HighGold Mining Inc. provide an update on its 2023 exploration and development program (the “Program“) including final drill results at the Johnson Tract polymetallic Gold Project (“Johnson Tract“, “JT” or the “Project“) in Southcentral Alaska, USA. The Project hosts the high-grade JT Deposit with an Indicated Resource of 1.05 Moz at 9.39 g/t gold equivalent (“AuEq“) with average true thickness of 40m.
Following completion of the spin-out of Onyx Gold Corp. this summer (see HighGold news release dated June 6, 2023), HighGold squarely focused on unlocking value at the high-grade JT Deposit. In parallel with exploration drilling to expand existing deposits and target new prospects, the Company launched on a major program of advanced exploration and de-risking activities to support the evaluation of a potential high-grade, low-impact, underground mine.
Highlights of the 2023 Program
- Initiation of preliminary scoping work to evaluate conceptual direct-shipping-ore (“DSO“) scenarios that offer the potential for a nearer term, lower capital cost and enhanced environmental benefit production scenario
- Completion of a comprehensive work program to support the permitting of an underground exploration ramp, including six (6) hydrogeology-geotechnical drill holes, related hydrogeology test work, engineering, and multiple environmental and cultural studies
- Infill drilling yields thick, high-grade mineralization typical of the JT Deposit in hole GT23-004
- 56.6 meters at 7.8 g/t AuEq, including
- 33.6 m at 12.1 g/t AuEq, and including
- 4.9 m at 34.9 g/t AuEq
- 56.6 meters at 7.8 g/t AuEq, including
- Narrow high-grade and broad low-grade mineralization intersected in 2023 step-outs at Ellis Zone
- 2.2 m at 57.0 g/t AuEq previously reported in hole DC23-070
- 1.4 m at 11.6 g/t AuEq in hole DC23-071
- 47.1 m at 0.7 g/t AuEq in hole DC23-087
- 64.1 m at 0.7 g/t AuEq in hole DC23-088
- Encouraging new zones of veining and JT-style alteration intersected in first pass drilling of new prospect areas, warranting additional follow-up in 2024
“We had a busy and productive field season this year,” said Darwin Green, President & CEO. “We completed a significant drill program aimed at expanding existing zones and targeting new discoveries. Results from the drill program are encouraging and will serve to inform ongoing drill planning and targeting as we continue to evaluate the multi-deposit potential of the Project. Infill hole GT23-004 is a reminder of the exceptional width and grade that characterizes the JT Deposit.”
“Thick, high-grade deposits in desirable jurisdictions with a path to relatively rapid and cost-efficient development are a rare prize in the mining sector. In conjunction with our drilling efforts, HighGold has also turned to assessing the development potential for the JT Deposit and demonstrating the intrinsic value of the Project. One such opportunity being evaluated is the potential development of a DSO mining operation, whereby mineralized material would be mined and transported via marine vessel to an existing mill off site. Another major step to advancing the Project is advancing the permitting and development of an underground exploration ramp. The Company is well capitalized to continue advancing these important value-added activities through 2024 and beyond.”
Direct Shipping Ore (DSO) Mining Studies
HighGold has begun preliminary scoping work to evaluate conceptual direct-shipping-ore (“DSO“) scenarios. This includes studies and investigations into potential mining methods, mine designs, and the logistics and infrastructure required for shipping mineralized material to an existing, off-site milling facility. The Project’s location near tidewater offers the potential for DSO via bulk marine transport (the lowest cost form of bulk shipping) either direct to Asia or to existing coastal mills at mines in Alaska and British Columbia.
Advantages of a DSO mine over a conventional mine include project simplicity, lower CAPEX and execution risk, and potential for an expedited timeline to production. A DSO mine at Johnson Tract would also have the attractive environmental benefits of a small surface footprint and minimal long-term management and closure concerns. Under such a scenario, development rock (waste-rock) would likely be integrated into the mining plan as backfill for permanent underground storage within the mine, and tailings would be stored at a pre-existing off-site facility, resulting in no on-site tailings.
DSO mining, although not common in North America, is used throughout the world as the margins and IRRs of a DSO Mine can be more attractive than in a conventional scenario. In Alaska, a DSO mining joint venture agreement is in place between Kinross Gold and Contango Ore, in which ore from the Mahn Choh deposit (proven and probable reserves of 998koz at 7.88 g/t gold) will be trucked 240 miles (380 km) for off-site processing at Kinross Gold’s Fort Knox mine.
2023 Advanced Exploration Activities
A key component of de-risking the Project is the development of an underground exploration ramp to the JT Deposit. The exploration ramp will provide a platform to conduct cost-effective tightly spaced definition drilling in the highest-grade portions of the known deposit to support future engineering and economic studies. The 1,800m long ramp, which is parallel to and slightly outboard of the trend of mineralization, will also provide access to efficiently test multiple deep exploration targets (Figure 1).
In support of this, the Company successfully completed a comprehensive field program from July to October 2023 consisting of hydrogeological test work, engineering, and numerous environmental and cultural studies. Over the coming months, the data from these studies will be incorporated into the project design and form the basis of the exploration ramp permitting that is planned to commence in early 2024.
In connection with the exploration ramp plan, a Section 404 permit application was submitted earlier this year to the US Army Corps of Engineers for a 2.6-mile (4 km) portal access road and expanded airstrip. This process is tracking well, with no significant deficiencies identified to date.
