Patagonia Lithium (ASX: PL3) has reported a maiden inferred mineral resource estimate of 3.8 million tonnes lithium carbonate equivalent (LCE) for its flagship Formentera lithium brine project in Argentina.

Diamond drilling of 1,499 metres produced the estimate alongside 717,000t of lithium metal in situ, confirming Formentera as one of the best undeveloped projects in Argentina with superior brine volumes, specific yield, high porosity and lithium grades.

The company estimates a 15-year mine life at 10,000tpa for the project.

Block model

The resource includes 173,000t LCE, with calculated mean sample values of 461.6 milligrams per litre (mg/L) lithium and 945.7mg/L magnesium applied as default values for unestimated high-porosity salar blocks in the block model.

Values of 186.4mg/L lithium and 729.8mg/L magnesium have been applied for unestimated salar blocks.

Lithium grades as high as 1,122 parts per million (ppm) have been measured in the subsurface and 580ppm at 360 metres depth from a drill hole at Formentera Well Two.

Exceeded expectations

Patagonia executive chairman Phillip Thomas said the maiden resource exceeded expectations.

“The total volume, specific yield and high concentration of lithium leads us to believe we have a valuable project to be developed,” he said.

“We have only drilled four wells at Formentera and there is significant exploration and upside potential to expand this resource as we continue to drill out the high-porosity zone and the Cilon concession.”

Next stages

Mr Thomas said the results would allow Patagonia to proceed to the next stages of the project.

These include submitting a permit application for a 1,000t Ekosolve direct lithium extraction demonstration plant, drilling the fifth exploration well and planning production wells once borehole magnetic resonance surveys have been completed.

“We have also prioritised a scoping study for Formentera and a definitive feasibility study using the results from further exploration,” he said.

“We are confident we can unlock additional resources and value for our shareholders.”

Project location

The Formentera project covers 19.54 square kilometres in Jujuy province within Argentina’s famed lithium triangle, across two mining leases owned by Patagonia subsidiary Patagonia Lithium Argentina SA.

The leases cover the complete salt lake near Jama township, approximately 1km from the Chilean border, with the lowest point at approximately 3,900m above sea level in a large drainage area.

The basin drains lithium-bearing volcanic rocks from the nearby Zapaleri volcano, whose summit marks the borders of Argentina, Bolivia and Chile.