Alta Zinc Ltd (ASX:AZI) (FRA:8EE) has been as much as 25% higher in early trading on updating the mineral resource at its Gorno zinc-silver-lead deposit in northern Italy with the asset’s contained resources increased.
Overall, the project’s total mineral resource tonnage is now 2.4 times greater than previous estimates, while the zinc grade is 40% higher than Alta’s 2017 mineral resource estimate.
The upgrade means the Gorno deposit now hosts 3.3 times more contained zinc metal than previously thought, of which 60% lies in the indicated category.
Investors have responded positively to the news with shares as much as 25% higher to A$0.10.
Ultimately, the updated resource will underpin future mining and metallurgical studies, fast-tracking a feasibility study and Gorno’s development as one of Europe’s premier zinc-lead-silver deposits.
A table outlining the updated mineral resource, reported with a 1% zinc cut-off grade.
“More than three-fold increase” in zinc
Alta Zinc managing director Gerraint Harris said: “Alta shareholders have now been rewarded by this very positive mineral resource upgrade, based on results from the recent drilling programs in the new areas of Pian Bracca and Ponente.
“The outcome is a more than three-fold increase in the amount of zinc metal and a more than 40% increase in the global metal grades contained in the mineral resource estimate for the Gorno deposit.
“This is partly due to an increase in the thicker and higher-grade mineralisation, found in the Pian Bracca corridor and at Ponente.
“We have been able to achieve this result with only 15 months of drilling by identifying outstanding drill targets, of which there still remains an abundance, close to or within the network of existing underground workings which offer cost-effective and efficient year-round drilling positions with zero environmental impact.
Updating mineral resource
As it set out to update Gorno’s mineral resource, Alta Zinc embarked on an extensive exploration campaign.
The explorer recently drilled 85 diamond core holes, totalling 6,231 metres, and 34 channel samples from underground workings over 15 months, adding an additional 4.5 million tonnes of mineral resources at a 1% zinc cut-off grade.
This equates to 721 tonnes per metre drilled and almost four times the tonnage yield of the 2017 mineral resource estimate, which was calculated at 188 tonnes per metre.
Alta chalks the improvement up to its deepened knowledge of the deposit’s geology, leading to effective target selection and efficient drilling from pre-existing underground development.
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What’s next?
Promisingly, Gorno’s mineralisation remains open in all directions outside of the mineral resource estimate, with numerous step-out targets still to be drill tested from current underground development.
Alta intends to outline the large-scale potential of Gorno in a dedicated exploration target announcement in due course.
In the meantime, drilling remains ongoing, focusing on mineralisation outside of the updated mineral resource estimate (MRE). Results will be released to the market as assays become available.
Speaking to the exploration and mineral resource update, Harris continued: “Our operational success is largely due to the strength and efforts of our Italian staff, and our Italian mining and drilling contractors (Edilmac SRL) who have tirelessly and professionally worked to make the Gorno deposit the success that our municipalities and the Lombardy region in Italy deserve.
“We are currently drilling beyond the limits of our MRE into both step-out and new areas to continue to grow our resource base, notwithstanding that we now have a substantial resource inventory to support future feasibility studies.”