Khartoum - Overview
Located approximately 100km south-west of Cairns in North Queensland, the geology of the Khartoum tenement is dominated by highly fractionated coarse-grained granites with excellent potential to host economic tin-tungsten mineralisation. The project area covers a Late Carboniferous-Early Permian felsic intrusive (the Elizabeth Creek Granite), containing over fifty tin, tungsten, molybdenum and gold occurrences. Historic production is estimated to be 15,000t tin.
Outcropping tin mineralisation is associated with 107 recognised greisen zones covering a combined area exceeding 50km2.
Exploration at this early stage indicates the potential for Khartoum to be a new world class tin deposit, with a conceptual tonnage/grade potential of 80 – 100 million tonnes at 0.2%-0.3%Sn*.
Khartoum was identified by the Company’s prospectivity modelling as highly prospective for tin and tungsten mineralisation and moderately prospective for gold mineralisation.
Regional mapping and soil sampling initially identified a 9km by 3km zone of highly anomalous tin geochemistry. Reconnaissance exploration identified fifteen key areas with soil values up to 1.8% tin.
Key target areas relate to zones of greisen alteration. The greisen zones may be flat-lying / shallow dipping, steeply dipping and traceable for up to 1km in length, or forming sub-vertical 'pipes' (average width approx. 50m) and exposed as prominent topographical features. Results from rock chip sampling indicate that tin occurs as disseminated cassiterite in greisen and to a lesser extent in quartz veins.
Channel sampling was completed in the second half of 2007 over selected greisen bodies to assess potential grade and widths of tin mineralisation in the near surface. The sampling targeted twelve greisen zones where rock chip samples were collected over metre intervals and composited into 5m samples. Most samples came from subcrop and appear representative of in situ greisen pipe. Results were very encouraging with six of the ten pipes sampled averaging greater than 0.1% tin. Best results included 5m at 1.0% tin, 35m at 0.38% tin and 40m at 0.30% tin.
A six hole initial scout drilling program was completed in December 2007, just before the onset of the wet season. Tin mineralisation was intersected in all six holes from an area with a 2,500m strike extent and over wide intervals from surface to a depth of 132m with grades between 0.13% and 0.26% tin intersected. Narrow zones of higher grade were also intersected. Best results include 104m at 0.21% tin from 12m and 34m at 0.26% tin from 99m.
Similar zones of mineralisation have been mapped in the 2.8km by 2.5km area, which along with several tin soil anomalies within the larger 3km by 9km area, provide numerous new targets for future resource drilling. Spectral processing of satellite imagery was used to highlight the considerable potential to increase the scale of the project within the Company's tenement, outside of the area defined by the initial exploration.
Initial metallurgical testwork undertaken on diamond drill core of fresh greisen mineralisation indicate a combined tin recovery from gravity and flotation of 71%. This result is considered highly encouraging because significant improvements are likely to be made with modification to grinding and flotation circuit parameters. Mineralogical studies indicate the cassiterite is generally of fine grain size, free from sulphide and contains only trace stannite (an uneconomic tin mineral).
By the end of 2008, detailed geological mapping and channel sampling had identified 107 greisen zones containing significant tin mineralisation. Sampling to date has totalled 1373 channel samples (each sample represents 5m length) in 309 traverse lines, 65 rock chip samples and 749 soil samples.
Exploration to date suggests a mineralised system with a conceptual tonnage potential of 80 - 120 million tonnes, averaging 0.2% - 0.3% Sn based upon the areal extent of greisen tin mineralisation discovered within the project area, and the reported results of the Company's geological mapping, sampling and drilling program.
*There has been insufficient exploration undertaken to define a mineral resource and it is uncertain if further exploration will result in the determination of a mineral resource.
