The Unga Project in Alaska hosts three primary epithermal vein systems at SH-1, Apollo Sitka, and Aquila. All three projects hold high grade gold and silver occurrences. All three showed promising drill results.
The property never had a modern, systematic exploration approach until now. Field exploration found six other unexplored targets, outside the three advanced locations.
Most of the exploration to date has focused on the Shumagin and Apollo-Sitka trends on Unga Island and the Centennial deposit on Popof Island. The rest of the prospects identified warrant further exploration. Priority targets include:
There are several additional exploration targets on the Midway Trend and Norm’s Trend. They will become higher priority targets in the near future.
Gold mineralization at the Centennial Zone is located on neighboring Popof Island within four kilometres of infrastructure and services at Sand Point.
“These excellent results demonstrate the high gold grades contained within the SH-1 zone at Unga. SH-1 is the most advanced target at Unga with 384,318 ounces of gold at 13.8g/t and is open to expand. Assays are pending for the remaining seven holes completed at SH-1 in 2020 and the resource is expected to grow. Unga received very little exploration in the last 40 years. However, it has several exciting, high-grade gold targets. Heliostar will continue to aggressively explore the property in 2021 with a goal of defining resources in excess of one million ounces.”
- Heliostar CEO, Charles Funk
SH-1 is a priority target at Unga. It holds a high-grade, inferred resource containing 384,318 ounces gold at a grade of 13.8 g/t and has significant potential for expansion, with high grade intercepts open along strike and at depth.
Historic work on Unga found a 43-101 compliant gold resource of 384,000 ounces at SH-1. The average grade at SH-1 is 13.8 grams per ton (g/t). It was a high priority target in the 2020 drill campaign. Drilling stretched over 1.75 kilometers.
Six holes drilled on the project in 2020 show the potential for the SH-1 Resource to grow:
The resource can increase both laterally and at depth. The four deepest intersections with the SH-1 vein hit gold more than 10 g/t with a few in excess of 100 g/t. The current resource estimate does not include the recent drill results.
The resource is centered on the Main Shoot, which is well defined by tightly spaced drilling, but is loosely defined by widely spaced drilling outside of this zone.
A 100-metre vertical gap existed between surface and the first historical vein intercepts and in 2020, seven holes were completed to improve our understanding of the rocks around the upper portions of the Main Shoot. The reported holes are 50 metre step outs on previously completed drilling. Based on previous drilling, it was possible to interpret both steep and shallow plunges to mineralization. Holes SH20-02 and SH20-03 suggest a steeper orientation is more likely and this will guide future drill hole placement and orientation.
The company also completed two deeper holes in 2020 to test depth extensions in areas of widely spaced drilling. These holes each intersected a wide vein, but gold mineralization is low grade. Epithermal veins have natural variability in the distribution of mineralization. These are just the first two holes out of 10-12 planned to systematically infill the loosely defined areas to better constrain the distribution of coarse-grained gold.
The deepest completed hole to date at SH-1 intersected 23.99 g/t gold over 5.48 metres in hole BM-01 and the company will continue to expand to depth where the system remains open.
Drilling along strike from the Main Shoot indicates parallel zones of mineralization that remain open and will be tested when drilling recommences in late March.
SH-1 is one of multiple epithermal gold targets along the 8.4km long Shumagin vein corridor. It is the most advanced prospect at Unga with a high-grade inferred resource and has considerable potential for expansion.
The SH-1 inferred resource sits at the eastern end of the Shumagin vein corridor, where quartz veining and alteration with associated gold mineralization form an elongate hill.
At SH-1, the vein occurs between rhyolite in the hanging wall to the southeast and andesite in the footwall to the northwest. The vein comprises a multi-episodic quartz vein, with a core of competent, brecciated quartz vein that grades outwards through an intense to weak zone of quartz alteration. The veins and strongly silicified zones carry the gold and silver mineralization. The mineralization is associated with the zinc and lead sulphides, sphalerite and galena.
