Revere Gold Project – Update
Highlights
- Bulk sampling continues to reveal a high grade and well developed saddle reef system carrying gold from surface
- Geological interpretation confirms strong structural and mineralised system similarities to the world class Bendigo Gold Province of Victoria, which includes the legendary Fosterville Gold Mine
- Bulk sampling primary and secondary ore crushing commenced
- Gekko gold processing plant mobilisation scheduled for September 2024
- 5,500m exploration drilling to commence late August 2024
Everest Metals Corporation Ltd (ASX: EMC) (“EMC” or “the Company”)is pleased to provide an update on the bulk sampling program at the Revere Gold and Base Metal Project (“Revere”) in Western Australia, located just off the Great Northern Highway approximately 90km to the northeast of Meekatharra in the Murchison Region, 900km north of Perth.
“The current bulk sampling program continues to unlock our understanding of the geological mineralised system which demonstrates the existence of repeatable high grade gold reef systems and associated mineralisation. The system has a strong geological correlation to the high grade, nuggety Bendigo gold fields deposits of central Victoria. The initial sampling to date does not do justice to the potential of the Revere Gold Project as we have only targeted a small part of the 7km system. We will continue with our accelerated systematic methodical approach to exploration and JORC resource categorisation drilling and sampling program, whilst concurrently progressing our Mining Permitting processes.”
EMC’s Executive Chairman and CEO Mark Caruso commented:
GEOLOGICAL INTERPRETATION UPDATE
The Revere gold reef system is now identified as a significant saddle reef gold mineralisation system[1]. It consists of numerous stacked folded quartz and saddle reefs along an anticlinal axis. The quartz reefs are typically consistent along strike and are surrounded by a mineralised halo with a distinct arsenic geochemical signature.
Historical drilling at Revere have found gold in numerous holes as indicated by the red stars in figure 1 and the anomalous grades in yellow. Intersected grades were between 0.1 to 28g/t in the RC drill holes but went over 1,000g/t in larger samples (1,195g/t from 80kg taken in 2007[2]) and when two bulk samples of more than 200kg were taken (258kg and 293kg) in 2018 the grades of the same reefs produced 18g/t and 357g/t. These are undiluted grades from the mineralised quartz reefs[3].
Figure 1: Historical drilling and Exploration Target resource area at Revere Project
The high gold grades from the current blast holes for the bulk sampling were correlated with visual gold intersections during bulk sampling. H13-9 is an example of high-grade gold mineralisation, with 46.8 g/t Auover 2mfrom 3-5m[4]. This was exposed during bulk sampling as the southeastern dipping limb of a saddle reef (Figure 2).
Figure 2: Reef along strike and following plunge of anticlinal structure, high gold grade intersected by hole H13-9[5]
Also, blasthole H12-8 intersected 97.0 g/t Au over 1m from 8m, H13-8 intersected 38.7 g/t Au over 1m from 2m and H33-8 intersected 1m at 21.0 g/t Au from 3m. All these high grade intersections correlated with a well-developed quartz reef limb which follows the anticline axial plane plunge at 8-10° towards the southwest.
Mineralisation is therefore quartz vein hosted and appears to be concentrated along anticlinal fold crests with mineralisation continuing along the north and south dipping legs of the saddle reefs. Total width and depth of the gold distribution along the anticlinal axis and bedding planes are yet to be established.
The significance of the identified gold mineralisation system is highlighted by the following aspects:
- Surface Gold Mineralisation: The gold mineralisation extends from surface, minimising the need for pre-stripping.
- Free Milling Gold: The gold is free milling, eliminating the need for chemical leaching for gold extraction.
- Coarse Gold: The gold is coarse and can be easily liberated by crushing to +1mm.
- Oxidised Zone: The free gold is located in the oxidised zone (free of sulphates), extending at least 120 meters from the surface, and is expected to remain free milling.
- High Nugget Content: 92-98% of the gold is nuggety and coarse, allowing for recovery through a simple, low-cost gravity processing circuit.
- Extensive Structural Feature: Gold has been found along the well-developed Revere system, extending over 7 km in strike length and up to 300 meters wide. This suggests the potential for a large mineralisation system with multiple gold deposits. EMC holds the mineral rights for the identified target area.
