Li – Ta – Nb – Rb – Sn
Murchison Province WA
The Project contains the Dalgaranga Open Pit where historical open pit production of 6,434kg of Ta2O5 occurred between 2001-2003 and numerous tin, tantalum and niobium workings have been documented.
The Dalgaranga Greenstone Belt is about 50km long and up to 20km wide and contains gold mineralisation (Dalgaranga gold mine), a zinc deposit (Lasoda), graphite deposits, and occurrences of tantalum, beryllium, tin, tungsten, lithium and molybdenum related to pegmatites.
The current project comprises 5 granted tenements (E59/2389, P59/2082, 2140, 2141 and 2142) with a one under application (E59/2503). Collectively they cover approximately 43 km2.
In early 2023, the Company announced a maiden mineral resource estimate of over 5Mt with 0.14% Rubidium oxide with Lithium credits. In 2016, the company acquired 100% interest in P59/2082 the area which encapsulated the remnant mining activities targeting Tantalum, Tin and Lithium. Additional tenure was secured in 2017 and more recently in 2021. With the continued advancement of an electrified world and the demand for REEs and critical metals including Lithium and Rubidium King Tamba has become an important asset for the company. The Company is collating all historical open file drilling and surface geochemical file data into a geospatial database. Detailed historical geology mapping has been digitised and 3D modelling the pegmatite bodies is underway. This work aims to define to define structural controls on the pegmatites in the main mine area for new drill targets and to define new where pegmatites are either are untested or could occur under shallow cover.
The project is prospective for Critical metals Tantalum, Lithium, Rubidium, Tin and Niobium.
The Dalgaranga Belt is continuous with the Warda Warra (Greenstone) Belt and the greater area is a known tantalite province. The regional structural grain is N-S and NE-SW striking. The greenstone belts comprise mafic and ultramafic flows, BIFs and mafic intrusions. Metasediments and felsic volcanics occur in the southeastern part of the belt and metamorphic grade ranges from greenschist to amphibolite facies. Swarms of pegmatites intrude in the most northerly part of the belt. Laterite, colluvium and skeletal soils blanket a large part of the area.
Locally at King Tamba, mapped pegmatites occur over an area spanning 2.5 x 1 kilometres.
They intrude a metadolerite and foliated clastic metasediments and knotted schists which are folded around northeasterly trending fold axes.
In the main historical Tantalum Mine area, the pegmatites are better developed within the metadolerite unit, many have a NE – NNE orientation, similar to the apparent axis of the antiform and regional structures; a possible targeting vector. The historical reports describe 2 main pegmatite orientations. The “open pit vein and those to the south” intrude parallel to the folded sediments and, are usually 1-2 metres wide although thicken near the mine. The “Airport Vein” set is almost orthogonal with a northwesterly strike and southwest dip of 15-30°. The principal vein (5-10m thick) of this set has a flat dip for 170m, then steepens and thickens (up to 40m) and extends towards the open pit, terminating abruptly.
To the southeast, a pegmatite swarm named the “Dalgaranga South pegmatite swarm” by the geologist who mapped them (Peter Haydon) in 2012-13 continues south of P59/2082 onto P59/2142 and E59/2503. They crop out over a NE-SW strike length of roughly 500 metres by up to 250 metres wide and consist of numerous thick bodies up to 50 metres wide. Some feature shallow workings and none have been drilled to date.
King Tamba is an exciting project for Krakatoa as it contains a basket of unique critical metals comprising of rubidium, lithium, tantalum, niobium and tin. The Mineral Resource estimate was established focussing on the Rubidium component, which is hosted in a series of horizontally stacked pegmatite system. The Resource utilised many of the historic drillholes which were originally drilled to target only tantalum and niobium mineralisation only. Krakatoa extended the resource to a wider area by incorporating these historical drillholes with company drilled holes within the resource area.
The current JORC mineral resource stands at 5 million tonnes at a grade of 0.14% Rubidium oxide and 0.05% lithium oxide as shown in Table 1 below:
Mineralisation starts from surface and is highlighted by thick zones of pegmatite (upto 70m recorded). It remains open in all directions and additional zones of pegmatites have been interpreted within the license area.
Locally the pegmatite veins consist primarily of quartz, microcline, albite and muscovite with beryl and tourmaline as accessory phases. Some of the thicker pegmatites are zoned with a quartz core and feldspar margins. Tapiolite and tantalite and minor microlite were the tantalum- bearing minerals mined here with tin (as cassiterite) and up to 2% tungsten noted. Niobium also occurs within tantalite. Zinnwaldite and lepidolite (lithium-bearing micas) have been noted in some pegmatites within P59/2082. Lepidolite is the main Rb bearing mineral and can contain up to 3.2 weight % rubidium.
The first documented proper exploration comprised minor shallow percussion and auger drilling in the 1960. The projects main exploration and development phase occurred from 1999 to 2003. In 1999 Australasian Gold Mines (renamed Tantalum Australia Pty Ltd in 2002) commenced close-spaced shallow resource drilling. They defined an exploration target of 12Mt of tantalum bearing pegmatite, (17/08/2000, ASX Announcement). Furthermore, the exploration completed by Australasian determined that the tantalum bearing pegmatites are stacked vertically to a depth of at least 100m. Mining of the project was completed via an open pit for Ta from 2001 to 2002. Processing was undertaken via a pilot plant and finished in 2003. The mine was placed on care and maintenance in 2005 and has partially been removed since.
Historical mining production records are inaccurate, a 2013 estimate (Hayden) was that about 180kt of ore had been mined. Most but not all of this has been processed for a yield of around 27t of Ta2O5. A total of 18.56 tonnes of beryl ore at 10.858% was additionally mined from pegmatites for 2,015t of beryl recovered between 1961 to 1971.
After tantalum mining ceased the main exploration was done in 2011-2013 by Meridian 120 Mining. They completed a thorough data compilation, detailed mapping and rock-chip sampling of 3 areas outside P59/2082 and lag and soil sampling over specific areas. This work defined a number of new Ta-Nb-W-Sn anomalies some of which remain open and warrant extending. This work requires a detailed evaluation and Rb was not part of the assay suite. The Southern Pegmatite swarm was recommended further work and notably, there are no drillholes in this area.
Historically the concerted exploration effort concentrated on the main Mine area and little work was done outside it. Since cessation of mining, limited exploration has defined strong surface geochemical anomalies and numerous areas of pegmatites that require further evaluation. Besides KTAs limited work in 2016-17 no historical work focussed on rubidium. The project is clearly under-explored, the historical drilling was very shallow as it mainly focused on defining shallow open pitable resources in the mine area. After completing the data synthesis and evaluation KTA will commence field programs to define drill targets, starting with the Southern Pegmatite Swarm.