“The Aquila target is delivering with these results defining another centre of mineralization at Unga. The phase one 2021 program has now defined shallow gold footprints over large areas at both Apollo and now Aquila, and assays remain pending for these and other targets at the project. The geological interpretation is that Aquilla is just the top of a mineralized zone and our next step is to undertake diamond drilling to define the full extent of mineralization at depth and along strike.”
- Heliostar VP of Exploration, Sam Anderson
Aquila sits six kilometers south of SH-1 on the same Shumigan Trend. Historical work in the 1980’s identified it as a zone of interest. Trenching found outcropping gold in epithermal veins. The best result was 11.48 g/t gold and 53.47 g/t silver over 3.66m.
Historical drilling at the site did not recover much of its core. The lack of results caused the project to sit idle until Heliostar’s team revisited it in 2020. They identified targets and drilled exploratory holes.
Heliostar’s first drill hole hit a wide, shallow zone of gold mineralization. That opened an entirely new area of exploration. Heliostar drilled five holes at Aquila. The table below summarizes the findings:
The early success at Aquila opens a new section of the historic Shumagin Trend. This is an early-stage project. Data shows that the Shumagin Trend is a conduit for gold-rich fluids. At Aquila, the broad, low-grade mineralization hints that there may be a newly identified feeder zone.
The Aquila Target comprises outcropping epithermal quartz veins within the Shumigan vein corridor located 5 kilometres southwest of the SH-1 Resource (384,000 inferred ounces of gold at 13.8 g/t gold). It is one of the four highest priority targets on the Unga project (Figure 1) amongst 38 areas of either mineralization, mineralized outcroppings, historical resources and/or anomalies.
In 2021, thirteen RC holes were completed at Aquila; all intersected the Amethyst Vein (Figure 2) which now has a drill defined minimum strike length of 475 metres. Two separate zones along the vein contain higher-grade gold mineralization and both remain open for expansion with follow-up diamond drilling.
Results from drill holes AQRC21-12 and 13 are step-out holes and were drilled 80 metres and 120 metres to the northeast of the discovery hole AQ20-01 (4.46 g/t gold over 3.6 m and 2.24 g/t gold over 17.37 m). In total, five holes define a zone of continuous mineralization that is at least 120 metres long and that remains undrilled and open to the northeast and at depth. Surface samples returned up to 30.8 g/t gold to the northeast that are yet to be drill tested.
Heliostar performed all 2021 drilling at Aquila with RC and the deepest drill intercept to date is only 70 metres below surface. Mineralization is open at depth with the expectation that there is a significant window for mineralization down-dip.
The company interprets that the current drilling as being at only at the top of the mineralized system. The geological evidence of a high gold to silver ratio, high precious metals to base metal ratio, relative elevation of Aquila to SH-1 and Apollo and specific quartz textures observed within the veins indicates a shallow level within the system. At Apollo, mineralization was defined over 500 metres vertically and drilling at SH-1 has defined high grade gold over 250 metres vertically that remains open at depth.
Heliostar’s geologists infer that the Aquila target has excellent potential for further expansion.
It is also important to note that gold mineralization becomes thicker to the northeast, around drill holes AQRC21-12 and 13, indicating that the gold mineralizing system may be becoming more robust in this direction. This area is a major intersection of the regionally significant northeast striking Shumagin Vein Corridor and several east-west striking veins. Vein intersections often form the basis for gold rich shoots within the veins which is looking likely in this zone at Aquila.
Table of significant intersections from Aquila:
“These are exceptional results and this discovery at Apollo adds another high-grade zone to the Unga project. Apollo was Alaska’s first underground gold mine. Despite historical reports of continuations of gold and base metal mineralization beyond historic workings, Heliostar is the first company to successfully intersect these veins in drilling. The Apollo-Sitka trend is over two kilometres long. To date, our field program expanded the strike extent to 745 metres with mineralized intercepts, a subsection of the broader two kilometre-long trend.”
