Core Lithium Ltd (ASX:CXO) has received drilling results described as “exceptional” following its exploration activities at BP33 deposit, part of the Finniss Lithium Project near Darwin.
The Australian lithium developer kicked off diamond drilling at BP33 in May, with assays now filtering through.
Three deep diamond drill holes have intersected mineralisation at depths of up to 470 metres below surface, with the orebody open at depth.
Spodumene-bearing pegmatites
A further five diamond holes have intersected variable thicknesses of mineralised pegmatite associated with the southern BP33 body at depths below any previous drilling and up to 420 metres below surface.
Geological logging of theses holes has confirmed that spodumene-bearing pegmatite extends at depth to the south with indications that thickness and grade may improve with depth.
Although the main and southern bodies are modelled as separate entities, the location of this drilling supports the idea that they are likely continuous.
Highlights
Significant intersections include:
- 66.88 metres at 1.78% lithium dioxide including 16 metres at 2.27% and 9 metres at 2.24%;
- 27 metres at 1.50% lithium dioxide including 4 metres at 2.02%; and
- 15 metres at 1.22% lithium dioxide including 7 metres at 1.70%.
The true thicknesses of the intersections are around two thirds of those shown – so a downhole intersection of 67 metres equals true thickness of approximately 45 metres.
The continuity in grade and thickness displayed, together with the position of the intersections outside or on the boundary of the current mineral resource envelope, is expected to result in an increase in the mineral resource estimate (MRE) for BP33.
Orebody “better at depth”
Chairman Greg English said: “The BP33 orebody appears to be getting better at depth with 66.88 metres at 1.78 lithium dioxide, an outstanding result.
“We are in the middle of our largest ever drill campaign and these latest results more than justify our decision to expand our exploration efforts.
“BP33 south is open at depth with the Ambient Noise Tomography (ANT) survey identifying additional targets at the deposit. The timing of these outstanding results could not have been better, with the final mining approval for BP33 expected in the coming weeks.
“These new world-class lithium drilling results reflect the confidence Core has in delivering significant resource growth from Finniss that will add to our life of mine and our capacity to materially increase lithium production from northern Australia in the future to keep up with rapidly growing global demand.”
Successful ANT geophysical trial
In May, Core commissioned Fleet Space Technologies to undertake a trial ambient noise tomography (ANT) survey at BP33 to test the effectiveness of the technique at detecting pegmatites at depth.
It has been tricky to find a successful geophysical technique for identifying the Finniss pegmatites, so the ability to target blind pegmatites is being held up as a major breakthrough in exploration for the project.
The results were “an outstanding success”, with the BP33 body imaged as a low S-wave velocity anomaly, showing excellent correlation with the pegmatite body interpreted from drilling.
Though the trial was only conducted over BP33, a number of previously unknown targets have emerged. CXO’s next step is to use the technique in untested areas and prioritise targets for drill testing.
The now-proven ability to detect subsurface pegmatites at considerable depths – at least 500 metres – will be a major boost for future exploration.
The company is confident that ANT technology is a cost-effective method of informing drilling targets.