GreenX Metals (ASX: GRX) has marked a shift from historical archive work to active field exploration by defining a large exploration target at its Tannenberg copper project in Germany.
The target ranges from 144 million tonnes to 279Mt at 0.9% to 1.4% copper and 15 grams per tonne to 21g/t silver.
That range equates to contained metal of 1.3Mt to 3.9Mt copper and 69.4 million ounces to 188.4Moz silver.
The estimate remains conceptual under the JORC 2012 code, with further exploration required before any mineral resource can be estimated.
Modern Deposit Model
GreenX has taken a broader modern view of the deposit by including potential mineralisation in the hanging wall and footwall units above and below the shale.
That approach reflects mining experience in Poland, where KGHM Polska Miedź operations recover much of their mineable copper from the same footwall sandstone and hanging wall limestone units.
The resulting exploration target is materially broader than the historical view of the system, with a modelled mineralised thickness of 1.7m to 3.3m compared with the 20 centimetre to 60cm shale-only thickness used in a 1940 historical estimate.
The target draws on a long history of drilling and mining across the Richelsdorf Mining District, where a 95-hole drilling campaign completed between 1935 and 1938 provided the geological basis for three Kupferschiefer copper mines within the Tannenberg licence area.
Those mines—Reichenberg, Wolfsberg and Schnepfenbusch—operated from the late 1930s and in some cases into the mid-1950s.
Archiving Completed
GreenX has digitised and integrated that historical drill hole database into its geological models, while also using 1980s work by St Joe Explorations that first indicated wider mineralisation beyond the shale horizon.
The company has also completed a substantial archive core program after discovering drill core retained for more than 40 years in the archives of the Hessian state geological agency, with 4,389m of archived core now relogged and 2,368 new samples taken.
That work validated historical copper and silver grades around the historical mining areas and showed the mineralisation persists several kilometres away from the old mines.
Chief executive officer Ben Stoikovich said the new target is the product of 18 months' 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,” he added.
“The size of the potential copper endowment at Tannenberg […], in the same geological formation of the world-class Polish deposits, justifies continued investment and exploration.”
Next Work Programs
GreenX will now move into a series of field-based and technical programs designed to test the exploration target.
Near-term work includes mineralogical and desktop metallurgical analysis from archived core, together with evaluation of seismic survey options for future drilling campaigns.
The company plans to access historical underground mines in the second half of 2026 for scoping study-level metallurgical test work, chip sampling, mapping, and surveying for 3D modelling.
An initial drill program is targeted to commence late in 2026.