- Heliostar CEO Charles Funk
The historic Apollo Mine produced approximately 130,000 ounces of gold at an estimated grade of 10 g/t. Ore is reported to have been mined from three closely spaced, parallel veins. The Apollo vein transitions from gold rich at shallow levels to gold with silver and base metals at depth.
Mining from 1886 through to the 1920s exploited the gold-rich, oxidized portion of the Apollo veins. However, unoxidized precious- and base-metal-rich zones were left unmined due to the lack of flotation technology to treat sulphide ore. That technology was developed later and has remained industry-standard for multiple decades.
Exploration during the life of the mine comprised shaft sinking, drifting, and cross cutting to discover veins at three main zones: Apollo Shaft 1, Apollo Shaft 2, and the Sitka Mine (Figure 6). Historic reports note that many drifts and crosscuts encountered veins with gold, silver, and base metals which were not followed up with drill testing.
The Apollo prospect remained largely unexplored until the 1980s. That’s when a previous operator drilled fourteen holes to test the area north of the historic underground workings. However, this drilling did not encounter the main zones of mineralization. The project saw no further drilling until Heliostar completed seven holes in late 2020.
Heliostar geologists noted inaccuracies in the historic mine drawings and locations of the 1980s drillholes in the field. Those discrepancies indicated that the holes had not adequately tested the main Apollo-Sitka vein corridor.
Four holes drilled in 2020 intersected a halo of low-grade mineralization around mined-out areas at Sitka Mine and intersected veins near the main mine at Apollo Shaft1. It remains unclear if this drilling intersected the main vein at Apollo Shaft 1 or additional parallel veins to the north.
In 2021, drilling continued at Apollo with a focus on the Shaft 2 and Sitka Mine shaft areas.
In 2021, Heliostar drilled fences of reverse circulation (RC) drillholes to accurately locate the vein, with exploration drilling then to step-out along strike to expand the lateral footprint of mineralization.
Hole APSRC21-01 intersected a broad zone of intense clay and pyrite alteration, indicating proximity to a major structure. Hole APSRC21-02 intersected the vein on the same section (Figure 9). APSRC21-03 drilled back and across the vein near to the APSRC21-02 intersection and drilled through same vein but returned a low-grade interval. This grade variability is similar to that noted in drilling at the SH-1 resource. This variability is assumed to be the result of coarse-grained gold and screen fire analysis is being completed on each hole to address this variability.
Step-out drilling intersected at least three parallel veins between Apollo Shaft 2 and the Sitka Mine. Veining is composed of quartz with minor clay and variable amounts of sphalerite, galena and chalcopyrite. Geologists observed visible gold in RC chips from the high-grade interval in hole APSRC21-02.
The team completed one diamond drillhole, APS21-08. The hole intersected the Apollo vein 40 meters downdip, where it remains open to depth and along strike.
At Shaft 2, multiple veins have been intersected with a main vein defined over 365 m of strike and 100m of depth. Mineralization varies from gold-dominant (APSRC21-02, APSRC21-06) to base metal-dominant (APSRC21-08) and appears to change rapidly over short intervals. Controls on mineralization are not yet well understood but intercepts remain open to depth and to the west.
At Sitka multiple sub-parallel veins also occur, though a main vein aligns with the shallow stope and with mineralization defined over 385m of strike and 100m of depth. Mineralization also varies from gold-dominant (SKRC21-10) to base metal-dominant (SKRC21-04 and SKRC21-05). In the far east of the Sitka target, a fault appears to offset mineralization between hole SKRC21-08 and SKRC21-10 (Figure 1). Mineralization remains open to depth and to the west.
Drilling intersected high-grade gold over a strike length of 745m at Apollo. Follow-up diamond drilling is a clear priority given the widespread nature of the intercepts and to test the along strike and deeper targets indicated by historic exploration shafts and tunnels.
