The Largest Reported Borate Resource in the United States
Fort Cady's high-grade colemanite deposit underpins a multi-generational boron supply, with 28.3 million short tons of measured and indicated boric acid resources and proven mineral reserves supporting a 39.5-year initial mine life.
The Fort Cady Project contains 28.3 million short tons of measured and indicated boric acid resources at a grade of 8.09% B₂O₃, making it the largest reported borate resource in the United States. Mineral reserves total 5.4 million short tons of boric acid at 8.03% B₂O₃, supporting a 39.5-year Phase 1 mine life under the August 2025 SK-1300 Pre-Feasibility Study.
Resource & Reserve Summary
All estimates prepared under SEC Regulation SK-1300 by independent qualified persons. Resource estimates current as of November 15, 2025; reserve estimates current as of August 4, 2025.
61% Resource Upgrade
In November 2025, 5E Advanced Materials announced a substantial upgrade to the Fort Cady mineral resource estimate. Total measured and indicated boric acid resources increased 61%, from 17.5 million short tons to 28.3 million short tons, confirming Fort Cady as the largest reported borate resource in the United States.
The upgrade was driven by expanded drilling data and refined geological modeling, and represents the resource on lands under 5E's mineral control. Lithium resources also increased 54% alongside the borate upgrade.
What Changed
| Metric | PFS (Aug 2025) | Upgraded (Nov 2025) | Change |
|---|---|---|---|
| M+I Boric Acid (tons) | 15.09M | 28.3M | +61% |
| M+I B₂O₃ Grade | 7.89% | 8.09% | +0.20 pts |
Fort Cady Mineral Resources
Mineral resources estimated using a 2.0% B₂O₃ cut-off grade, constrained assuming in-situ leaching methods. Resources are reported on lands under 5E's current mineral control.
| Classification | Short Tons (M) | B₂O₃ Grade (%) | B₂O₃ (M tons) | H₃BO₃ (M tons) |
|---|---|---|---|---|
| Measured | 23.50 | 7.91 | 1.84 | 3.26 |
| Indicated | 85.63 | 7.89 | 6.66 | 11.83 |
| Total Measured + Indicated | 109.13 | 7.89 | 8.50 | 15.09 |
| Inferred | 4.26 | 7.45 | 0.31 | 0.55 |
1. Independently prepared by Steven Kerr, P.G., C.P.G., Escalante Geological Services, LLC, in accordance with SK-1300.
2. Completed using a gridded seam model with Carlson Mining™ software.
3. Resources current as of March 10, 2025 (PFS); updated to November 15, 2025 (resource upgrade).
4. Reported at a cutoff grade of 2.0% B₂O₃ assuming in-situ leaching mining methods.
5. Only resources on lands under current mineral control are reflected in the mine plan.
Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. Inferred resources are excluded from the production schedule and economic analysis.
Fort Cady Mineral Reserves
Mineral reserves derived from the Phase 1 mine plan, converting 41% of the measured and indicated resource. Reserves support a 39.5-year mine life producing 130,000 short tons per year of boric acid.
| Classification | Avg B₂O₃ Grade (%) | B₂O₃ (M tons) | H₃BO₃ (M tons) |
|---|---|---|---|
| Proven | 8.03 | 0.76 | 1.35 |
| Probable | 8.03 | 2.24 | 3.98 |
| Total Reserves | 8.03 | 3.00 | 5.33 |
1. Independently prepared by Alan White, P.E., Miocene, Inc., in accordance with SK-1300.
2. Based on a 2.0% B₂O₃ cut-off grade. Mining recovery: 81.9%, mining efficiency: 95.0%, process recovery: 95.1%.
3. Reserves are a subset of Measured and Indicated Resources; excludes Inferred Resources and areas without mineral tenure.
4. Current as of August 4, 2025.
Reserve Recovery Assumptions
| Mining Recovery (in-situ) | 81.9% |
| Mining Efficiency (drilling) | 95.0% |
| Processing Recovery | 95.1% |
| Cut-off Grade | 2.0% B₂O₃ |
Understanding the Fort Cady Colemanite Deposit
The Fort Cady boron resource is hosted in colemanite, a calcium borate mineral that formed from lacustrine (ancient lakebed) sediments. The deposit is continuous, fixed in place, and distinct from surrounding geological formations, properties that make it ideal for in-situ leaching recovery.
