Mrima Hill

The Mrima hill rare earth and niobium property near Mombasa on the Kenyan coast is Pacific Wildcats flagship project in Kenya with the potential to become a world class resource. It is ideally located being close to essential infrastructure with sealed roads and mains power running adjacent to the deposit and the mineralised area is only 75kms by road from Mombasa the largest deep water port in East Africa.

This rare earth and niobium mineralisation at Mrima is related to a fault bounded basin of Jurassic age Karroo sediments intruded by Cretaceous aged alkali carbonatites with a thick mantle of enriched weathered rock as cover. The alkali intrusions at Mrima consists of carbonatite, agglomerate and fenitized sediments which have a surface extent of at least 2km by 1.3km being situated on the 1,180km2 special prospecting lease SPL256. The Mrima deposit comprises one of four alkaline intrusions that include the geographically separate hills of Mrima, Kiruku, Jombo and Nguluku which are probably joined at depth, intrusions which are associated with crustal rifting. These alkaline intrusives are all highly prospective for a range of minerals that include niobium, rare earths, gallium, tantalum, manganese and phosphate with both rare earth oxide (REO) and niobium having been outlined on the Mrima complex since systematic exploration by Anglo American and the Kenyan Mines Department commenced in 1952.

The carbonatite at Mrima is mineralogically classified as being either sovite or alvikite. Soil and laterite covers most of the Mrima hill and drilling by previous explorers has shown that the weathering profile is in places well over 100m deep. This depth of weathering has important implications for potentially high tonnage being present. The prolonged physical and chemical weathering of carbonatites at Mrima in these tropical environments on the coast of East Africa means the weathered zone (considerably less than 5% of the hill has outcrop) has been enriched and concentrated in both niobium and rare earth oxides. The niobium is believed to have been liberated from pyrochlore from the underlying fresh carbonatites (particularly the magnesian alvikite phase) and then to be concentrated into various secondary minerals and clays as a residual concentration through chemical weathering. The rare earth content has sourced mainly from bastnasite and monazite within the carbonatite and has been concentrated by both weathering processes and with an additional enrichment from a supergene process which may be analogous to what has occurred at the Mt Weld deposit in Western Australia. This enrichment process has produced both heavy and light REO with historical metallurgical work undertaken by the French company Pechiney Saint Gobain indicating that Mrima Hill may be well endowed with the more valuable heavy faction of rare earths.

Previous exploration started in earnest in the early to mid-1950s by both the Kenyan Mines and Geological Department and by Anglo American who extensively explored the cap of the hill. In particular Anglo American carried out an assessment of niobium mineralisation in the top of the weathered zone. Test pits were systematically dug over the hill top on a staggered 70m pattern with some four hundred 30 foot deep pits being dug plus a 305m adit excavated into the hillside together with eight up to 225m long diamond holes being drilled mainly for stratigraphical purposes. In 1957 Anglo analysed results from this test pitting and also from taking a 14 ton bulk sample where they estimated mineralisation of 50.5 million tonnes at 0.67 Nb2O5 including 5.3 million tonnes at 1.21% Nb2O5 This historic estimate from only the top 9.14m of the weathered profile is associated with weathering and leaching of the primary carbonatite which has been removed by weathering leaving a thick soil overburden. At the same time Anglo commenced its exploration activities in 1955 an estimate of 32 million tonnes at 3.1% REO was internally reported upon by the Mines and Geological Department of Kenya from the area they test pitted (at least 80 pits were used in the calculation) to a maximum of 8 metres. The next resource work was carried out in the period 1968-1971 when the French company Pechiney explored for europium but they were not interested in the other rare earths or the niobium potential and they quoted a 12,000 tonne europium trioxide mineralisation at 800ppm in one area sampled. In about 1998 the US Geological Survey re investigated the historical data and they estimated a higher grade area of REO and quoted 6 million tonnes at 5%. More recently on July 7, 2011 the company reported receipt of an NI 43-101 resource estimate report from ExplorMine Consultants of Johannesburg, South Africa that calculated a niobium resource in the inferred category of 105.3 million tonnes at a grade of 0.65% Nb2O5 for a contained total of 1,519 million pounds. The deposit is thought to contain a high grade zone of 10 to 15 million tonnes at 1.2-1.45% Nb2O5 based on a cut-off grade of 1.0% Nb2O5 using the historical shallow test pit data from the Anglo period of exploration. In total some 9,000m of test shafts 3,000m of drilling and 37 tons of bulk sampling has been undertaken by previous explorers at Mrima. Full details of the news release can be found at PAW NR #2011-14.

Note 1:
The rare earth estimates are not JORC or NI 43-101 compliant.  Test pitting requires twinning with modern assay techniques in at least 5-10% of the localities to give enough confidence on the previous sampling methodology so that it may possibly be fully incorporated in any new resource calculations and the company is not treating the historical estimate as a current mineral resource.

Pacific Wildcat plans to undertake modern drilling and sampling programs at Mrima Hill with both reverse circulation and diamond drilling to target primarily the known mineralised weathered zone, the base of which is not outlined, plus the company will also investigate the fresh rock potential at depth.  In October 2010 the company started this exploration phase with a 31 hole 974m RC drill program from accessible forest tracks over the hill top in the central part of the historically test pitted area. These results will eventually be used as the first stage of confirmation drilling for historical work. In subsequent drill programs work will be undertaken in the higher grade areas to fast track a resource for mining plus deeper diamond holes will also be drilled to better understand the depth potential of niobium and rare earth mineralisation.

In later drilling and soil sampling programs other commodities will also be targeted.  The potential of gallium within the tenements acquired has already been identified in encouraging amounts at the larger 3km diameter Jombo intrusive (comprising nephaline syenite foyaite and alkali pyroxenite) located some 6kms NW of Mrima. The Jombo intrusive plus the other smaller alkali intrusives in the vicinity of Mrima, all require systematic modern exploration including surface geochemical sampling to be completed. In addition base metals, phosphate, tantalum, gold and the platinoid potential of these complexes has also only been poorly tested in the past and requires thorough modern exploration techniques to be undertaken to see if these other minerals might prove to be present in economic concentrations.

View of Mrima Hill Carbonatite intrusion

Geological Map of Mrima (August 2010 American Mapping 1950’s)

Location of Kenya Mines Department test pits and Anglo American drill-holes sampled for Rare Earth

Location of Anglo American test pits and drill-holes sampled for Niobium