Summary:
The Aura project consists of the Wood Gulch-Gravel Creek area, the Doby George area, and the Maggie Summit. The PEA only covers the Doby George area.
Doby George is best characterized as a sediment hosted, pre-Eocene Carlin-type gold system.
Project Geology: Doby George Area
The rock units in the Doby George area include the Cambrian Prospect Mountain Quartzite and Edgemont Formations, Mississippian to Permian Schoonover sequence, Eocene Frost Creek tuff and a 150Ma Jurassic granodiorite intrusion known as the Columbia Pluton (Coats and McKee, 1972). The Blizzard Point, West Ridge, Daylight and Twilight mineralized areas comprise the Doby George gold deposits.
Deposit Form
The Doby George deposits comprise an outcropping, partially eroded, sedimentary rock-hosted Carlin-type system that has overall surface dimensions of 1700 x 800m. Drilling has penetrated gold mineralization from outcrop to depths of 700m.
West Ridge mineralization has surface dimensions of 700 x 350ms, locally attaining a thickness of up to 150m. Mineralization at the West Ridge deposit appears to have been controlled by a stratigraphic/structural zone following a north-south, 35°W trend that intersects with a N60°W-striking trend dipping 30° to the southwest. The N60°W trend extends at least 800m to the northwest into the Blizzard Point area.
The main Daylight area forms an "L" shaped zone with surface dimensions of 500 x 120m oriented N55°W. Mineralization is generally tabular in form, locally attaining widths of 50m following stratigraphy and low-angle structures dipping 20° to the southeast. High-angle mineralized structures extend N15°E from Twilight to Daylight, but the impact of these as controls of mineralization in the Daylight deposit is not clear.
The Twilight resource area has surface dimensions of 300 x 220m, locally attaining widths of 70m. The main Twilight mineralized zone appears to be more structurally controlled, forming where a steeply dipping northwest-trending structure intersects a set of northeast structures in favorable stratigraphy, forming subvertical bodies of breccia and stockwork.
The Blizzard Point mineralized zone has surface dimensions of 550 x 190m, ranging in width from 15 to 70m. Mineralization is tabular in form, trending N70°W and dipping 30° southwest. Mineralization is interpreted to follow favorable low-angle stratigraphy and/or structure. The main part of the modeled mineralized zone lies at the oxide/mixed interface beginning 60 to 90m below the surface.
Doby George Mineralization
Four zones of gold mineralization are recognized at Doby George: West Ridge, Daylight, Twilight and Blizzard Point. Pit constrained resources are present at West Ridge, Daylight and Twilight as of the Effective Date of this report. Scattered occurrences of gold mineralization occur in the Columbia Pluton granodiorite and in the Prospect Mountain Quartzite north and northwest of Doby George. The Tertiary volcanic rocks in the Doby George area are unmineralized.
Quartz introduced as veins, breccia, joint and fracture fillings, and silicification is the dominant type of mineralization observed in the Doby George sub-project areas. Gold is apparently associated with quartz irrespective of the content or goethite>hematite in the oxide zone. Gold grades in metallurgical core collected in 2022 showed a very low correlation with logged oxide intensity. The character of original sulfides has been obscured by oxidation, but petrographic analysis of Doby George core samples revealed the presence of pyrite, marcasite, arsenopyrite, sphalerite, chalcopyrite, galena, niccolite and gersdorffite.
The depth of oxidation averages 120 to 180m in the West Ridge deposit and 45 to 70m at Daylight and Twilight. The zone of mixed oxidation is highly variable, and ranges from 15 to > 100m based on drilling.
Deep Doby Zone
Three core holes and two RC drill holes drilled by WEX define a N15°W, 40° southwest-dipping zone of gold mineralization that has been identified around 620m to 670m below the surface. Currently the intercepts define an area about 120 x 80m, ranging from 8 to 30m in thickness.
Doby Deep mineralization is hosted in an intensely sheared package of interbedded, weakly calcareous, irregularly hornfelsed siltstones, fine-grained sandstones and greywacke, as well as mylonite composed of the same rock types. The zone is characterized by silicification, quartz veins, breccia, gouge and locally abundant remobilized carbon. Quartz veins are both high-angle cutting across shear fabric, and low-angle parallel to shear fabric. Qualitatively, gold is associated with silver, arsenic and antimony. Preliminary geologic interpretation by WEX in 3D models suggests the Deep Doby zone could be following a parallel but deeper mineralized zone under West Ridge, extending down-dip from North Doby or Daylight.
Columbia Pluton and Prospect Mountain Quartzite Mineralization
Local zones of gold mineralization have been identified in the Columbia Pluton on the north side of the Doby George area and in the. Cambrian Prospect Mountain Quartzite in the Columbia Basin northwest of Doby George.
In the granodiorite, gold is hosted in narrow fracture and fault zones several 10s of meters thick. Assay values from surface sampling of narrow quartz veins and vein breccias (hosted in sericite-clay altered granodiorite) ranged from 0.5 to 2.0g Au/t, with maximum values to 10.0g Au/t. Similar values were noted in legacy drilling, with the highest-grade assay of 7.5g Au/t in a 1.5m interval. Gold is associated with arsenic, silver and antimony. Mineralization is associated with quartz veins, quartz vein breccia and strong argillic alteration.
In the Prospect Mountain Quartzite, brecciated quartzite and associated quartz have returned gold values ranging from 0.5 to 2.0g Au/t. The quartzite typically contains finely disseminated pyrite. Gold in the quartzite is associated with arsenic. Remnant outcrops of silicified regolith, also geochemically anomalous, are present in the area of anomalous gold in Prospect Mountain Quartzite.