Argosy Minerals Limited (ASX:AGY) drilling is revealing better than expected lithium content over thicker brine-bearing zones at the Rincon project in Argentina’s Lithium Triangle.
Drilling has also confirmed a thick sequence of black sand in the project area, which is positive for future brine extraction requirements.
A further positive outcome of the drilling is better average magnesium/lithium (MG/LI) ratios than historical reference data.
“Positive for resource estimate”
Jerko Zuvela, managing director, said: “Resource drilling has intersected very significant thicknesses of black sand beneath the surface halite layer.
“This is very positive for our upcoming JORC resource estimate and planned preliminary economic assessment.
“Confirmation of higher average lithium brine grades in the area closest to the stage II evaporation ponds is also positive for our fast-track production strategy as we continue to progress stage II development works.”
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Argosy has been conducting two concurrent phases of drilling operations – resource exploration drilling and production well drilling.
The former is utilising a diamond drill rig to collect drill cores for porosity assessment and to obtain brine samples for resource estimation.
Production well drilling
For production well drilling a rotary drill rig is being used for the construction of wells for pumping of lithium brine into the stage II evaporation ponds.
Seven of eight planned exploration diamond drill-holes have been completed with the eighth in progress.
The holes have been drilled to a depth of 102.5 metres, to intersect a sequence of halite, clay and black sand.
The new results include an average of 446mg/l lithium in eight brine samples from 3-78 metres in one hole, with an average Mg/Li ratio of 8.2.
Another hole returned an average of 343mg/l lithium over the upper part of the hole in samples from 42 to 54 metres, with an Mg/Li ratio of 5.8.
Black sand open at depth
Drilling intersected thicknesses up to 36 metres for the upper porous halite unit and thicknesses of up to 66 metres for the deeper black sand unit, which remains open at depth.
A black sand unit in core from the Rincon project.
The black sand has relatively high drainable porosity, based on initial laboratory data, and is expected to have relatively high permeability.
Once completed, porosity data from the eight holes will be used together with the systematic brine analyses from the drilling samples to produce a JORC-compliant resource estimate.
Argosy has completed two rotary drill-holes to be used as production wells.
The first production well is at the same site as the R2 diamond drill-hole and acts as a monitoring well at this site.
This well has been operational since December 2017 and is supplying lithium brine to the stage II evaporation ponds.
The second rotary well was drilled to a depth of 36 metres, while a third production well is planned in the northern area around the R4 drill site with greater lithium brine grades.
These wells will be connected to piping to pump lithium brine into the stage II evaporation ponds.