Figure 3: Schematic cross section of Revere Reef with conceptual targets along anticline structure
A challenging aspect of the system, as previously reported, is the nuggety nature of the ore body. This results in gold being concentrated primarily in highly enriched structural trap sites (dilation areas) as visible nuggets and coarse gold. Consequently, gold grades in these dilation trap zones can easily exceed 1,000 g/t, while just a few meters away, the mineralisation may only be a low-grade halo (<0.1 g/t). Such nuggety gold systems are well-documented and have been mined globally. A notable example similar to Revere is the Bendigo Goldfield, historically the second-largest gold producer in Australia after the Golden Mile at Kalgoorlie, with a cumulative output of over 60 Moz of gold[6].
Figure 4: Gold from iron rich zone at Revere within the fold axis
Cautionary Statement:
In relation to the disclosure of visual mineralisation of gold included in this release, including photos and commentary for geological context, the Company cautions that visual estimates of mineral abundance should never be considered a proxy or substitute for laboratory analysis where concentrations or grades are the factor of principal economic interest. Visual estimates also potentially provide no information regarding impurities or deleterious physical properties relevant to valuations.
Bulk sampling results supported by laboratory assay analysis are expected to be available in September 2024.
Bendigo Gold Field Geological Similarities
The Revere system shares many geological and mineralisation characteristics with the deposits of the Bendigo goldfield, including the Fosterville gold mine[7]&[8], specifically:
- Fault controlled deposits developed along and adjacent to sub-parallel mineralised deep and steep structures that provided pathways for mineralised fluids.
- Large intrusive granite pluton <10km away providing heat source for hydrothermal enrichment.
- Gold is coarse (0.1-2mm or large nuggets).
- Host rock has undergone low metamorphic grade (sub-greenschist).
- Strong geological continuity in the structure hosting the gold mineralisation – hundreds of meters.
- Grade continuity is generally low and irregular inside the host structure as gold is hosted in discrete high grade ore shoots and dilation trap sites over a few meters within the continuous host structure.
- High grade zones are restricted to localised quartz vein developments (ore shoots).
- Host rock is turbidites of siltstone, shales and sandstone – metasedimentary.
- More than one periods of gold mineralisation has enriched the ore body.
- Gold is quartz-carbonate vein hosted free gold to arsenopyrite-pyrite hosted gold.
- Chevron and open to closed folds with refracted fanning cleavage in fold hinges.
- Anticlinal fold with plunging axes. The structures closely follow the strike of bedding. Mineralisation is predominantly along anticlinal axial planes.
- Early phase ductile deformation laminated quartz veins are generally poorly mineralised as they pre-date the gold mineralisation event.
- Gold occurs predominantly in close proximity to laminated veinlets or bucky quartz-carbonate veins that are concordant to bedding. The gold is there for exclusively associated as follows:
- As free gold in quartz
- In association with sulphides in quartz
- In wall rock fragments in quartz
- In wall rock adjacent to quartz with sulphides
The mineralised reefs are surrounded by a broad halo of hydrothermal alteration comprising sericite, chlorite, carbonate and disseminated pyrite.
The scale potential of the above systems is attractive as it has historically produced, on average, 130,000 ounces of gold per each strike linear kilometre along the anticline axial surface stacked saddle reefs[9].
Figure 5: Stockwork of bucky reef with strong halo alteration
Bulk sampling has revealed and confirmed that the Revere System features a well-developed saddle reef structure along the anticlinal axis. This type of formation is highly favourable for hosting significant gold deposits similar to those found in the Bendigo goldfields[10].
The total widths (cross-sectional area) of the numerous reefs are not yet determined but have been exposed over a 20-meter-wide zone. It is believed that individual reefs may taper off along the dip of the fold limbs to the southeast and northwest. The reefs’ long dimension, running parallel to the anticline crest, extends for at least 100 meters along the dip of the anticline. The average thickness of individual stacked reefs appears to be 10-20 cm, with a vertical separation of approximately 2-3 meters between each reef.
In some areas near the anticlinal axial plane, vertical spur veins have developed in or along the slaty cleavage. These veins appear to be parallel to the fold’s axial surface, and close to or within the fold hinge (Figure 6). The presence of highly enriched visible gold in fold hinges and dilation zones on parasitic fold limbs indicates a well-developed, large hydrothermal gold system. The mineralised reefs have a similar high grades. A significant advantage of the Revere system, even compared to the Bendigo goldfield, is that the gold is oxidised to a certain depth (so non-refractory), free milling, and mineralised from surface. Additionally, the host material appears to be easily excavated once the lateritic cap (1-4 meters) is blasted.
