The Red Bluff group was originally staked in 1911 to cover an immense red bluff which comprises about 245 metres of cliff exposure along the south side of Bronson Creek. Between 1916 and 1920, two adits were driven, as well as several open cuts, which exposed good prospects in gold and copper. In 1919, a vein was reported along this side-hill and assayed values of copper, silver and gold across about 9 metres (Minister of Mines, Annual Report, 1919, page 84).
Three stratigraphic assemblages have been mapped in the region: (1) Upper Palaeozoic sediments and volcanics of the Stikine Assemblage, (2) clastic sediments of the Triassic Stuhini Group, and (3) Lower Jurassic sediments and volcanics of the Hazelton Group.
Four plutonic suites intrude the above: (1) Late Triassic calc-alkaline intrusions coeval with Stuhini Group stratigraphy, (2) Jurassic Copper Mountain, (3) Jurassic Texas Creek and (4) Tertiary Coast Plutonic suite. Metallogenically, Texas Creek potassium feldspar megacrystic porphyries are of primary interest as they are spatially associated with several gold deposits and showings in the area.
The five Crown-granted claims are underlain by Upper Triassic rock of the Stuhini Group which consists primarily of interbedded mudstone, siltstone and greywacke. These rocks contain clasts of both sedimentary and volcanic origin. Carbonate lenses are present as well as calcareous units within the section. The stratified rocks are intruded by intermediate to felsic stocks and plutons of Jurassic age and older that are related to the Texas Creek pluton suite and are known as the Iskut River or Bronson stock.
The mineralization occurs within an altered porphyry intrusion with a volcaniclastic sequence which is pyritized and bleached by carbonatization and silicification (refer to Stonehouse - 104B 107 and Snip 104B 250). These schists are chloritized and are extremely oxidized.
The stock has been pervasively altered by quartz, K-feldspar and magnetite which in turn is cut by quartz magnetite veins and stringers. Gold, copper mineralization predominantly occurs on the south contact of the intrusive and a hornfels siltstone. Quartz, chalcopyrite stringers and in some cases veins cut both the quartz magnetite alteration and quartz magnetite stringers. A large portion of gold, copper values are associated with this stringer stockwork ore.
There are several gold showings located on both the Red Bluff and Red Bird Crown Grants. Included on these claims is a copper-gold porphyritic intrusion located only a few hundred metres northeast of the Snip Twin zone (104B 250). Several showings grade between 3.43 to 30.86 grams per tonne gold. A fault zone cutting the porphyry with a 200 metre strike length hosts values from 3.43 to 8.57 grams per tonne gold across 0.3 to 0.8 metre with this zone. A 5 metre section of poorly exposed pyritic intrusion carries 8.57 to 20.57 grams per tonne gold across a 1.0 metre exposure at an elevation of 513 metres. At 290 metres elevation, a gossanous vein within mineralized porphyry grades 27.43 grams per tonne gold across 0.3 metres exposed thickness and 3 metres of exposed strike length (Skyline Explorations Ltd., Press Release, June 15, 1988).
Drilling in 1988, within the northern corner of the Red Bird Crown Grant (Lot 2859) returned good values of gold. A 15 metre intersection in drill hole RB 8 assayed 64.0 grams per tonne gold. Another 0.9 metre intersection from drill hole RB 8 assayed 8.26 grams per tonne gold (Skyline Explorations Ltd., Press Release, August 4, 1988).
In late 1993, International Skyline Gold Corporation calculated a mineral inventory of 100 million tonnes grading 0.65 gram per tonne gold, 0.14 per cent copper, 3.4 grams per tonne silver and 0.01 per cent molybdenum. A drill-indicated probable and possible mineral resource of 20 million tonnes grading 0.25 per cent copper, 0.71 gram per tonne gold and 2.65 grams per tonne silver is contained within the larger resource (Information Circular 1994-19, page 21).
In August 1995, the company estimated a drill indicated and inferred inventory of 90 million tonnes grading 0.16 per cent copper, 0.75 gram per tonne gold and 4.17 grams per tonne silver, plus the potential for recovery of molybdenum and iron from magnetite. A higher-grade potential open pit starter resource of 17 million tonnes grading 0.23 per cent copper, 0.72 gram per tonne gold and 3.10 grams per tonne silver is indicated within this inventory.
In 1995, with Explore B.C. Program support, International Skyline Gold Corporation carried out a 7-hole diamond drilling program totalling 2428.6 metres. This program and a review of all previous work allowed the company to refine its resource estimation to an inferred resource of 90 million tonnes grading 0.749 gram per tonne gold, 0.159 per cent copper, 4.17 grams per tonne silver and 0.005 per cent molybdenum. The project was advanced to the mine development stage and an Approval Certificate Application made as the first step in the Environmental Assessment Review (Explore B.C. Program 95/96 - M67).
