HIGHLIGHTS
- Exploration Target demonstrates potential for globally significant copper endowment at Tannenberg Copper Project, Germany.
- Exploration Target captures hanging wall and footwall mineralisation above and below the Kupferschiefer shale: a modern view of the deposit that the 1940 historical estimate did not contemplate.
- Validated by Kupferschiefer mining in Poland, where up to 95% of mineable copper at KGHM Polska Miedź S.A's operations is hosted in the same footwall sandstone and hanging wall limestone units that host the Tannenberg Exploration Target.
- Built on validated historical foundations: Exploration Target builds on the 1940 National Socialist historical estimate area; the 1984 St Joe historical estimate; validation via resampling and logging of 1980’s core by GreenX and digitised archive material collected since August 2024.
- An inflection point for the Project: With the Exploration Target estimated, GreenX now transitions from archive synthesis to active exploration, including accessing historical underground mines for Scoping Study-level metallurgical test work, seismic survey evaluation and commencement of an initial drill program.
28 May 2026 - GreenX Metals Limited (ASX:GRX, LSE:GRX, GPW:GRX, Germany-FSE:A3C9JR) (GreenX or the Company) is pleased to announce an Exploration Target at the Tannenberg Copper Project (Tannenberg or the Project), in Germany. The estimated range of potential mineralisation in the Exploration Target is: 144 – 279 Mt at 0.9% – 1.4% Cu and 15 – 21 g/t Ag for 1.3 – 3.9 Mt Cu and 69 – 188 Moz Ag.
Cautionary Statement: The Exploration Target has been reported in accordance with the 2012 edition of the JORC Code (JORC Code). The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource for the reported target areas. It is uncertain if further exploration will result in the estimation of a Mineral Resource.
Table 1: Exploration Target for Tannenberg | |||||
Prospect | Tonnes Range | Cu Grade Range | Ag Grade Range | Contained Cu Range | Contained Ag Range |
Zone 1 | 8 to 16 Mt | 0.9 to 1.4% Cu | 15 to 21 g/t Ag | 0.1 to 0.2 Mt Cu | 3.9 to 10.8 Moz Ag |
Zone 2 | 40 to 78 Mt | 0.4 to 1.1 Mt Cu | 19.3 to 52.7 Moz Ag | ||
Zone 3 | 96 to 186 Mt | 0.9 to 2.6 Mt Cu | 46.3 to 125.6 Moz Ag | ||
Total | 144 to 279 Mt | 1.3 to 3.9 Mt Cu | 69.4 to 188.4 Moz Ag | ||
GreenX’s Chief Executive Officer, Mr Ben Stoikovich, commented: “Today’s Exploration Target at Tannenberg is a result of 18 months of archive data search and synthesis. It also marks an inflection point where we transition from searching for archive data to ramping up our own exploration programs. The modern understanding of the Kupferschiefer system, demonstrated by the scale of Kupferschiefer mining operations in Poland today, shows that economic copper mineralisation extends well beyond the thin shale horizon that historical German exploration focused on. The size of the potential copper endowment at Tannenberg in Hessen, Germany, in the same geological formation of the world-class Polish deposits, justifies continued investment and exploration”.
Figure 1: Outline of the Exploration target and its relationship to previous historical estimates and historical underground mining operations at Tannenberg. Section A-B is shown in Figure 4.
EXPLORATION TARGET
The Exploration Target provides a modern view of the copper potential at Tannenberg. Unlike the 1940 Historical Estimate, which assessed only the thin Kupferschiefer shale horizon (refer to announcement dated 20 October 2025), the Exploration Target captures mineralisation in the hanging wall above and footwall below the shale. This is consistent with the modern understanding of Kupferschiefer deposits as evidenced at KGHM Polska Miedź S.A's (KGHM) mining operations in Poland. The sections below set out the historical foundations, the modern thickness model and the supporting work that underpin the Exploration Target.
Cautionary Statement: The Exploration Target has been reported in accordance with the JORC Code. The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource for the reported target areas. It is uncertain if further exploration will result in the estimation of a Mineral Resource.
Figure 2: Top-down view of the Exploration Target wireframe at Tannenberg.
From historical mining district to Exploration Target
The Tannenberg Project has a long-documented history of drilling, mining, and estimation work, providing well-defined and historically validated copper-silver mineralisation that underpins today's Exploration Target.
A 95-hole drilling campaign was completed by the National Socialist Government between 1935 and 1938 across the Richelsdorf Mining District. This dataset formed the geological basis for the construction of three Kupferschiefer copper mines within the Tannenberg licence area, Reichenberg, Wolfsberg and Schnepfenbusch. These mines operated between the late 1930’s and in some cases up to the mid 1950’s. GreenX has digitised and integrated this drillhole database into its geological models (refer to announcement dated 11 September 2025).