2023 Drilling Results
The final drill results from the 2023 drill program are reported herein. A total of 33 drill holes for 7,648 meters were completed, including 27 exploration holes (6,254m) and 6 geotechnical holes (1,394m). The exploration drilling targeted the main JT Deposit (2 holes) and the Ellis Zone (12 holes), as well as several new, previously undrilled prospects and targets at East DC Prospect (8 holes), Double Glacier (3 holes), and South Valley (2 holes). Locations of the new drillholes are presented in Figures 1 to 4, with key assay intersections displayed in Table 1 and described below.
JT Deposit (Geotechnical and Step-out Drilling)
The Company completed six (6) drill holes to carry out hydrogeological and geotechnical studies along the alignment of the proposed 1800m long underground exploration ramp, which is designed to be developed within unmineralized rock units in the hanging wall to the JT Deposit. One of the drill holes (GT23-004) was extended through the JT Deposit as an infill hole and to characterize ground and water conditions for future mine modeling. GT23-004 intersected typical JT-style Au-Cu-Zn mineralization and returned:
- 56.6 meters at 7.8 g/t AuEq (4.87 g/t Au, 0.61% Cu, 3.5% Zn), including
- 33.60 m at 12.1 g/t AuEq, (7.93 g/t Au, 0.9% Cu, 4.8% Zn), and including
- 4.90 m at 34.9 g/t AuEq (33.03 g/t Au, 1.2% Cu, 0.6% Zn).
- 33.60 m at 12.1 g/t AuEq, (7.93 g/t Au, 0.9% Cu, 4.8% Zn), and including
Separate from the geotechnical drilling, two (2) exploration holes stepped out 100 to 200 meters south of the JT Deposit for potential extensions along strike. These holes intersected broad zones of strong alteration with local silver-lead-zinc mineralization, including:
- 6.0 meters at 76 g/t Ag, 0.4% Pb, 1.2% Zn in drill hole JT23-153
Ellis Zone and DC Prospect Targets
The DC Prospect, located four kilometers northeast of the +1Moz AuEq JT Deposit, includes the high-grade Ellis Zone discovery and numerous other mineralized showings within a series of large gossan alteration zones extending over a 1.5 km x 3.0 km area. Drilling in 2023 included 50 to 100m step-outs on the Ellis Zone to sketch-in resource potential and first-time tests of new targets between the Ellis Zone and East DC Prospect areas.
Drilling in 2023 has now defined two distinct and overlapping styles of mineralization at the Ellis Zone; a steep-dipping, structurally-controlled high-grade quartz vein and sulphide breccia zone and a zone of shallow-dipping, broad, lower-grade potentially stratigraphically-controlled mineralization with VMS-style characteristics. The current interpretation is of a broad zone of stringer-style mineralization with local structurally controlled high-grade shoots. Mineralization has now been intersected over a length of 200 m and to a depth of 225 m.
Narrow high to bonanza-grade and broad low-grade mineralization have been intersected in 2023 step-out drilling at Ellis Zone, including:
- 2.2 m at 57.0 g/t AuEq (49.9 g/t Au, 25 g/t Ag, 1.5% Cu, 8.4% Zn) previously reported in hole DC23-070, including
- 1.1 m at 80.5 g/t AuEq, (71.4 g/t Au, 29.7 g/t Ag, 1.5% Cu, 11.7% Zn)
- 1.4 m at 11.6 g/t AuEq (4.51 g/t Au, 16 g/t Ag, 1.9% Cu, 1.1% Pb, 7.0% Zn) in hole DC23-071
- 47.1 m at 0.7 g/t AuEq (0.29 g/t Au, 0.5% Zn) in hole DC23-087
- 1.5 m at 163 g/t Ag and 4% Zn in hole DC23-088
- 64.1 m at 0.7 g/t AuEq (0.31 g/t Au, 0.7% Zn) in hole DC23-088, including
- 32.4 m at 1.0 g/t AuEq (0.53 g/t Au, 0.8% Zn)
Eight (8) reconnaissance drill holes were completed across a 1km east-west trend between the Ellis Zone and the East DC prospect area. The holes targeted mapped structures, alteration and mineralization as well as blind geophysical and geological targets that project beneath an area of landslide cover. Significant new zones of quartz-sulphide stockwork veining were intersected in five (5) holes at East DC with anomalous silver-copper geochemistry that warrant additional follow-up. Significant results include:
- 3.9 m at 97 g/t Ag in hole DC23-075
- 1.3 m at 2.7% Cu and 23 g/t Ag in hole DC23-076
- 1.2 m at 1.6% Cu in hole DC23-080
Other Regional Prospects – Double Glacier and South Valley
The Company also completed five (5) drillholes for initial testing of the South Valley and Double Glacier prospects 1.5 km and 3 km south of the JT Deposit, respectively. Though no major mineralized intervals were returned in the South Valley and Double Glacier drillholes, the Company did intersect the JT Deposit host dacite volcanic stratigraphy with weakly anomalous values of Au, Ag and Zn, and the same unique nodular anhydrite alteration assemblage which surrounds the JT Deposit. Of additional significance, drill hole DG23-003 retuned a 1.3 m at 2.3% Zn within a mudstone unit at the Double Glacier prospect, highlighting potential for VMS-style mineralization. Further work is planned to follow-up on these drillholes during the 2024 field season.
Table 1. Significant Assay Intersections from 2023 Drill Program at the Johnson Tract Project
|DC23-072||N Ellis Zone||166.5||168||1.5||0.01||0.9||0.03||0.01||2.62||1.6|
|DC23-073||N Ellis Zone||196.6||220.2||23.6||0.03||0.7||0.07||0.13||1.28||0.9|
|DC23-074||N Ellis Zone||No Significant Intersections|
|DC23-077||East DC||No Significant Intersections|