The Cole Porphyry system defines the northern extent of the 7.5 km long Hawilson Monzonite (‘HM’) Complex near the Triassic-Jurassic unconformity at Kirkham property. Porphyry style alteration and mineralization is exposed at surface encompassing are area of 1000m x 800m. Multiphase monzodiorite porphyry intrusions emplaced as NNE-trending (015º) linear dikes within the upper Stuhini siliciclastic rocks. The first drilling at the Cole target in 2018 intersected multiple cm-scale gold-bearing massive sulphide veins highlighted by 137 g/t Au over 0.6 meters, similar to the gold-bearing veins found at the Snip mine, which produced 1.1 million ounces of gold at an average grade of 27.5 g/t from 1991 to 1999. (MINFILE, 2015: Snip, 104B 250; BC Ministry of Energy and Mines).
Cole is a typical sub-alkalic porphyry system associated with a series of northerly trending monzodiorite and diorite dikes cut by late-stage barren mafic dikes. Field mapping and drill core logging indicated a zonal pattern of remnant potassic, proximal sericitic, intermediate sericite-chlorite and peripheral propylitic (chlorite-epidote-carbonate) alteration. The widespread gossans are characterized by pervasive hematite-jarosite-limonite and green copper oxide minerals. The historic surface rock samples with 0.2-0.9% Cu and soils with 300 to >600 ppm Cu and 100-500 ppb Au well correlate with the sericitic alteration and veins in porphyry and host rocks. The contact zones of monzodiorite and feldspar porphyry dikes commonly represents abundant quartz-carbonate-sulphide veins with gold-rich mineralization.
Structural Setting and Control of Mineralization
The northeast trending structural corridor, referred to as the “Adam fault system” is recognized as the main control of monzodiorite intrusions and gold-rich mineralization at Cole porphyry system. Mineralization tends to occur in both hanging and footwall of the Adam fault. The higher gold-grades between 4.0 to 137.0 g/t Au are commonly associated with quartz-carbonate-sulphide veins constrained along syn-mineral conjugate faults. The linear sub-vertical porphyry intrusions and dikes appear to have a northeast (~25o) strike. This tabular geometry at Cole reflects the characteristics of the outer shell (“Carapace”) of a porphyry system open both laterally and vertically.
The Etta epithermal veins occur immediately to the west of the Cole porphyry system near the Triassic-Jurassic, Red Line unconformity (Nelson and Kyba, 2014). These cm-scale tabular sheeted quartz veins with over 1.0 g/t Au are spatially related to the Cole porphyry system. The epithermal veins are hosted within the propylitic altered sedimentary rocks of the Hazelton Group, which highlight the outer shell of the Cole porphyry system to be tested at deeper levels.
The drilling assays at the Cliff porphyry system indicated multiple sub-parallel high-grade gold zones clustered along the Adam fault. The 2018 and 2019 drilling campaigns identified clusters of cm-scale massive sulphide veins in porphyry intrusions and host rocks, which appear similar to the gold-bearing veins found in the Snip gold mine. These mineralized veins exhibit a classic suite of elevated epithermal gold pathfinder elements such as As, Ag, Bi, Sb, Se, and Te, which suggest an outer shell (“Carapace”) of Cole porphyry system
2018 Drilling Highlights
- Massive sulphide veins carrying 18 g/t Au over 7.7m including 137 g/t Au over 0.6m
- Transition westward into epithermal sheeted veins. (MTS New Release – Nov 20, 2018).
- Multiple 4-9m-thick gold intercepts of 40 to 0.74 g/t AuEq. along Adam fault system.
- Vectors towards a deeper mineralized porphyry system open vertically and laterally.
2019 Drilling Highlights
- Building on 2018’s high-grade drill intercepts, Metallis geologists outlined a large 1×1 km porphyry system associated with NE trending faults and epithermal veins at Cole target
- Over 200 continuous rock-chip samples from 21 trenches returned several 2m intervals of 5 g/t to 1.25 g/t Au, which formed the basis of 2019 drilling program.
- High-grade gold intervals ranging from 34 g/t AuEq. to 2.85 g/t AuEq. in the 2019 drill holes confirmed the presence telescoping gold mineralization at Cole.
- Broad intercepts with up to 47 g/t AuEq. correlate with silicified monzodiorite dikes highlighting the strong potential of a substantial porphyry system at depth.
Cole is a structurally controlled porphyry system characterized by extensive sericitic alteration including remnant potassic and linear gold zones characterized by intense quartz stockwork, and pyrite + pyrrhotite ± chalcopyrite veins carrying 0.35 to 1.0 g/t Au. Mineralization ranging from 1.34 to 2.85 g/t AuEq. in the 2019 drill holes and 137 g/t Au in KH18-19 assayed from the 2018 program confirmed the presence of substantial gold zones overprinting the Cole porphyry system, which remain open in all directions. (MTS News Release Nov. 2018)
Results from the field mapping and drill data has provided significant information to reconstruct the anatomy of faults, porphyry intrusions and alteration patterns. These features commonly vector toward the core zones of the Cole porphyry system, which may have a vertical extent of approximately 1.5 kilometers. The drilling assays provided a much better understanding of the control of mineralization.
Metallis’ technical team is planning a strategic exploration and drilling program, supported by IP and ZTEM surveys, that will test the expansion of near surface epithermal gold mineralization whilst simultaneously targeting the deeper core zones of the Cole porphyry system.