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Gécamines and its predecessors explored the deposits within the Kalukundi and surrounding areas between 1927 and 1987. The work consisted mainly of extensive pitting (up to 16m), trenching, mapping and sampling. The pitting data was extensively used for creating geological maps in areas with almost no outcrop. Virtually all of these pits are still open and can be located in the field.
Mapping and presentation of geological data by Gécamines was performed to a high standard and Geo-Consult and Africo Geologists have made some changes to the original Gécamines and Geo Consult maps based on new data secured from the drilling and from more detailed surface mapping and trench data.
Trenching is the only way of penetrating the thick soil and ferricrete cover to search for the geology and mineralisation. Once minerlisation has been found, close spaced trenching follows the mineral-rich units to define the areas on which drilling activity can be focussed.
World class Copper/Cobalt mineralisation in the DRC Copperbelt is hosted by sedimentary rocks of the 7000m thick Neo-Proterozoic Katangan Sequence developed within the Lufilian Arc. This Copperbelt is 600km long extending from Luanshya (Zambia) in the south-east to Kolwezi in the Democratic Republic of the Congo (DRC) in the north-west.
In the DRC, the Katangan Supergroup is preserved both as tightly folded, but relatively intact sequences and as complexly deformed, locally continuous but structurally dismembered 'rafts' of lower Roan strata (Series Des Mines) within a 'mega breccia' or melange that contains abundant evaporite minerals. The main geological unit making up the ore horizons in the Roan strata are listed as follows:
Of the 12 fragments and 2 or 3 smaller rafts identified in the Kalukundi concession area, only 4 have been drilled in detail and resources and reserves calculated. These are the Principal. Anticline, Kalukundi and Kii Fragments. The dimensions of the 4 fragments evaluated in detail during the Feasibility study and the depth of oxidation is listed as follows (strike length & drilled width; vertical depth of oxidation):-
The deepest drill hole intersects mineralisation at 490 m below the surface. From this it can be seen that there is significant potential to locate additional ore resources in depth.
Preliminary exploration and evaluation work has been undertaken on the other fragments and 3 of these namely Kesho and Kinshasa fragments and the smaller Golf raft have been found to contain well developed copper and also significant cobalt mineralisation, identified in outcrops, trenches and larger excavations. One vertical borehole on Kesho by Gécamines intersected the ore-bearing stratigraphy and returned some excellent cobalt values.
These 3 fragments (& possibly other fragments) represent significant upside ore potential to the existing Kalukundi resources.
During this year, efforts have been focused on the mapping and surface sampling of the Kesho, Kinshasa and Golf fragments, preparatory to a definitive exploration drilling programme. A program of 6000m of core drilling due to commence at the end of the rainy season in March 2007 will search for ore grade ore resources on the various fragments, but commencing with the above name 3. Based on the results of this drilling, additional ore definition drilling would be proposed.
The fragments are folded, forming tight, steeply dipping synclinal and anticlinal structures. The vergence of the folds is variable on a regional scale; this is consistent with the interpretation of chaotic fragments within a mega-breccia. The dip of the limbs at Kalukundi is mainly steep from vertical to 85°, but also shallow down to 45°. In place very shallow to subhorizontal dips are found to occur.
Individual fragments are terminated by faults on their lateral extents, and crosscutting brittle faults offset stratigraphy, especially in the Principal fragment. Fault displacements vary between 15m (Principal) and 45m (Kalukundi). These shears and faults may have provided passageways for siliceous fluids and fluids responsible for the hypogene alteration process and the remobilisation of copper and cobalt.
All the mineralised zones have been faulted and/or folded to varying degrees of intensity, but gross continuity of the lithological units can nevertheless be demonstrated.
Post depositional hypogene processes have strongly affected these deposits. These processes have resulted in solution and removal of much of the carbonate minerals and selective replacement by silica. This process is best reflected in the central RSC unit where the solution process has left numerous vugs and the silica replacement is widespread making this formation highly resistant to surface weathering. The leaching and associated weathering processes have resulted in oxidation of the primary copper and cobalt sulphides in the surfical environment. The depth of oxidation varies considerably from fragment to fragment, from 40m on Kalukundi to 120m on Principal (Insert section 10 from the Principal). In addition, partial oxidation has been observed at a vertical depth of 270m in an intersection on the Principal fragment. These processes are also responsible for remobilisation of the copper and cobalt oxides. Much of this occurs locally within the host unit, such as the SDB, (Upper ore body) and the D Strat and RAT Grise (Lower ore body). However, significant oxide copper and cobalt now occurs within the central RSC unit. Hence the RSC now forms a major part of the ore sequence.
The principal copper bearing minerals in the sulphide zone are chalcocite, chalcopyrite and bornite. Cobalt is present as carrollite. Within the oxidised zone, copper occurs essentially as malachite and with lesser cobaltiferous malachite with subordinate kolwezite and chrysocolla. Cobalt occurs essentially as heterogenite. Sphaerocobaltite occurs within the RSC in the supergene zone in very small amounts.
Within the Kalukundi fragment, significant amounts of chalcocite are developed beneath the depth of 40 m below surface in a supergene zone. This supergene mineralisation can be anticipated in the interface between oxides and sulphides at deeper levels on the other fragments also.
Heterogenite appears to be enriched near surface, especially in the subsurface from 4m down to about 40m depth.
This information has been prepared under the supervision of Mike Evans, Africo's consulting geologist who is a qualified person under National Instrument 43-101. For further details refer to the Technical Report dated June 2006 filed on SEDAR at www.sedar.com.
