Tomahawk

The Tomahawk magnetite formation is the second largest iron body after Snaefell in the Mt Woods Inlier, and is part of IMX’s 100% owned Mt Woods Iron Project.

Like Snaefell, the high magnetite content makes the Tomahawk rocks readily amenable to upgrading by magnetic separation. IMX expects this prospect will become a major asset that adds to the Company’s rapidly expanding iron ore resource inventory in the near future.

The 3.4km Tomahawk magnetic target was identified from a detailed airborne geophysical survey completed in 2011. Reverse circulation (RC) drilling testing the most intensely magnetic part of the target in late 2011, successfully intersected wide intervals of magnetite mineralisation in all 5 holes drilled. A best result of 164m @ 31.44% Fe from 31m recorded in hole THRC001.

Figure 1. Tomahawk drillhole and section location on magnetics

Table 1: RC Magnetite Intersections (Fe ≥ 20%, Intervals ≥ 10m, Internal Dilution ≤ 4m)Note: All analyses are by X-ray Diffraction (XRF) on one metre intervals

The Tomahawk magnetite iron formation occurs as a steeply dipping coarse-grained magnetite zone within a quartz-rich sedimentary host package that includes limestone and marble units. The magnetite zone ranges from 60 to 100m in true thickness and occurs below about 30m of unconsolidated sedimentary overburden. The mineralisation remains open along strike and at depth. 

Figure 2. Tomahawk interpreted geological cross section

As part of IMX’s strategy to focus on quality iron projects with the potential for development, preliminary metallurgical testwork was conducted on the RC drill samples from Tomahawk in early 2012. 

Results from initial Davis Tube Recovery (DTR) testwork are encouraging. Preliminary metallurgical assessment indicates that a concentrate grading up to 65% Fe can be achieved at a coarse grind size of 250 microns using a simple magnetic separation process. Indicative mass yields averaged 32% meaning that a significant amount of waste material can potentially be removed early in processing, which in turn will reduce anticipated capital and processing costs.  Phosphorous and other deleterious elements in the concentrate are all very low, which suggests a premium iron product can be produced. 

Further drilling and metallurgical testwork is planned to advance the prospective Tomahawk project during 2012.