Figure 5-2: Rhombic quartz texture from replacement of calcite carbonate on fault contact (left), Cross cutting spur veinlets in fold axis following cleavage (right)
BULK SAMPLE PROGRAM
The crushing contractor has mobilised to site and crushing and screening operations have begun, utilising mobile jaw and cone crushers. The mineralised material is being crushed to a size of less than 5mm and will be stockpiled before being processed using the Gekko plant.
Figure 6: Crushing high grade mineralised material
Due to specialised electrical part sourcing and weather issues, mobilisation of the Gekko Processing Plant has been rescheduled to September 2024 to commence processing the high-grade gold ore.
EXPLORATION TARGET
The maiden Exploration Target of 2.5 – 4.1 million tonnes grading at 1 – 2.5g/t of gold was reported in October 2023[11]. The current Exploration Target is based on historical drilling data over an area of ~800m long and ~150m wide (Figure 1). The saddle reefs or fault reefs appear to be at least 20-50m wide and are found to repeat or occur at least 7 times from surface to a currently defined depth of at least 130m. This information is based on 194 RC holes drilled in 2018 by Mineral Commodities Ltd (ASX: MRC) for a total of 8,845m and 1997 samples analysed for gold[12] . This target resource can have a potential grade of ~2.5g/t Au based on a determined average mineralised grade of 2.5g/t Au Bottle Roll Cyanide analysis from 80kg of drill sample material (DRC047:33-37m). The mineralised zones can therefore host a potential resource up to 334,000 ounces of gold (4.1 million tonnes of quartz lodes at SG of 2.5).
Cautionary Statement:
The potential quantity and grade of the Exploration Target is conceptual in nature and as such there has been insufficient exploration drilling conducted to estimate a Mineral Resource. There is a low level of geological confidence associated with the Exploration Target grade due to the nuggety nature of the resource. There is currently no certainty that further bulk sampling and exploration will result in the determination of an inferred mineral resource. The Exploration Target has been prepared in accordance with the JORC Code (2012).
The current Exploration Target grade will be determined by the results of a very large bulk sample programme of 36,000 tonnes. Trenching over these areas have already confirmed the presence of saddle reefs that will now be excavated and processed on site to determine the final recovery grade of the material. The bulk sampling grades will be applied to the known mineralised quartz reefs (known geological continuity) to determine an inferred JORC compliant resource as is the accepted method and industry standard for nuggety gold deposits.
Figure 7: Location map of the Revere Gold and Base Metal Project tenements in northeast Meekatharra; pending mining tenement highlighted in black
NEXT STEPS
- Continuation of 36,000 tonne bulk sampling program
- Continued Ore crushing and screening until September 2024
- Mobilisation of Gekko Processing Plant in September 2024
- 5,500m aircore drilling planned to commence in late August 2024
[1] ASX:EMC announcement; Bulk Sampling Reveals high Grade Gold Mineralisation At Revere, dated 27 June 2024
[2] ASX: ENT announcement; Annual Report 30 June 2007
[3] ASX: MRC announcement, High Grade Gold Mineralisation Results from Doolgunna Project , dated 5 September 2018
[4] ASX:EMC announcement; High Grade Gold Results From Drilling At Revere Gold & Base Metal Project, dated 21 May 2024
[5] ASX:EMC announcement; High Grade Gold Results From Drilling At Revere Gold & Base Metal Project, dated 21 May 2024
[6] Woodall R. (1990) ‘Gold in Australia’, in Geology of the Mineral Deposits of Australia and Papua New Guinea, ed. F. E. Hughes, Australasian Institute of Mining and Metallurgy (Monograph 14), Melbourne.
[7] G. Neil Phillips. And Martin J. Hughes (1996), The geology and gold deposits of the Victorian gold province, Ore Geology Reviews, Volume 11.
[8] Updated NI 43-101 Technical Report (2019), Fosterville Gold Mine, Kirkland Lake Gold.
[9] S. C. Dominy, I. M. Platten and M. D. Raine (2003) Grade and geological continuity in high-nugget effect gold–quartz reefs: implications for resource estimation and reporting, Applied Earth Science Transactions of the Institutions of Mining and Metallurgy, Volume 112
[10] Johansen, G.F., Raine, M.D., Dominy, S. C., Bartlett, J. K., 2003, Challenges of sampling extreme nugget-effect gold-quartz reefs at the New Bendigo Project, Central Victoria, Australia
[11] ASX:EMC announcement; EMC To Commence Bulk Sampling Processing Of High Grade Revere Gold Reef For JORC Resource Definition, dated 5 October 2023.
[12] Annual Mineral Exploration Report (A120658), 2019
