Introduction
The Sombrero Butte Project is a 100% owned, early-stage porphyry copper exploration target located in the Bunker Hill Mining District, Pinal County, Arizona, approximately 3km south of Faraday Copper’s Copper Creek porphyry copper project, a develpment-stage asset with a large copper resource and a robust PEA. The Copper Creek porphyry hosts a Measured and Indicated resource of 4.2Blb of copper and 544Mlb of molybdenum, and its 2023 PEA outlines a 30-year mine life with an after-tax NPV 7% of US$713M, an IRR of 16% at $3.75/lb copper. This underscores the regional potential and validates Sombrero Butte’s proximity to a large porphyry copper deposit.
Sombrero Butte shares a nearly identical geological setting to Copper Creek, including Laramide age multiphase intrusives, widespread breccia pipe hosted mineralization (with over 120 pipes mapped) and similar structural controls. Historical high-grade copper production and a recently defined chargeability anomaly suggests potential for a deeper porphyry system, making Sombrero Butte a highly prospective exploration asset in a Tier 1 mining jurisdiction.
Geology & Mineralization
Sombrero Butte is underlain by the Laramide aged multiphase Copper Creek intrusive complex, geologically equivalent to the host rocks at the nearby Copper Creek deposit. The property is characterized by a cluster of magmatic-hydrothermal breccia pipe swarms, which have historically returned high copper grades, with some mined material averaging up to 5% copper. These breccia pipes are interpreted as indications of a deeper porphyry centrer, serving as vertical conduits for metal-bearing fluids rising from a larger mineralized system at depth.
To date, 34 historical drillholes totalling 6,435m have been completed, primarily targeting the higher-grade copper mineralization in the near-surface breccia pipes. Results include standout intercepts such as DDH SB-07-14, which returned 1.16% copper over 86m from surface, along with several other holes exceeding 1% copper across meaningful widths, highlighting the strength and consistency of the breccia-hosted mineralization and supporting the interpretation of a buried porphyry at depth.
Property Description
In 2012 Copper Fox purchased a 100% working interest in the Sombrero Butte project. The project consists of three Arizona Mineral Exploration Permits, 77 BLM mining claims and two patented mining claims covering approximately 1,389 ha. In October 2021 Copper Fox made their final option payment to own a 100% interest in certain unpatented and patented mining claims.
2024-2025 Exploration
During 2024 and early 2025, Copper Fox focussed on evaluating the porphyry copper potential of the project. The program included mapping, alteration and geochemical data and geophysical surveys. The program defined a large, highly evolved, deep, porphyry copper target that exhibits indicators of ‘hypogene enrichment’ of the copper mineralization and superimposed hydrothermal events. The features typical of a porphyry copper system located within the copper target are outlined below:
- The project geology consists of Laramide age Glory Hole volcanics and porphyritic and non-porphyritic phases of the Copper Creek granodiorite and occupies the same structural setting as the Copper Creek porphyry copper deposit.
- The chargeability anomaly (>25mrad) measures approximately 3,200m long by 1,300m wide and is interpreted to extend to depths of more than 1,200m below surface.
- An inner zone of potassic alteration surrounded by widespread phyllic (quartz-pyrite (limonite)-sericite) and distal advanced argillic, prophylitic and tourmaline alteration occur within the chargeability anomaly.
- Petrographic and mineralogical studies identified several examples of ‘hypogene enrichment’ (i.e. bornite rimming chalcopyrite), magnetite rimming pyrite suggesting several superimposed high temperature hypothermal events and the presence of hypersaline fluid inclusions with liquid + vapor + solid phases of halite, hematite, chalcopyrite and anhydrite typically observed in porphyry copper deposits.
- Five different styles of mineralized and non-mineralized breccia pipes occur within the chargeability anomaly.
- Several areas of thermal metamorphism of the Glory Hole volcanics have been identified, suggesting a relatively thin cover of Glory Hole volcanics underlian by the Copper Creek granodiorite intrusive.
In 2024, DCIP and magnetotelliric (MT) geophysical surveys mapped the chargeability signature to a depth of 600-700m and resistivity signature to depth of +/- 1,500m below surface. The chargeability/resistivity anomaly (>25mrad) outlined by the surveys measures approximately 3,200m long by 1.300m wide and extends from surface to a depth in excess of 1,200m below surface based on the MT data.
Porphyry Footprint
The porphyry footprint exhibits a strong spatial correlation to the underlying chargeability/resistivity anomaly. The anomaly is hosted in Laramide age Glory Hole volcanics and younger Copper Creek granodiorite, a composite, weakly peraluminous to metaluminous calcalkaline intrusive and shares the same regional scale structural setting as the Copper Creek porphyry copper deposit.
Copper-molybdenum mineralization is hosted in steeply dipping, northeast trending quartz veinlets, fractures, breccia pipes with lesser amounts of disseminated chalcopyrite in the Copper Creek intrusive. The Glory Hole volcanics is characterized by a large zone of moderate to intense limonite staining interpreted to be due to the weathering/oxidization of quartz-pyrite-sericite veinlets typically observed in the phyllic alteration zone.
Within the porphyry footprint, five different styles of mineralized and non-mineralized breccia pipes exhibiting distinct geochemical signatures and alteration patterns occur; all of which are interpreted to be due to magmatic hydrothermal processes related to the porphyry copper system.