Significant Structure Identified at Pitfield

Empire Metals Limited / LON: EEE / Sector: Natural Resources

18 August 2022

Empire Metals Limited

Airborne Magnetic Survey Identifies Significant Structure at Pitfield Copper-Gold Project

Structure Closely Aligns with Previously Reported 7km Copper Anomaly

Empire Metals Limited (LON: EEE), the AIM-quoted resource exploration and development company, is pleased to announce the results of the airborne magnetic survey carried out in June 2022 at the Pitfield Copper-Gold Project ('Pitfield'), located in Western Australia.

Highlights

·    Close spaced (50m line spacing) airborne magnetic and radiometric survey completed over the previously reported magnetic anomaly extending from near the western boundary and through much of the 615 sq km Pitfield licence area.

·    A significant structure has been interpreted along the western boundary of the magnetic anomaly that closely aligns with a surface copper anomaly stretching over 7km, previously identified by CRA (which became part of Rio Tinto Group) when conducting surface sampling in the early 1990s.

·    Pitfield is located immediately adjacent to the historic Baxters copper mine at Arrino which produced 106 tonnes of copper ('Cu') at a grade between 20-30% Cu which, along with numerous other prospects, demonstrates high regional prospectivity for copper

·    The highly magnetic anomaly seen from the airborne survey, which extends for over 20km north-south along the western margin of the licence, indicates potential for the presence of magnetite which could be associated with a regional scale alteration event.

·    Excellent resolution of stratigraphy and structure has been achieved with the new survey which will greatly assist in understanding the geological location of known copper anomalism, and in targeting areas with the highest exploration potential during our field activities.

Shaun Bunn, Managing Director, said: "This is a tremendous result for Empire, and clear evidence of the mineralised potential of this geologically significant asset.  Our early success from the airborne magnetic survey has confirmed that the historical geochemical sampling closely aligns with a significant magnetic anomaly.

"We are very much looking forward to receiving the detailed analysis of our recently completed airborne electro-magnetic survey in the next few weeks, which was designed to complement this magnetic and radiometric survey work programme. These surveys, combined with the historical geochemical mapping completed by CRA and others, will allow our technical team to develop a comprehensive geological map and database for the Pitfield project, with the expectation that over time we can define several highly prospective copper resource targets."

The Pitfield Copper-Gold Project

Location and Regional Geology

Pitfield is comprised of a granted Exploration Licence (E70/5465) and an Exploration Licence Application (E70/5876) covering a total of 615 sq km. Pitfield is located near Three Springs, a town  313 kilometres north of Perth, Western Australia on the Midlands Road, which until the opening of the Brand Highway in 1975 was the main road route from Perth to the state's north. (refer Figure 1).

Figure 1.- Location Map - Showing Pitfield Tenements and Major Access Roads.

Local Geology and Historical Mining Activities

Pitfield lies at a unique setting along the boundary of Western Yilgarn province, where a major craton-scale structure internal to Southwest Gneiss province intersects and offsets the Yilgarn margin and controls the position of the Neoproterozoic Yandanooka basin, the only example of this globally important copper prospective age adjacent to the western Yilgarn craton.

Pitfield encompasses much of the highly prospective Neoproterozoic Yandanooka Group sediments consisting of sandstone, siltstone and polymictic conglomerate with andesite to trachyte clasts. A rib of the Mesoproterozoic Mullingarra Gneiss is exposed close to the western margin of the project area.

About 25% of the project area is exposed/weathered Proterozoic rocks of the Yandanooka Group where the known copper prospects are located. There is minor Permian cover and 70% of the area comprises a shallow transported cover. Previous government geophysical surveying showed a gravity-high anomaly which suggests higher density mafic rocks at depth, which may provide a source for copper within the project.

Major lithological contacts, either within basins or at the basement contact (particularly transitions between oxidised and reduced rocks) can focus copper deposition. Pitfield is located along strike from the historic Baxters copper mine at Arrino which produced 106 tonnes of copper at a grade between 20-30% Cu which, along with numerous other prospects, demonstrates that the copper mineralisation process has occurred in the Pitfield area.

Geochemical sampling by CRA and others has confirmed that a previously identified magnetic anomaly associated with alteration including magnetite/ hematite, epidote replacement and fractures and carbonate-quartz veinlets is host to extensive copper anomalism, extending south from Baxters and with greater than 150ppm Cu in soils identified over a strike length of 7km (refer Figure 2.).  The anomaly remains open to the south and east including over 10km of this high-intensity magnetic feature within the project which is yet to be explored. Limited exploration has been undertaken within the project outside a 5km radius from the Baxters mine.

