Gunnison’s rich copper-zinc hit in Arizona: processing options for mine planners
Reviewed by Joe Ashwell

First reported on MINING.com
30 Second Briefing
Gunnison Copper has confirmed a high-grade copper-zinc zone at the Strong & Harris deposit in Arizona, with drill hole SHM-2 cutting 94.8 metres at 1.39% Cu and 2.29% Zn from 160 metres depth, including 12.2 metres at 5.15% Cu, 11.99% Zn and 16.38 g/t Ag. The company will run flotation tests on sulphide material to determine recoveries and economics for potential copper and zinc concentrates, as an alternative to the current heap leach–SX–EW flowsheet in its March PEA. Gunnison is already producing copper at nearby Johnson Camp using Rio Tinto’s Nuton leaching technology under an $8 million demonstration agreement running to 2029.
Technical Brief
- Gunnison estimates true thicknesses of 82.1 m for the main SHM-2 interval and 10.5 m for the higher-grade core.
- Strong & Harris hosts 69 Mt inferred at 0.49% Cu, 0.56% Zn and ~4.1 g/t Ag (January 2023).
- Contained metal in that inferred resource totals ~335,700 t Cu, 388,100 t Zn and 9 Moz Ag.
- Flotation testwork is specifically targeting sulphide material to generate saleable Cu and Zn concentrates with Ag credits.
- Any concentrator addition would modify the March PEA’s open-pit, heap leach–SX–EW copper-only flowsheet.
- Gunnison’s Johnson Camp operation is concurrently trialling Rio Tinto’s Nuton leaching technology under a 2027–2029 demonstration.
- Nuton agreed in September to pay Gunnison US$8 million (C$11.3 million) after expanding mined demonstration tonnage.
Our Take
Nuton’s earlier bioleach work at Johnson Camp, which delivered first 99.99% copper cathode by late 2025, means any additional sulphide or mixed mineralisation at Strong & Harris could be candidates for the same processing route, potentially lowering capex compared with a greenfield concentrator in Arizona.
With Amazon Web Services already lined up as an offtaker for Nuton‑produced copper from Johnson Camp, incremental copper units from the Gunnison project give Gunnison Copper and Rio Tinto more flexibility to structure premium, low‑carbon or technology‑linked copper cathode supply contracts out of Arizona.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
Related Articles
Related Industries & Products
Mining
Geotechnical software solutions for mining operations including CMRR analysis, hydrogeological testing, and data management.
CMRR-io
Streamline coal mine roof stability assessments with our cloud-based CMRR software featuring automated calculations, multi-scenario analysis, and collaborative workflows.
HYDROGEO-io
Comprehensive hydrogeological testing platform for managing, analysing, and reporting on packer tests, lugeon values, and hydraulic conductivity assessments.
GEODB-io
Centralised geotechnical data management solution for storing, accessing, and analysing all your site investigation and material testing data.


