RE: Copper in the ground Worth 1.85 Billion to GLR11 Oct 2022 12:00
The Luansobe deposit occurs within quartzites in the same host sequence as Mufulira, also on the SW limb of the Mufulira Syncline, but 6 km to the NW. Resources are quoted at 8.4 Mt @ 1.6% Cu 0.13% Co (Selley et al, 2005), or 5.6 Mt @ 1.58% Cu Total, 0.76% Cu Acid Soluble (Wimberley et al., 2011 for Mopani Mines).
The host sequence comprises a 0 to 70 m thick Footwall Formation composed predominantly of grits and poorly bedded conglomerates, with silty partings. The grits grade up into feldspathic to argillaceous quartzite. The thickness varies with the basement topography (Groen, 1961).
The overlying Ore Formation is 50 to 110 m thick, and commences with the 15 to 30 m thick E Quartzite, which is moderately well-bedded, feldspathic and argillaceous, grading to a fine to medium grained and gritty variety, and containing beds of grit, conglomerate and sandstone, with argillaceous partings. The overlying D Quartzite has a gradational contact, and is 6 to 8 m thick. It comprises massive to distinctly bedded, light grey, gritty and feldspathic quartzite, grading upwards into a greywacke. The succeeding C Quartzite is similar to the underlying D, but is locally dark, due to minor carbonaceous material and pyrite. This is overlain by a 1.5 m dolomitic shale, termed the "Mudseam", followed by the 9 to 20 m thick B Quartzite, which is similar to the C and D Quartzites, and is, in turn, overlain by the 8 to 20 m thick Lower Dolomite and Shale. The formation is capped by the 6 to 14 m thick A Quartzite, similar to the other quartzites, although it contains numerous cavities filled with anhydrite.
The Hangingwall Formation is made up of the 20 to 33 m thick, massive to poorly bedded Argillaceous Quartzite, comprising an argillaceous quartzite to sandy argillite, with shale partings, a local pink dolostone and an uppermost 5 m of siltstone with argillite partings. The overlying 5 to 10 m thick, light grey Marker Grit is a pitted, glassy feldspathic quartzite with quartz and feldspar grit, followed by the 15 to 27 m thick, massive to poorly bedded, grey, Sandy Argillite, and then the 25 m thick, light grey, poorly bedded and hard Glassy Quartzite (Groen, 1961).
Sulphide mineralisation occurs as pyrite, chalcopyrite, bornite, chalcocite and sphalerite. Pyrite is dominant from the Mudseam to the top of the A Quartzite. Pyrite with chalcopyrite and local chalcocite are found in the C Quartzite; chalcopyrite, bornite and chalcocite in the D Quartzite, and only chalcocite in the E Quartzite (Groen, 1961).
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