The 1940 historical estimate, produced by Mansfeldsche Kupferschieferbergbau AG (Mansfeld AG), is based on a spatially relevant subset of 18 holes from the 95-hole database and established 728,000 tonnes of contained copper* at an average grade of 2.6% copper (in the narrow Kupferschiefer shale only) between the Wolfsberg and Schnepfenbusch mines in the north and the Ronshausen area in the south (see Figure 1). The historical estimate covers mineralisation from a depth of 100 m in the north to 400 m in the southern end area near Ronshausen (refer to announcement dated 20 October 2025).
A later historical estimate from 1984 was produced by St Joe Explorations GmbH (St Joe), based on limited drilling between 1980 and 1984 (refer to announcements dated 2 August 2024 and 28 April 2025). The St Joe historical work estimated (20 October 2025) 169,000 tonnes of contained copper and 6.5 million ounces of contained silver within the small section of zone 3. St Joe assayed wider intersections and found that the mineralisation was up to 3.45 m thick. This is considerably thicker than the narrow Kupferschiefer shale assayed and estimated by Mansfeld AG in 1940. St Joe provided the first modern indication that economic mineralisation extends beyond the Kupferschiefer shale itself.
Cautionary statement for historical estimates: The historical estimates referenced in this announcement are not reported in accordance with the JORC Code. A competent person has not done sufficient work to classify the historical estimates as a mineral resource or ore reserve in accordance with the JORC Code. It is uncertain that following evaluation and/or further exploration work that the historical estimates will be able to be reported as a mineral resource or ore reserve in accordance with the JORC Code.
Link to the original release:
Upcoming and ONGOING Work Programs
GreenX is advancing a coordinated suite of exploration activities which will test the validity of the Exploration Target identified at Tannenberg, including:
- Mineralogical and desktop metallurgical analysis of material collected from archive core – Q2 2026;
- Accessing historical underground mines for scoping study-level metallurgical test work, chip sampling, as well as mapping and surveying for 3D modelling – 2H 2026;
- Collation and digitisation of historical geological, mine development, and production data – ongoing;
- Analysis of the use of seismic surveys to aid future drilling campaigns including collecting petrophysical measurements for seismic forward modelling – Q2 2026;
- Seismic survey, if appropriate – commencement H2 2026; and
- Initial drill program commencement – late 2026.
ENQUIRIES
Ben Stoikovich
Chief Executive Officer
+44 207 478 3900
Kazimierz Chojna
Investor Relations – Poland
Kim Eckhof
Investor Relations – UK/Germany
Competent Persons Statement – EXPLORATION TARGET
The information in this announcement that relates to the Exploration Target is based on information compiled by Mr Rui Goncalves, a Competent Person who is registered with the South African Council of Natural Scientific Professions, a Recognised Professional Organisation’ included in a list promulgated by ASX from time to time. Mr Goncalves is a full-time employee of MSA Mining Consulting UK Ltd, an independent consulting company. Mr Goncalves has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to the activity being undertaken, to qualify as a Competent Person as defined in the 2012 Edition of the ‘Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves’. Mr Goncalves consents to the inclusion in this announcement of the matters based on his information in the form and context in which it appears.
Competent Persons Statement – Historical Estimate
The information in this announcement that relates to the historical estimates were extracted from the ASX announcement dated 20 October 2025, titled ‘GreenX Uncovers Historical Estimate at Tannenberg Copper Project’ (original announcement) which is available to view at www.greenxmetals.com. GreenX confirms that (a) it is not in possession of any new information or data relating to the historical estimate that materially impacts on the reliability of the estimates or GreenX’s to verify the historical estimates as mineral resources or ore reserves in accordance with the JORC Code; (b) that the supporting information provided in the original announcement referred to in ASX Listing Rule 5.12 continues to apply and has not materially changed; and (c) the form and context in which the Competent Person’s findings are presented have not been materially modified from the original announcement.
Competent Persons Statement – EXploration results
The information in this announcement that relates to Exploration Results is based on information compiled by Dr Matthew Jackson, a Competent Person who is a Member of the Australasian Institute of Mining and Metallurgy. Dr Jackson is a Technical Consultant for GreenX and is a holder of unlisted options in the Company. Dr Jackson has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to the activity being undertaken, to qualify as a Competent Person as defined in the 2012 Edition of the ‘Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves’. Dr Jackson consents to the inclusion in this announcement of the matters based on his information in the form and context in which it appears.
Forward Looking Statements
This release may include forward-looking statements, which may be identified by words such as "expects", "anticipates", "believes", "projects", "plans", and similar expressions. These forward-looking statements are based on GreenX’s expectations and beliefs concerning future events. Forward looking statements are necessarily subject to risks, uncertainties and other factors, many of which are outside the control of GreenX, which could cause actual results to differ materially from such statements. There can be no assurance that forward-looking statements will prove to be correct. GreenX makes no undertaking to subsequently update or revise the forward-looking statements made in this release, to reflect the circumstances or events after the date of that release.
This announcement has been authorised for release by the Mr Ben Stoikovich, Chief Executive Officer.
Link to the original release: