Gunnison Copper Reports Positive Results from Initial Mineral Sorting "High-Value-Add" Work Program at the Gunnison Copper Project in Southeast Arizona
Sorting Tests Reduced Acid Consumption, a Key Operating Cost Driver, on the Highest Acid Consuming Mineralized Material by Approximately 75% While Maintaining Copper Recovery
Phoenix, Arizona--(Newsfile Corp. - September 15, 2025) - Gunnison Copper Corp. (TSX: GCU) (OTCQB: GCUMF) (FSE: 3XS0) ("Gunnison" or the "Company") is pleased to announce encouraging results from its initial mineralized material sorting test program at the flagship Gunnison Copper Project in southeast Arizona, one of the largest and most advanced copper development projects in the United States.
"These initial results are extremely encouraging, showing the potential to significantly reduce acid consumption while maintaining copper recovery," stated Roland Goodgame, Gunnison's SVP of Business Development. "This type of high-value-add program can materially improve the Project's already robust economics and feed directly into our upcoming update to our preliminary economic assessment and planned pre-feasibility study. These results support Gunnison's vision of producing cost-effective, sustainable, and 100% Made-in-America copper."
Initial Mineralized Material Sorting Results:
- Sample: A half-ton sample consisting of 2" to 6" pieces of PQ drill core from the Martin Formation, collected as part of Gunnison's recently completed metallurgical drilling program. The Martin Formation is the highest acid consuming rock type in the deposit and makes up ~44% of the resource base. The sample was comprised of ~54% mineralized material and ~46% internal waste, consistent with the overall Martin Formation.
- Waste Reduction: Over 90% of the internal acid-consuming waste was successfully removed from the mineralized material using optical mineral sorting equipment at a commercial scale.
- Acid Consumption Reduction: Due to the removal of the high-acid-consuming waste, the sorted material is expected to require up to 4x lower acid consumption.
- Copper Recovery: Less than 1% of total copper was lost to waste, ensuring strong copper recovery and protecting revenue.
- Testing Location: Initial sorting tests were conducted at Steinert's facilities in Kentucky in August 2025.
Table 1: Results of mineral sorting test work on the Martin Formation from the Gunnison Open Pit resource. 57% of the sample sorted to mineralized and 43% sorted to waste.
Should further test work remain consistent with the initial testing results, it suggests approximately 40% of the mined Martin Formation can be removed as internal waste by optical mineral sorting prior to processing on the leach pad. This would result in a near doubling of the process head grade, and significantly reduced process operating costs.
Next Steps:
- Optimization testing on different size fractions of the Martin formation
- Mineral Sorting samples will be crushed at Base Metallurgical Labs in Tucson.
- Crushed materials will then be returned to Steinert for further mineral sorting tests to determine further liberation and sizing characteristics.
- Following the mineralization being separated from internal waste, column leach testing will be conducted on sorted products.
- Some samples may be sent to Germany for testing using Steinert's advanced M Sorters.
- Incorporating results into updated PEA expected in the first quarter of 2026.
About Mineralized Material Sorting:
Copper oxide exists on visually distinct blue-green and red-brown zones that are ideally suited to optical mineralized material sorting. Preliminary testing was 100% successful and data suggest sorting of this material has the potential to greatly reduce acid consumption and volume of material leached by removing 40 to 50 percent of the process stream as unmineralized, higher acid consuming, waste (See Figure-1). This would result in significant savings on operating costs.