CRA (1993) completed IP geophysics and auger sampling which defined a significant Cu-in-auger anomaly (plus Ag) over some 7km strike length open to the east and south and followed up with two diamond holes, the southern hole on Pitfield recording copper anomalism with a maximum value of 570ppm (from 4m chip samples of drill core) associated with fracture-controlled malachite and minor native copper. In addition, CRA surface sampling partially covered the Pitfield project with soils and stream sediment sampling which confirmed multiple areas of significant copper anomalism.

Results of Airborne Magnetic Survey

The previous governmental regional magnetic surveys were flown at 200m line-spacing and indicated strongly magnetic stratigraphy/alteration within the project area. Empire's more detailed survey, completed by Magspec Airborne Surveys Pty Ltd in June, was flown on a 50m line spacing at a height of some 30m and comprising some 3470 line km, giving an enhanced magnetic and radiometric resolution over the main areas of interest (Figure 3.)

This has provided valuable structural, stratigraphic and surficial cover details which, along with the airborne electromagnetic survey results soon to be received plus the compilation of the historical soil and rock chip sampling,  will greatly assist with prospect-scale target definition for geochemical mapping and future drilling campaigns.

Copper mineralisation has previously been mainly found within the non-magnetic sandstone and siltstone units which lie along the better exposed western margin of the Yandanooka sedimentary basin and the basement Mulingarra Gneiss. The highly magnetic anomaly seen from the airborne survey, which extends for over 20kms in a north-south dimension, is likely highlighting the Beaconfield conglomerate unit. Importantly, the Beaconfield conglomerate unit contains mafic to intermediate volcanic clasts, which are highly susceptible to the formation of the mineral magnetite during regional scale alteration events. During such events major lithological contacts, either within basins or at the basement contact (particularly transitions between oxidised and reduced rocks) can focus copper deposition. The western margin of the magnetic feature coincides with the mapped outcrop position of Beaconsfield conglomerate along a NNW-trendiong ridge, however the geological setting of much of the remainder of the magnetic anomaly is concealed under shallow cover and not yet fully understood.

The historic exploration by CRA, Kennecott, and Carpentaria Exploration (MIM), who concentrated their work on this contact south of the old Arrino (Baxters) workings, has comprised:

i.      a few bedrock diamond drill holes focussed on the Baxters mine area, plus very isolated stratigraphic holes; and

ii.     shallow Air Trac and RAB drilling where single samples (at variable depths down hole) where collected from the end of hole.

This work is shown on Figure 4 below and defines a strongly copper anomalous trend (>400ppm copper) along the interpreted structural corridor on the western margin of the magnetic high domain which extends for at least 7km and remains open to the south. Little additional drilling has been completed elsewhere within the project area.

Figure 4. Pitfield enhanced magnetic and gravity background in relation to CRA historical RAB drilling. 

CRA surface sampling comprising soils, auger and stream sediments are shown on Figure 5, and reinforces that the strongly copper anomalous trend seen in the shallow drilling does extend further south, but also highlights significant copper anomalism in other areas such as Mt Scratch. The main copper trend along the western margin of the magnetic feature coincides with a NNW-trending topographic ridge with residual soils and sporadic outcrop. In the eastern part of the CRA soil sampling area surficial cover encroaches and the soils response diminish commensurately, but Empire considers the soils to be less effective, and require an alternative exploration approach.

Figure 5. Pitfield enhanced magnetic and gravity background in relation to CRA historical soil and stream sampling.

Market Abuse Regulation (MAR) Disclosure

Certain information contained in this announcement would have been deemed inside information for the purposes of Article 7 of Regulation (EU) No 596/2014, as incorporated into UK law by the European Union (Withdrawal) Act 2018, until the release of this announcement.

**ENDS**

For further information please visit www.empiremetals.co.uk  or contact:

About Empire Metals Limited

Empire Metals is an AIM-listed (LON: EEE) exploration and resource development company with a project portfolio comprising gold interests in Australia and Austria.

The Company's strategy is to develop a pipeline of projects at different stages in the development curve. Its initial focus has been on the high-grade Eclipse and Gindalbie Gold Projects in Western Australia.  The Company expanded its exploration licence area in April 2022 from 9.5km2 to 1,728km2 with the acquisition of the Pitfield Copper-Gold Project and the Walton Copper-Gold Project in Western Australia, and the Stavely Copper-Gold Project in the Stavely Arc region of Victoria. 

Empire also holds a portfolio of three precious metals projects located an historically high-grade gold production region comprising the Rotgulden, Schonberg and Walchen prospects in central-southern Austria.

The Board continues to evaluate opportunities through which to realise the value of its wider portfolio and reviews further assets which meet the Company's investment criteria.