The assessment of the target oxidised iron material, occurring in the weathered crust of the Kalia area is based on the results of exploration drilling and geological mapping. This work has identified three types of oxidised iron ore within the Kali Iron Project
1. Massive iron ore of the “Haematite – Goethite” type Bedded Iron
2. Oxidised ores of "Canga" type;
3. “Detrital” ore;
Details of each ore type are expanded upon below.
Type 1
Typically a surface cap rock or “cuirassed” layer is present.
These ores are developed in a stratigraphic position above the primary BIF horizons. They represent the classic massive haematite – goethite iron ore material. On the surface a dense cap rock or cuirassed layer has been formed that becomes less cemented gradually the deeper from surface. The rocks represent dense and poorly-cemented small-debris and detritus breccias with sandy and clayey cement. The share of clayey material in the matrix increases with depth. These ores frequently contain debris of differently oxidised ores and sometimes debris of barren rocks and quartz. A decrease of the size and amount of debris fragments is observed with depth.
The lower boundary of this type of iron ore occurs where relict but oxidised BIF can be identified where leaching of silica is incomplete (structural eluvium). The thickness varies in from 4-5 m to 60 m and possibly more. Actual thickness is determined by local geomorphology, with the greatest thickness developed where plateaus are developed and erosional rates are low.
Type 2
These ores represent dense and solid rocks of dark-brown and reddish-brown colours. They have been formed by the erosion of massive iron oxide and BIF units and redeposited downslope. The structure of these ores is breccial, cavernous and sometimes massive. Debris and boulders within the canga are angular and poorly rounded. Debris of medium size prevails, nevertheless, large debris and boulders of a size up to 1.5-3.0m are found. Debris consist of oxidised ores of different composition; haematite, goethite, magnetite-haematite, BIF and minor greenschist. The breccias have been re-cemented with an iron rich matrix to produce a cap rock like product.
The most extensive areas of these ores were mapped in the north-west of the Kalia I. The properties of these deposits change significantly in lateral direction in terms of both, the size of clastic material and the share of ore debris in the rock. The thickness of canga ores varies from 3.0 to 18.0m, with typically the greatest thickness close to the primary source of the mineralisation.
Type 3
Are widely distributed over the Kalia deposit, with the most significant deposits occurring to the east of the Kalia I deposit and along the southern margin of the Kalia II deposit. Within the two areas over 20km2 of Detrital Iron Ore has been identified. The ores of this type are typical detrital iron formations that have been re-cemented with limonite and lesser extent vitreous goethite matrix. They are similar as the Massive Iron Oxide and Canga Ore types in that they have been cuirassed (cemented) on the surface and are very dense. The degree of cementation decreases with depth where the matrix becomes sandier.
Proximal to their source the ores contain debris of iron ore, quartz, amphibolites and sometimes greenschist. As the distance from source increases the percentage of gangue debris decreases.
Ore debris consists of haematite, goethite and magnetite. Limonite prevails in cement and is rarely found as debris. The cement matrix consists of sandy material with hydrous ferric oxides. The cementing matrix frequently becomes homogenous and dense because of new formation of hydrous ferric oxides. The thickness of ores of this type is extremely variable.
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