Krakatoa Resources Ltd (ASX:KTA) has completed a reverse circulation (RC) drilling program testing lithium-caesium-tantalum (LCT) prospective pegmatites at the former King Tamba tantalum mine.
A total of 16 holes were drilled beneath high-grade lithium oxide rock samples, with 1,806 metres completed over seven days. Of the 16 holes, 13 intersected pegmatites with consistent intersections of flat-lying pegmatite logged from 70 metres deep.
This program had been expanded from the initially proposed 1,200 metres due to the discovery of a thick pegmatite of up to 39 metres downhole width underlying the 4.3% lithium oxide rock chip at the project’s Wilsons prospect.
RC drilling was the culmination of a program of outcrop mapping, sampling and mineralogical work which had defined multiple lithium mineralised targets within a broad anomalous zone.
The drilling completed to date has tested a small area within the broader 3-kilometre LCT corridor, which presents potential for additional pegmatites at depth and along strike.
Pegmatites encountered
Drilling sought to explain the source of lithium-rich greisen-altered pegmatites which were evident on surface and had been widely sampled. Hole depths ranged from 42 metres to 174 metres, with an average of 113 metres.
The 13 holes that intersected pegmatites were hosted in a mixture of dolerite and fine-grained metasediments. The pegmatites intersected at shallow depths were generally 2-5 metres thick and somewhat discontinuous along section.
Krakatoa encountered a significant pegmatite with true thickness up to 30 metres at 70-90 metres deep, underlying the full extent of the target area. There was a general trend of increasing pegmatite frequency towards the southeast of the target area.
Schematic cross section over the three main prospects showing position and downhole lithology
The mineralogy of the pegmatites showed variable proportions of quartz, feldspar and mica along with traces of accessory minerals such as fluorite and tourmaline in places.
A number of samples were noted to fluoresce orange-pink-salmon under shortwave UV light, which is often used to indicate the presence of spodumene within pegmatite samples, but it is not an exact method.
No obvious zones of bulk greisen alteration or lithium mineralisation were noted visually whilst logging, but the presence or absence of spodumene can only be definitively determined by detailed mineralogical analysis, which Krakatoa intends to carry out in due course.
All pegmatite samples will be assayed, and further work will then be targeted towards mineralised zones.
What’s next?
The samples will now be sorted and reviewed in the company’s Perth facility before being delivered to the laboratory for analysis.
While awaiting the assay results, Krakatoa’s exploration team will work on interpreting the observed geology and updating the existing 3D pegmatite model plus additional reconnaissance within the identified LCT corridor. It may also undertake geophysical logging of selected boreholes.
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