Kashitu is situated 7km south-east from the historical Kabwe Zn-Pb mine and processing plant, and immediately adjacent to and south of the town of Kabwe, in Zambia which is 140km north of the capital Lusaka.
Geology
The prospect is underlain by Neo-Proterozoic carbonate units of the Katanga Supergroup which form a west-northwest plunging synform. North-east trending structures within the north-west trending stratigraphy are thought to control the development of the Kabwe massive sulphide ore bodies, while disseminated and vein-type mineralisation is found to a lesser or greater degree throughout the entire syncline.
Mineralisation
There are several target types at Kashitu, including:
- Surficial accumulations of Zn-Pb-Ag and supergene enrichment associated with the near-surface karst interface, varying between 0-3m depth and ranging up to 7.7% Zn
- High grade willemite veins of limited extent, but grading up to 30-50% Zn
- Wide intervals of medium to low-grade disseminations of sphalerite and willemite associated with dolomite host rock, typically averaging 1-3% Zn, but with sub-intervals containing considerably higher grades
Limited surface mining in the area exploited a discordant N-S lenticular willemite body roughly 30m x 3m and grading up to 30-50% Zn. This operation was mostly illegal in nature and progression was likely hindered by the high-water-table.
Historic Exploration
Multiple phases of drilling (including rotary air blast RAB, reverse circulation RC and diamond) have all targeted the discovery of deep-seated massive-sulphide Kabwe-style orebodies. While no massive sulphide lenses were discovered the drilling identified large zones of disseminated mineralisation, localised areas of veining and further defined areas of surface enrichment covering an area of 1.2km x 0.3km. Highlights include:
- 170 RAB holes drilled by BHP defined a shallow 300m x 250m zone of anomalous zinc > 5% within a wider halo of zinc >1% from surface to 2-3m depth.
- 33 RC holes subsequently drilled by BHP, confirming an ENE trend of anomalous zinc with widespread disseminated mineralisation (1-2% Zn) and localised vertical pods and veins of mineralisation with up to 5-20% Zn. The best RC hole was KRC5, with an average grade of 2.42% Zn from surface to EOH at 60m, including intersections of 7m @ 4.3% Zn from surface, and 3m @ 12.7% from 49m, with the hole ending in mineralisation.
- BHP drilled four deep diamond holes across the E-W extent of Kashitu, the best holes were KDH2 and KDH3, drilled 150m apart. KDH3 intersected 227.3m @ 2.57% Zn from surface including 7m @ 6.7% Zn from 172m, with further short high-grade intervals, ending in mineralisation. KDH2 intersected 236m at 1.16% Zn from surface.
Billiton terminated the project due to the closure of the Zambian office in 1999, and not because of technical reasons.
Project Potential
Potential exists for a large (+50Mt) medium to low grade (2-5% Zn) open-pittable Zn silicate resource, with further potential for a relatively small (0-5Mt) high-very high grade (>25% Zn + Pb) lens/vein deposit of Kabwe style mineralisation in the area, in addition to the potential for recovery of zinc-rich surficial deposits.
