Desert Fox Sombrero Butte Co., a wholly owned subsidiary of Copper Fox Metals Inc. owns a 100% working interest in the Sombrero Butte project which covers 2,913 acres located in the Copper Creek District (formerly known as the Bunker Hill District) 44 miles northeast of Tucson, Arizona. The project is located within sight of the former BHP San Manuel-Kalamazoo copper smelter and mine (production of 10.4 billion pounds (“lbs”) Cu), and 2 miles south of Redhawk Resources’ Copper Creek deposit. The Copper Creek deposit is hosted in the Copper Creek Granodiorite. The surface expression of the Copper Creek deposit is a significant number of mineralized breccia pipes. The property was previously mined for high grade copper from the breccia pipes on a limited basis in the past.
The Sombrero Butte project is located in the prolific Laramide age porphyry copper belt that hosts numerous large porphyry copper mines in Arizona. Arizona is mining friendly; politically secure with excellent and readily accessible infrastructure.
The geology of the Sombrero Butte project comprises lithologic units ranging from Pre-Cambrian to Oligo-Miocene age rocks. The Pre-Cambrian Pinal Schist occurs at the south portion of the property. The outer portions of the project are covered by Glory Hole and Galiuro Volcanics.
The center of the project covers a multiphase intrusive complex of Laramide age rock, consisting of the Copper Creek Granodiorite that has been intruded by a dark porphyry intrusion that measures 600 meters (“m”) by 400m. Outcropping within this dark porphyry intrusion is a cluster of breccia pipes, some of which exhibit interstitial fillings of chalcocite, with lesser bornite, chalcopyrite, pyrite and copper oxides. Gangue minerals in the breccia pipes include quartz, specular hematite, tourmaline, and adularia.
Thin dikes of “Gray Porphyry” have been intersected in several of the breccia pipes and is exposed in outcrop in the southern portion of the property. The Gray Porphyry is the unit most closely related to economic copper mineralization at the Copper Creek deposit and may be the source of the mineralizing fluids in the breccia pipes on the Sombrero Butte project.
At least 40 mineralized breccia pipes have been located on the property. In addition to the mineralized breccia pipes; 12 breccia pipes contain dickite, a mineral that forms under acidic, high temperature conditions. Dickite is an indicator mineral that occurs in multiple porphyry copper deposits throughout the Arizona copper belt including the San Manuel-Kalamazoo deposit.
Between 2006 and 2008 Bell Copper Corporation drill tested the mineralized breccia pipes located at the north end of the Sombrero Butte project. The drilling focussed on the Magna-Campstool-Rattler-Audacious-Sunset-Saguaro and Victors breccia pipes which occur within an area that measures 300m by 200m.
Previous Drilling Results:
Bell Copper completed 34 holes. Intervals of copper mineralization are listed below. Bell completed multi-element analysis on diamond drill holes (“DDH”) SB-01 to SB-23. DDH SB-24 to SG-34 were only analyzed for copper. The concentrations of molybdenum-gold-silver-arsenic-antimony-tungsten in the samples were not discussed by Bell Copper.
The mineralized intervals listed in the above table do not represent true widths. These results were previously announced by Bell Copper.
In 2012, Copper Fox acquired the Sombrero Butte property with an exploration target of a buried porphyry copper system based on the presence of the breccia pipes and the Copper Creek granodiorite.
Between 2013 and 2015, two surface exploration targets were identified that exhibited multiple mineralized breccia pipes, vein controlled copper-molybdenum mineralization, potassic-sericite alteration and sporadic tourmaline veining over a horizontal distance of 4 kilometre (“km”).
The first target measures 1,000m by 1,200m with copper values in outcrop ranging from 0.076% to greater than 0.25% and from 0.007% to 0.025% molybdenum. Eight of the mineralized breccia pipes located within this area were drilled by Bell Copper between 2006 and 2008.
The centre of the second exploration target coincides with a cluster of mineralized breccia pipes and Gray Porphyry dikes located about 2km southeast of the first target area. This target measures 1,600m by 2,800m. Mineralization in outcrop where sampled returned from 0.076% to 0.24% copper and from 0.007% to 0.049% molybdenum.
In 2015, Copper Fox completed a two line Titan-24 DCIP (“Titan”) survey over the exploration targets identified in 2013. The Titan survey outlined a positive chargeability/resistivity anomaly below the first and second target areas that ranges from 3,400m to 4,300m long, is at least 600m wide (open to the east and the west). The anomaly extends from surface to a depth of greater than 500m.
In the first target area, Line-2 of the Titan survey identified several chargeability anomalies between 200 and 400m below surface. Historical DDH’s located in proximity to Line-2 yielded the following results: The molybdenum-gold-silver concentration reported below were not previously reported.
- DDH SB-03 (Campstool breccia) intersected two intervals of copper mineralization in breccia (from 224 to 318m averaged 0.23% copper; from 466 to 492m averaged 1.19% copper, 0.013% molybdenum, 0.08 ppm gold and 4.83 ppm silver). The interval from 548 to 578m hosted in potassic altered granodiorite averaged 0.14%, 0.004% molybdenum, 0.015 ppm gold and 0.53 ppm silver. Fracture controlled chalcopyrite-bornite mineralization are reported from this interval.
