Operations & Administrative Assistant (Part-Time)

Mafix • Seattle, WA

4d • Onsite

About The Position

Mafix transforms the world's most abundant rocks and minerals into the next generation of fertilizers. Our products help farmers maintain and improve crop yields while permanently removing CO₂ from the atmosphere through enhanced rock weathering, delivering a dual return that conventional agricultural products cannot. We produce our mineral fertilizer using spare capacity in cement rotary kilns, making it cost-competitive without building new infrastructure. Applied to soil, it releases plant-available silicon and other nutrients that strengthen crops against climate stress, drought, and pests, while sequestering carbon as the mineral dissolves. With core chemistry published in Nature, our pre-seed funding secured, and key partnerships in place, we are scaling fast: moving from pilot production to a 1,000-tonne commercial run in 2027. We are looking for team members excited to unlock the power of abundant rocks towards a climate positive and food abundant future! We are looking for a reliable, resourceful, and detail-oriented Administrative Assistant to keep our Seattle office and lab running smoothly. This is a hands-on, in-person role supporting day-to-day operations for a small, fast-moving team. You'll be the person who makes sure supplies are stocked, shipments are received, vendors are paid, and the small things that keep a startup humming don't slip through the cracks.

Requirements

• 2+ years of administrative, operations, or office coordination experience, ideally in a startup, lab, or small-business setting.
• Highly organized and self-directed, with strong attention to detail and follow-through.
• Comfortable juggling varied tasks and shifting priorities.
• Proficient with common office and productivity tools (email, calendars, spreadsheets, document sharing).
• Reliable, discreet, and able to work independently in person in Seattle, WA.

Nice To Haves

• Experience with basic bookkeeping or procurement a plus.

Responsibilities

• Manage office and lab logistics: order supplies and equipment, receive and log shipments, and coordinate with vendors.
• Support facilities upkeep and coordinate with building management and service providers.
• Assist with bookkeeping tasks such as expense tracking, invoice processing, and receipt organization.
• Help schedule meetings, coordinate travel, and support team onboarding.
• Keep records, files, and shared systems organized and up to date.
• Pitch in wherever needed to keep a growing team running efficiently.

What This Job Offers

• Job Type: Part-time
• Career Level: Entry Level
• Education Level: No Education Listed