International Skyline increased its resource tonnage in 1996 as a result of a further 2000 metres of diamond drilling. The company estimates a total resource of 97,920,000 tonnes grading 0.2 per cent copper, 0.576 gram per tonne gold and 2.65 grams per tonne silver (Information Circular 1997-1, page 18). The company has begun a series of studies leading to a feasibility stage, based on a 12,000 tonne per day milling operation.
Based on 14,800 metres of drilling in 77 holes, International Skyline Gold Corporation estimates a resource of 76,000,000 tonnes grading 0.162 per cent copper, 0.44 gram per tonne gold, 2.747 grams per tonne silver and 0.007 per cent molybdenum for the Bronson Slope deposit. The company plans mining in three stages over 14 years, beginning with a low strip ratio, high-grade starter pit with an estimated reserve of 22 million tonnes grading 0.207 per cent copper, 0.504 grams per tonne gold, 2.953 grams per tonne silver and 0.005 per cent molybdenum. The mill is planned to produce a gold and silver-rich copper concentrate and a separate molybdenum concentrate. The plant is also designed to recover a high-quality magnetite concentrate. Metallurigical testing has indicated good recoveries for copper, gold and silver, tests have also demonstrated that molybdenum and magnetite are recoverable. During 1997 the company continued with the preparation of a feasibility study and its environmental assessment project report. The project, as currently proposed, is a 15,000-tonne-per-day milling operation; capital costs were estimated at $150 million (Information Circular 1998-1, page 19).
Drilling in the high wall area, south of the deposit, intersected a zone of disseminated pyrite in hornfels that averages 0.58 gram per tonne gold across 70 metres (Exploration in BC 1997, page 15).
In December 1998, International Skyline Gold and Homestake Canada agreed to explore and possibly mine a portion of Skyline's claims neighbouring the Snip gold mine (104B 250). Skyline conducted underground drilling (1495 metres, 17 holes) and drifting (197.7 metres) on to its High 1, 2 and 3 claim group from the nearby Snip mine workings. Homestake will perform the mining and drilling that will be funded and directed by Skyline. Net operating profit from ore mined from Skyline's ground will be shared, 55 per cent Skyline and 45 per cent Homestake.
The High claims target area is interpreted to represent the strike extension of the Snip deposit on to Skyline's Bronson Slope property.
Exploration will focus on intersecting a previous drill intercept, which cut 15.77 grams gold per tonne across a 2-metre interval. The mineralization is adjacent to a quartz-calcite-sulphide stringer zone containing 4.9 grams gold across 1.6 metres. The intercept occurred 195 metres from the eastern end of the Snip mine and 75 metres inside the Skyline claim boundary.
About 400 metres up-dip of this target area, Skyline has traced a near-surface structure of disseminated and stockwork gold mineralization known as the Highwall zone. The zone can be followed along strike for about 800 metres on Skyline's property. The zone likely represents the easterly continuation of the deeper, high-grade structure being mined at the Snip deposit.
Based on a pre-feasibility study, International Skyline identified a resource of 79 million tonnes, grading 0.17 per cent copper, 0.006 per cent molybdenum, 0.48 grams per tonne gold and 2.70 grams per tonne silver (Information Circular 1999-1, page 8).
Royal Gold Inc. financed exploration on the property in 1999. Assays from the exploration drilling did not warrant further work by International Skyline Gold.
In 2008 Skyline Gold released a NI 43-101 compliant report containing updated resource estimates. Combined Measured and Indicated resources were 225.1 million tonnes grading 0.36 gram per tonne Au, 2.22 grams per tonne Ag, 0.14 per cent Cu, and 0.0077 per cent Mo. Inferred resources were 91.6 million tonnes grading 0.27 gram per tonne Au, 1.76 grams per tonne Ag, 0.13 per cent Cu, and 0.0080 per cent Mo (Technical Report for Skyline Gold Corporation, April 30, 2009, www.sedar.com).
In 2010 Skyline Gold released a NI 43-101 compliant report containing updated magnetite resource estimates. Combined Measured and Indicated resources were 163,160,000 tonnes grading 7.28 per cent Ma. Inferred resources were 6,300,000 tonnes grading 6.92 per cent Ma, calculated using a cut-off grade of 2.00 per cent Ma (Technical Report dated January 28, 2010, www.sedar.com March 5, 2010).
The 2020 drilling program conducted by Seabridge Gold Inc. found indications of higher-grade copper mineralization (0.62 per cent copper over 31.8 metres) and many of the earmarks of a large porphyry system which may lie below the drilling completed to date. The 2020 program was designed to test geophysical anomalies below the quartz rise lithocap that is host to a diatreme pipe containing gold-copper mineralized vein fragments. A total of 8,961 metres of core drilling were completed in 11 holes. Results were consistent with the alteration halo from a large porphyry system. Mineralized intervals of up to 158 metres grading 0.16 gram per tonne gold and 0.16 per cent copper were intersected, indicating that drilling to date is in the outer portions of a gold-copper porphyry (Press Release Seabridge Gold Inc. November 11, 2020).
Refer to Johnny Mountain (Stonehouse) (104B 107) for related details and common property work history.