- DDH SB-23 (Magna breccia) was drilled to a depth of 1,230.7m and intersected 0.77% copper from 276 to 358m and from 458 to 506m; 1.27% copper, 0.04% molybdenum, 0.085g/t gold and 3.81g/t silver in breccia. The interval in this DDH from 476 to 484m consisted of granodiorite boulders within the breccia and averaged 1.61% copper, 0.029% molybdenum, 0.056g/t gold and 5.90g/t silver. The interval from 700m to the end of the hole at 1,230m exhibited weak pyrite and chalcopyrite mineralization which suggests the outer pyrite shell of a porphyry copper system.
- DDH SB-11 (Rattler breccia) was drilled to a depth of 389m. This hole intersected 0.13% copper, 0.002% molybdenum and 0.05g/t gold in breccia over the interval from 282 to 304m. The interval from 312 to 342m averaged 0.37% copper and 0.007% molybdenum.
A compilation of the Titan survey (Line-2) and the drilling completed by Bell Copper shows that DDH SB-03, SB-23 and SB-11 tested a chargeability anomaly (L2IP5) that coincides with the mineralized breccia intersected in these holes. The Titan survey also shows positive, steeply dipping chargeability anomalies that correlate with the locations of other breccia pipes exposed on surface.
Chargeability anomaly (L2IP6) is located below and north of chargeability anomaly L2IP5. The top of this anomaly is at a depth of about 400m below surface and has not been drill tested. The chargeability signatures suggests that anomalies L2IP5 and L2IP6 are the same chargeability signature.
Five historical drill collars were located within Target #2, two of which are in proximity to Line-2 of the Titan survey. Analytical results for these holes are not available. The drill cuttings from these drill holes were sampled and yielded up to 0.23% copper. While this is considered positive, the grade and thickness of copper mineralization cannot be estimated.
In 2016, Copper Fox completed a study of the trace element geochemistry of the breccia pipes focussing on the chemical associations typical of a porphyry copper system (molybdenum-gold-silver-arsenic-stibnite-barium and manganese).
The study indicates the following technical points which support the presence of a buried porphyry copper system:
- Host rocks to the breccia pipes are a medium to coarse grain biotite-hornblende granodiorite and a medium grained, grey biotite granodiorite.
- Gray Porphyry (containing up to 0.48% copper and 0.035% molybdenum); a porphyritic intrusive (containing up to 0.13% copper) and non-mineralized andesite dikes intrude the breccia in the Magna pipe.
- Intervals in Magna pipe contain non-mineralized and mineralized granodiorite boulders. The interval from 476 to 484m averaged 1.61% Cu, 0.029% Mo, 0.056pppm Au, 5.9ppm Ag suggesting rafting of mineralized granodiorite from depth during breccia formation.
- The pipes are mainly clast (granodiorite) with minor amounts of matrix supported breccia.
- The breccia in the Magna-Campstool-Victors pipes contain i) significant copper mineralization and tourmaline as a gangue mineral, ii) a second mineralizing event introduced significant concentrations of molybdenum-gold-silver into the Campstool pipe (from 466 to 492m: 1.19% copper, 0.013% molybdenum, 0.08 g/t gold and 4.83 g/t silver) and Magna pipe (from 458 to 506m: 1.27% copper, 0.04% molybdenum, 0.09 g/t gold and 3.81 g/t silver), and iii) Gray Porphyry is the matrix in the lower portion of the Magna breccia.
- The copper mineralization in the Audacious-Rattler pipes is characterized by very high concentrations of Arsenic (to 10,368 ppm), Stibnite (to 260 ppm), Tungsten (to 128 ppm) and Manganese (6,270 ppm).
- The Saguero breccia pipe is not mineralized and contains very low concentrations of all elements. Tourmaline occurs in the matrix and as thin veinlets in the Glory Hole Volcanics surrounding this breccia.
The breccia study shows that three phases of copper mineralization (distinguished by chemical associations) has occurred within the breccia pipes. The three mineralizing events are described as follows: i) copper, ii) copper-arsenic-antimony-tungsten, iii) copper-molybdenum-gold-silver. The Magna and Campstool pipes contain significant concentrations of molybdenum-gold-silver (see table below) and are interpreted to be sourced from the same intrusive. This intrusive is interpreted to be represented by chargeability anomalies L2IP5 and L2IP6. The copper concentrations were reported by Bell Copper between 2006 and 2008.
The geochemical associations of the breccia pipes is interpreted to show an evolving porphyry copper system at depth that led to the formation of the breccia pipes. As the system evolved, based on the chemical associations and gangue minerals, the composition of the mineralizing fluids changed over time and were introduced into the different breccia pipes.
The chemical associations, intervals of copper-molybdenum-gold-silver mineralization, multiple phases of mineralization, correlation of the Titan results with the downward extension of the breccia pipes and tourmaline veinlets in the Glory Hole Volcanics supports the presence of a buried porphyry system on the property.