Krakatoa Resources (ASX:KTA) reports recently received resource drilling assays have recorded multiple ‘broad’ zones of rubidium at the King Tamba Critical Metals Project in Western Australia.
The company reports assays have been received from the recent King Tamba reverse circulation (RC) drilling include an ‘exceptional’ intersection from drillhole DAL005 totalling 70m @ 0.23% RbO2 from 82m downhole.
This intersection was partially reported as 34m @ 2,183ppm Rb in August, and has now been expanded with the receipt of further assays.
Krakatoa drilled 32 RC drillholes for a total of 3,045m during May and June this year, and the program targeted a suite of mineralised pegmatites enriched in rubidium, tantalum, caesium, niobium and lithium, and was designed to infill existing drilling to a nominal 40m by 40m spacing to allow calculation of a maiden mineral resource.
The company submitted a total of 1,416 samples for analysis in mid-June, with a first batch of 553 results reported in late August, and the remaining 863 results have been received.
Krakatoa reports rubidium was the primary target of the drilling with previous work having returned ‘highly’ anomalous values over a large areal extent.
The thickness of the intersections, combined with the continuity of mineralised units in the company’s geological modelling is ‘promising’.
Samples with rubidium grades in excess of 1,000ppm have been returned over intervals with geological continuity.
Intersections of note to Krakatoa include drillhole DAL029, which was the southernmost drillhole in this program, and the most southerly hole drilled on the King Tamba project.
DAL029 intersected 7 mineralised pegmatite bodies with a cumulative 28m thickness over the 102m total length, including 1 which returned 3m @ 0.45% RbO2 from 66m downhole.
This intersection returned the highest individual rubidium result of the program with 1m from 67m to 68m downhole assaying at 0.7% RbO2, 0.47% Li2O and 0.16% Cs2O.
The company says these results were obtained from a narrow pegmatite body 3m wide, but with markedly different chemistry from those around it.
It also notes DAL029 is surrounded by ‘blue-sky opportunity’ with no drilling to the east, west or south, and the nearest hole to the north is 160m away.
Krakatoa intends to follow-up this intersection with further drilling.
Another intersection noted by the company was drillhole DAL008, which returned 1m @ 0.42% Ta2O5 and 0.08% Nb2O5 within the differentiated quartz-rich core of a wider pegmatite unit.
The elevated tantalum levels are notable for being an order of magnitude higher than any other sample from this drilling program.
Previous mining activities conducted at King Tamba were focused on tantalite from the quartz-core of differentiated pegmatites and Krakatoa is alert to the possibility of discovering further tantalite lodes whilst exploring the project.
The company reports this aligns with the drillhole DAL002 that returned a maximum of 0.85% Li2O, an average of 0.45%Li2O between the 62m to 68m interval.
Krakatoa reports a ‘cohesive’ geological interpretation and model is forming at King Tamba with consistent wide zones of ‘elevated’ rubidium observed in multiple stacked pegmatite lenses with a sub-horizontal attitude.
Occasional vertical or steeply dipping pegmatites are also interpreted, however the company suspects these are likely underrepresented by the drilling to date which has been composed mainly of vertical holes.
Within the pegmatites exist differentiated fractions which can have higher metal concentrations.
Krakatoa says although these form a small percentage of the overall volume, their high tenor makes understanding its distribution important.
Work to confirm the rubidium deportment is ongoing, and initial indications from correlation of geological logging to geochemistry suggest elevated rubidium is contained mainly within mica in pegmatite.
Moving forward, Krakatoa intends to complete structural geology modelling and mineral deportment work at King Tamba before finalising a maiden Mineral Resource Estimate (MRE) later this quarter.
The company believes the potential to discover further mineralised pegmatites at the site is clear, potentially including zones which are enriched in tantalum, lithium and caesium.
In late 2021, Krakatoa defined an Exploration Target based on historical drillholes of between 1,470,000t to 3,185,000t, with estimated grades of Rubidium (500ppm to 2,000ppm), lithium and niobium, tantalum, tin and tungsten.
The potential quantity and grade of the Exploration Target is ‘conceptual’ in nature and is an approximation.
The company reports insufficient exploration to estimate a mineral resource and it is uncertain if the results of the current drilling will result in the estimation of a mineral resource, despite being an objective of the recently completed drilling program.
The modelled pegmatite which constituted the exploration target has 156 historical holes (5,071m) and 11 holes (1,066m) drilling by Krakatoa in 2017.
Only 4 elements were assayed within the historical holes, and the company expanded the analysis with a focus on the rubidium, lithium, niobium, tantalum, tin and tungsten across the area.
Krakatoa is currently preparing an ‘aggressive’ program of geochemical sampling and drilling for 2023, following the release of the MRE.
The King Tamba Project is located approximately 70km from Mt Magnet in Western Australia, and the project sits in the Dalgaranga pegmatite complex first discovered in the early 1960s.
Historic mining on the complex by various companies mapped the pegmatites over an area spanning at least 2km by 0.4km, and to the southeast an outcropping pegmatite swarm continues south over a northeast-southwest strike length of roughly 500m up to 250m wide, increasing the prospectivity of finding additional mineralised pegmatite bodies.
The extension of the southern pegmatite swarm and mapping of the systems to the south is an ongoing part of the exploration program for Krakatoa, and other areas of interest identified using geophysical and Aster imagery have identified priority target areas.
Krakatoa Resources is an emerging and diversified ‘high-value’ critical metal and technology element company catering to the exponential demand spawned by electrification and decarbonisation.
The company has a portfolio of assets associated with copper-gold exploration in the Lachlan Fold Belt of New South Wales, and multi-element metals including rare earths, nickel and heavy mineral sands in the Narryer Terrane, Yilgarn Craton in Western Australia, and critical metals at Dalgaranga, also in Western Australia.