THE SHAIMERDEN ZINC OXIDE DEPOSIT, KAZAKHSTAN

The Shaimerden zinc oxide deposit is located in northwest Kazakhstan, approximately 240 km southwest of the town of Kostanai. The deposit is located at the southern end of a fault bounded, north-northeast trending belt of Lower Palaeozoic clastic and carbonate sediments and volcanics. In the Shaimerden area the lithologies comprise Carboniferous limestones and andesitic volcanics that are intruded by small diorite and granite bodies. Upper Cretaceous sediments fill karst depressions within the Carboniferous limestone and host bauxite deposits. Overlying the whole area are 40m of Tertiary-Quaternary sands and clays. The deposit is hosted in a massive, clean Carboniferous limestone and has resulted from the in-situ oxidation during the Triassic - Cretaceous period of a body of massive sphalerite mineralisation. The deposit occurs within a weathered depression measuring 450m east-west, 150m north-south with mineralization occurring to a depth of 240m below the surface topography. The mineralization has been sub-divided into 5 categories based on macroscopic and microscopic studies of the ore. These are: Massive hemimorphite (calamine)-smithsonite – intimately related to the massive sulphides and varies from a massive fine-grained ore to a brecciated vuggy rock; Stony ore - a dark green to dark red weathered, competent and sometimes friable material with a relict breccia texture. It is an intermediate weathered material between the massive hemimorphite-smithsonite and the mineralized clays; Mineralized clays – characterised by their grey/green colour and high percentage of gritty and fragmental material. The zinc occurs mostly as small fragments of hemimorphite and smithsonite and partly as clay minerals; Massive sulphides – preserved in the centre of the orebody and consisting mainly of sphalerite with very minor amounts of galena and pyrite; Mineralized limestone – occurs along the margin of the weathered trough and consists of intervals of mineralized clays within the limestone. A final resource of 4.6Mt @ 21.1%Zn using a cut-off grade of 5%Zn has been defined, with a reserve of 4.28 million tonnes at a grade of 20.9% Zinc in the proven and probable categories.