The mineralization occurs across three horizons at depth:
Upper Mineralized Horizon UMH |
Shallowest zone; accessible via directional wells |
Major Mineralized Horizon MMH |
Primary production target; highest grade and thickness |
Lower Mineralized Horizon LMH |
Deepest zone; targeted by extended lateral wells |
The deposit's depth precludes conventional open-pit or underground mining. 5E's in-situ leach approach dissolves the colemanite in place using heated leach solution, then recovers the boron-rich solution at the surface, the same principle validated during the 1980s and 1990s pilot operations and now confirmed by the current small-scale facility.
Significant Expansion Optionality
The current PFS mine plan converts only 41% of the measured and indicated resource into mineral reserves. This means the remaining resource base provides substantial upside for future expansion phases, additional production tonnage, and value-added boron derivative products.
In July 2025, 5E staked additional lode claims for remaining open colemanite mineralization areas. In August 2025, these claims were filed with the United States Bureau of Land Management, further expanding the company's mineral tenure and positioning the resource for long-term development.
SK-1300 Compliance & Qualified Persons
All mineral resource and reserve estimates at Fort Cady have been independently prepared under SEC Regulation SK-1300, the United States standard for mining property disclosure.
Technical Report
The Pre-Feasibility Study, titled "Preliminary Feasibility Report & Technical Report Summary, 5E Advanced Materials Fort Cady Project," dated August 7, 2025, was prepared under SEC S-K regulations, Title 17, Part 229, Items 601 and 1300 through 1305.
The report is available on the SEC's EDGAR website as Exhibit 96.1 to the Company's Form 8-K filed on August 7, 2025.
Qualified Persons
| Person | Firm | Responsibility |
|---|---|---|
| Alan White, P.E. | Miocene, Inc. | Mineral Reserves |
| Steven Kerr, P.G., C.P.G. | Escalante Geological Services | Mineral Resources |
| Fluor Corporation | Engineering & Capital Costs | |
| Geomega, Inc. | Technical Support | |
| Paul Weibel, CEO | 5E Advanced Materials | Market Strategy & Economic Assumptions |
Resource & Reserves FAQ
As of November 2025, Fort Cady contains 28.3 million short tons of measured and indicated boric acid resources at a grade of 8.09% B₂O₃. This makes it the largest reported borate resource in the United States and the largest known new conventional boron deposit outside of Turkey.
Mineral resources represent the total estimated mineral endowment that has reasonable prospects for economic extraction. Mineral reserves are the subset of resources that have been confirmed as economically mineable through a detailed mine plan and feasibility study. At Fort Cady, the Phase 1 mine plan converts 41% of the measured and indicated resource into 5.4 million tons of proven and probable boric acid reserves.
All mineral resource and reserve estimates are prepared under SEC Regulation SK-1300, the U.S. standard for mining property disclosure. Estimates were independently prepared by qualified persons at Escalante Geological Services (resources) and Miocene, Inc. (reserves).
The 61% increase in measured and indicated boric acid resources, from 17.5 million to 28.3 million short tons, was driven by expanded drilling data, refined geological modeling, and the inclusion of newly staked lode claim areas. The upgrade applied to resources only; PFS mineral reserves and project economics remain unchanged.
Yes. The current mine plan converts only 41% of the measured and indicated resource. The remaining 59% provides significant optionality for future expansion phases, additional production tonnage, and potential downstream boron derivative products. The company also staked additional lode claims in 2025 to expand mineral tenure.
Cautionary Note
Mineral resource and reserve estimates are inherently subject to uncertainty and are based on assumptions regarding geological continuity, cut-off grades, mining methods, and economic conditions. Inferred mineral resources are not Mineral Reserves and do not have demonstrated economic viability. There is no assurance that resources will be converted to reserves or that expansion phases will proceed. For complete risk factors, see the Company's SEC filings. The Pre-Feasibility Study is available as Exhibit 96.1 to Form 8-K filed August 7, 2025.
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