Table of intersections from the Apollo prospect:
“Unga is a rare project containing the potential for multiple deposit types. These holes show the potential for a gold-copper porphyry at the Zachary Bay target. They represent first pass drilling to establish the best location for follow-up diamond drilling. Both holes have higher grade sub-zones. It is important to note that hole ZBRC21-02 has grades that increase with depth and the best intervals are at the very base of the hole. High grade gold is the company’s primary focus, however the proximity of the different deposit styles, as was the case at the Saddle and Saddle North deposits that GT Gold (now Newmont) discovered in northern British Columbia highlights the potential value creation of exploring both styles of mineralization.”
- Heliostar CEO Charles Funk
The Zachary Bay Porphyry is a compelling drill target based on several factors:
The overall size of the porphyry core (300 x 650 m) based on mapping and ground magnetics surveys;
A zoned alteration from (500 x 1,000 m) from outer propylitic, argillic and advanced argillic alteration in andesite to a core of potassically alterted porphyritic diorite;
Only a single 117 metre deep, vertical hole drilled within the porphyry prior to Heliostar. This hole was mineralized over its entire length;
The proximity to the potentially related, high grade vein corridors.
A joint Quintana Minerals Corp. and Duval Corp. exploration program identified Zachary Bay in 1974. One round of drilling was completed with 4 holes totalling 291 metres in 1975. Of these four holes, only one was drilled in the porphyry and the other holes were drilled at other targets located over 400 metres to the east of Zachary Bay.
The 1975 hole (Z1) was drilled vertically, a poor orientation to effectively test a large, sub-vertical porphyry complex, but nonetheless returned 0.45 g/t gold equivalent over 107.1 metres (0.28 g/t gold and 0.11 % copper), with individual gold values up to 0.95 g/t. Mineralization remains open in all directions (The reader is cautioned that the qualified person has not been able to independently verify the historical assay results in the Quintana Duval drilling).
Our primary focus at Unga is high grade gold targets. However, the project also hosts both porphyry gold-copper and bulk tonnage gold targets.
In 2021, Heliostar completed two first-pass RC holes targeted porphyry style mineralization at Zachary Bay. Both holes intersected gold and copper mineralization over significant widths. They indicate potential for a large porphyry footprint with zones of higher grade that require additional drilling.
Heliostar’s compilation of the historic drilling, magnetic surveying, and two IP survey lines from 2005, combined with detailed field mapping completed by Heliostar in early 2021 confirmed a large porphyry system at Zachary Bay, with large areas masked by thin (0-10 metres) overburden.
The team completed two RC holes to test the extent of the porphyry complex. Hole ZBRC21-01 was a 135 metre step towards the south from 1975 hole Z1. The entire hole returned 118.9 m of 0.39 g/t gold equivalent (0.15 g/t gold and 0.15% copper) from 9.14 m in a diorite porphyry covered by thin overburden. Within this zone intervals of higher grade include 16.76 m at 0.58 g/t gold equivalent, with individual assays up to 0.42 g/t gold and 0.3 % copper.
The presence of both higher grade zones of mineralization and variable gold-to-copper ratios suggest multiple porphyry and alteration phases. Testing the extension of these zones will be the focus of follow-up drilling.
Hole ZBRC21-02 is located at the edge of the northern magnetic high, 108 metres northeast of the historic hole Z1. The location is near a small outcrop containing magnetite and chalcopyrite veining hosted by diorite porphyry. The entire hole contained gold and copper mineralization from surface to the end of hole at a depth of 100.58 m. Grades for the interval average 0.34 g/t gold equivalent (0.19 g/t gold and 0.09 % copper).
However, most significant is that the mineralization increased towards the end the of the hole which terminated in 3.05 m of 0.64 g/t gold equivalent (0.41 g/t gold and 0.14% copper). The hole is drilling towards the most intense magnetic high within the Zachary Bay target but ended due to limitations of the RC drill rig before testing the magnetic target. This will be a clear target for follow-up drilling.
Table of significant intersections from the Zachary Bay target:
“We are excited about the new feeder zone potential at Centennial. This target is the low-hanging fruit at Unga. We know the gold is there, from the work done in the 1980’s. Our research shows potential for high-grade feeder zones. And we know that Unga is a rich system, with high-grade potential. We are excited to run the first aggressive exploration program at Centennial in over 30 years.”
