Adelaide’s Investigator Resources (ASX: IVR) has updated the mineral resource estimate at its wholly-owned Paris silver project on South Australia’s Eyre Peninsula, following the completion of an infill drilling campaign late last year.
The new resource sits at 18.8 million tonnes grading 88 grams per tonne silver and 0.52% lead for 53.1 million ounces silver and 97,600t lead at a cut-off grade of 30g/t silver.
It includes an indicated component of 12.7Mt at 95g/t silver and 0.6% lead – or 73% of the total estimated resource ounces – added from infill drilling within the known footprint of mineralisation.
Managing director Andrew McIlwain said the new figures had “substantially improved” the company’s confidence in the Paris project.
“While there was some anticipation that early high grades reported from our infill drilling would improve the average resource grade, ultimately that program advanced [the project] resource by delivering 12.7Mt into the indicated category compared to 4.3Mt (or 46%) reported in the 2017 estimate,” he said.
“Drilling was designed to close spacings down to 25 metres from previous spacings of up to 100m, and allowed our inferred classification areas to [convert to] indicated, confirming that the density of drilling was appropriate to improve confidence in the resource estimate.”
Reduced cut-off grade
The new resource features a significant increase in total silver ounces over the previous estimate, largely due to a reduction in cut-off grade from 50g/t silver (which yielded an estimated 42Moz).
“With the current silver price of $35/oz being significantly higher than the 2017 average of approximately $22/oz, it was appropriate to estimate the [new] resource at the lower cut-off grade of 30g/t silver which has resulted in [the updated estimate],” Mr McIlwain said.
“The increase in tonnage substantially changes the metrics of [this project] allowing the pre-feasibility study to assess a mine life of over 10 years plus improved efficiencies, as well as supporting alternate considerations for the likes of infrastructure and renewable power supply options.”
The updated estimate will facilitate completion of the Paris pre-feasibility study in the September quarter.
The Paris silver deposit is hosted within a sequence of flat-lying, intensely altered, polymictic volcanic breccias related to South Australia’s Gawler Range Volcanics.
Mineralisation is predominantly located in the oxide to transition zones of the host breccia above a palaeo unconformity on a basement of older dolomitic marble.
It extends for 1,600m of strike length with variable zones up to 800m wide and depth to fresh rock ranging from 60m to 130m below surface.
Investigator believes the dominant soft host rock and shallow depth of the Paris deposit is amenable to open-pit mining operations and has modelled and classified the resource estimate in accordance with that assumption.