

• Assist in maintaining an accurate vendor master and support vendor due-diligence processes.

Invoice Approvals and Exception Management

• Supervise, coach, mentor, and develop Accounts Payable staff.

• Establish performance expectations and monitor individual and team productivity, quality, and timeliness.

• Conduct regular performance reviews and provide ongoing feedback and coaching.

• Develop cross-training plans to ensure operational continuity and appropriate coverage.

• Promote a culture of customer service, accountability, collaboration, and continuous improvement.

Team Leadership

• Supervise, coach, mentor, and develop Accounts Payable staff.

• Establish performance expectations and monitor individual and team productivity, quality, and timeliness.

• Conduct regular performance reviews and provide ongoing feedback and coaching.

• Develop cross-training plans to ensure operational continuity and appropriate coverage.

• Promote a culture of customer service, accountability, collaboration

Process Improvement and Internal Controls

• Identify opportunities to automate invoice processing, approval workflows, and exception handling.

• Support the implementation and optimization of AP automation tools, OCR technologies, and ERP workflows.

• Develop and maintain standard operating procedures, desk procedures, and process documentation.

• Ensure compliance with internal controls, segregation of duties, procurement policies, and payment authorization requirements.

• Support internal and external audit requests and remediation activities.

• Monitor key performance indicators and recommend

Reporting and Analytics

• Prepare and report key Accounts Payable metrics, including:

• Invoice processing cycle time and backlog

• Percentage of invoices supported by purchase orders

• Outstanding approval aging

• Vendor aging

• Non-PO invoice volume

• Provide regular reporting and recommendations to Finance leadership to improve operational efficiency and support decision-making.

Desired Qualifications

• Bachelor’s or Associate’s degree in Accounting, Finance, Business Administration, or a related field

• Five or more years of progressive Accounts Payable experience, including at least two years supervising or leading AP staff

• Experience in manufacturing, mining, energy, industrial, construction, or another asset-intensive industry is preferred

• Strong understanding of procure-to-pay processes, invoice matching, vendor management, and payment controls

• Experience with ERP systems such as Odoo, NetSuite is preferred

• Experience with AP automation platforms and OCR technologies is highly desirable

• Strong knowledge of internal controls, segregation of duties, and financial compliance

• Experience implementing process improvements and automation initiatives

• Excellent organizational skills and the ability to manage competing priorities in a fast-paced environment

• Strong analytical, problem-solving, interpersonal, and communication skills

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!