Leboam Holdings (Pty) Ltd (in judicial management) (“Leboam”) is a mining entity that operates Mowana Copper Mine (“Mowana Mine”) situated at Dukwi, in the North-East of Botswana. Leboam has been in judicial management since December 2018.
Cradle Arc Plc (“the Company”) was the 100% shareholder of Cradle Arc Investments PTY Limited (“CAI”). CAI is the parent company of Leboam Holdings (Pty) Ltd., the owner of the Mowana mine.
During the course of the Liquidation, the Joint Liquidators were contracted by a party interested in acquiring the Company’s shareholding in CAI. The Joint Liquidators completed a sale of the Company’s shareholding in CAI to Max Power Limited (MPL), unconnected party, on 5 October 2020 for 50,000 US Dollars.
Following its acquisition of the CAI shares, MPL contacted the JM and with the support of LHL’s key stakeholders proposed a new Scheme of Arrangement. The Scheme of Arrangement was approved by the High Court of Botswana on 9 December 2021.
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Summary:
The Mowana Copper Project is hosted within north-northeast striking, steeply east dipping carbonaceous and argillaceous metasediments of the Matsitama Metasedimentary Group which are enclosed within foliated granitoids of the Mosetse Complex.
Hypogene sulphide mineralisation occurs within sub-vertical epithermal quartz-calcite vein breccias containing predominantly chalcopyrite + pyrite ± galena and sphalerite mineralisation. Hypogene mineralisation is capped by secondary oxide and supergene copper enrichment up to depths of approximately 50m and 150m below surface respectively. This in turn is overlain by Phanerozoic Karoo Supergroup siltstones, conglomerates and local tillite over the north and west areas of the deposit with depths varying from 1 to 90m. Regolith cover over the southern extent of the deposit generally consists of shallow (1 - 3m) clay rich black soils.
The metasediments hosting the deposit occur parallel to and within the northern extent of the 200km long north-northeast trending regional Bushman lineament exhibiting thicknesses variable between 200 to 400m mostly due to large scale pinch and swell amplitudes of up to 600m. However, the contact between the footwall sediments and the western granitoid has not been intersected in any of the historical or recent drilling.
Four deformation periods have been interpreted within the project area, the strongest and most significant with regards to veining and mineralisation being the deformation that initiated the regional scale Bushman lineament. A final post mineralisation deformation event produced a number of northeast trending parallel faults transecting the mineralised breccia at a low angle into three main zones of roughly equal length. From north to south, they are Mapanipani North, Mapanipani and Bushman sections.
The footwall argillaceous metasedimentary rocks exhibit alteration mineralogy and textures of retrograde regional greenschist metamorphism from either a higher grade lower amphibolite facies or arguably a more localised thermal metamorphic hornfels. In the Mapanipani and Bushman sections, localised but well developed talc/serpentine alteration from metasomatism occurs within dolomitic lithologies.
Sulphide bearing veins are generally spatially associated with carbonaceous (graphitic) argillites and are composed of quartz+calcite ± K feldspar in varying ratios with three stages of quartz veining having been identified. Only the second vein generation bears Cu, Pb & Zn sulphides. Areas of intense vein stockworks have been termed breccias and form the copper deposits. Photo 3.2 shows a block of typical brecciated oxidised ore.
Fluorite and barite are rare but locally evident. Pyrite + chalcopyrite occur mostly as semi-massive patches and coarse aggregates. Galena±sphalerite occurs locally usually associated with fluorite in discreet zones generally separate from chalcopyrite mineralisation which it slightly post-dates.
Regarding veining and mineralisation, the graphitic argillite (Photo 3.3) is the most significant lithology of the metasedimentary assemblage.
It is moderately to strongly graphitic, fine to very fine grained, black to very dark grey, laminated to fissile. The unit may grade into both cleaner limestones and more argillaceous pelitic rocks. Lamination is at a mm-scale ranging from planar to highly contorted and it commonly hosts fine grained pyrite in disseminations and small irregular stringers. Most of the intervals identified as carbonaceous phyllite or graphite schist form either the immediate wallrocks to the mineralised breccias and/or host moderate to high density veining forming a graphitic breccia.
The distribution of this unit is somewhat irregular, since it can form a relatively thick envelope to the breccias, be absent or entirely replaced by the breccia units up to their contact with the host limestone. This is also evident in cross section where the graphitic unit may occur in the upper part of a section and is absent lower down and/or vice versa. This is probably due to the unit having a pod like or lensoidal nature both along strike and down dip throughout the metasedimentary assemblage due to deformation. Its highly ductile nature would have led to this unit absorbing a lot of the strain under deformation.
Similar juxtapositions are seen with other lithologies in that, in the North Pit, limestone is on the hangingwall side of the orebody, whereas in the South Pit it is on the footwall.
In terms of the current Mowana pit, evidence suggests that the South Pit has a higher copper grade, less graphite, but the sulphide mineralisation is deeper, whilst the North Pit has a lower grade, but with more graphite, although the sulphides are nearer surface. In essence, the graphite is a problem for processing (although the use of a different collector may reduce this affect), but the very visual nature of it should allow avoidance of the worst of this material during mining.
Therefore, in summary, the near surface tenor of the orebody at Mowana is characterised by the mixed nature of oxide and supergene enrichment extending from surface to a maximum depth of approximately 70m. With increasing depth supergene chalcocite mineralisation continues and dominates with a nominal transition to Chalcopyrite-bearing hypogene mineralisation at around 150m below surface.