- Vice President of Exploration Sam Anderson
The Centennial deposit sits about 2 miles south of the town of Sand Point on Popof Island. Exploration and drilling by Battle Mountain Gold Corp in the 1980s at the Centennial Zone revealed a gold zone 750m long by 400m wide in a flat-lying, outcropping dacite tuff containing fine, free-gold.
The Centennial target dates back to 1904, when Louis Hermin discovered placer gold on the beach at Popov Island. In the 1980’s Battle Mountain Gold out lined a small, shallow, low-grade deposit.
Over the past two years, Heliostar’s technical team performed a detailed review of historic data. In late 2021, the team ran a drone-supported reconnaissance-scale induced-polarization (IP) survey. The data identified a complex of vertical structures that could form feeder zones.
The technical team believes these could be the plumbing for the gold outlined in historic drilling. Testing these new targets convinced the Heliostar team that Centennial should be the priority target at Unga.
This mineral resource estimate was not prepared in accordance with National Instrument 43-101 nor in accordance with guidelines of the Canadian Institute of Mining and Metallurgy. Heliostar is not treating this resource estimate as current.
Analysis of the original Centennial drill results indicates that the sub-vertical dip of most of the drill holes outlined gold mineralization in the flat-lying tuff but may have missed sub-vertically inclined, gold-bearing feeder veins. The Centennial deposit provides an example of potential bulk-tonnage-style gold mineralization at the Unga project.
The team will focus on the higher-grade feeder structures within the broad, low-grade bulk-tonnage gold mineralization at Centennial. The current plan calls for one reverse circulation drill rig to test targets.
There is evidence that where the historical trenches crossed the vertical structures, they encountered higher grade material. Additionally, the vertical drilling often missed these structures entirely. A grade-thickness map, compiled by Battle Mountain Gold, hints at the potential for several high-grade feeder zones across the target area.
Future drilling at Centennial will advance another high-quality epithermal gold target at Unga. It aligns with Heliostar’s goal of developing one million ounces of gold in resources on the Unga Project.
After the placer discovery in 1904, miners developed several lode claims, but failed to find high-gold values. Poor exposure, thick brush, and intermittent gold inhibited subsequent exploration at the time. It remained unexplored until the 1980’s.
Battle Mountain Gold explored Centennial in the 1980s. The program included trenching and over 5,500 metres of core drilling. This historic drilling focused on low-grade bulk-tonnage style mineralization. It outlined a flat-lying, lithologically controlled mineralized body, roughly 1,200 meters by 600 meters in area.
The historic interpretation of the deposit was that gold-rich fluid hit permeable tuffs and spread laterally. Based on that hypothesis, only six of the 59 holes penetrated deeper than 250 meters.
Similar work on the nearby Propalof target found gold to a much lesser extent than at Centennial.
Previous workers described the mineralization at Centennial as hosted within a package of andesites and basalts with lesser volcaniclastic rocks. The rocks contain a dominant alteration assemblage of quartz, chlorite, sericite, epidote, potassium feldspar, pyrite, and carbonate. Previous workers noted an association of gold with silica and potassium, which may be adularia.
The IP survey suggested the presence of high-angle structures across the target area. Some of the features match the high-angle quartz veins exposed in the cliffs to the southwest of Centennial. However, the IP data indicates the structures have a dense, almost radial pattern. The structures intersect one another throughout the outlined gold mineralization at Centennial extending to the Propalof target
Heliostar’s data compilation and the drone magnetic survey strongly suggest that the high-angle structures could be the source of the gold-laden fluids. In addition, historic higher-grade drill and trench intersections near these structures support the potential higher-grade gold feeder structures.
High-angle quartz veins with historic workings can be observed in the cliffs immediately west of Centennial. The Heliostar technical team interpret these structures as examples of higher-grade feeder structures. Identifying similar structures will be the target of Heliostar’s drill program at Centennial and Propalof.
Composites table 20210325