お知らせ • Aug 06
Prospect Resources Limited Announces the Results of the Recent Soil Sampling Program
Prospect Resources Ltd. announced the results of the recent soil sampling program and the exercise of the Meikle Option Agreement ("Agreement") at the Chishanya Carbonatite Project ("Chishanya"). The soil sample program has identified statistically elevated values and anomalies from the following
four oxides: Cerium Oxide (CeO2) 84 significant values (>615ppm), three of these anomalous (>2,455ppm). Lanthanum Oxide (La2O3) 10 significant values (>440ppm), two of these anomalous (>1,135ppm). Neodymium Oxide (Nd2O3) 36 significant values (>500ppm), three of these anomalous (>730ppm). Niobium Pentoxide (Nb2O5) 6 significant values (>430ppm), two of these anomalous (>1,430ppm). These results of moderate tenor from two well defined anomalies, in an area of limited surface outcrop, likely indicate the presence of sub-surface mineralisation and significant extra potential at depth. The average soil value of 775ppm represents a value almost five times greater than the crustal average of REE. Chishanya exhibits no signs of supergene concentration within a laterite that is often caused by tropical weathering. The considerable lithological variation seen at Chishanya is typical of carbonatites, and this leaves considerable scope for concentration of REEs at differing levels within the project. In short there is considerable potential for concentration on various REE combinations which have no current surface expression. The central Ce, La anomaly, with significant Nd and Pr, could represent the edge of a much larger multi- element deposit. There is also the potential for peripheral Nb (niobium) and of course the historically defined phosphate REE mineralisation tends to be concentrated in late carbonate phases such as ferro- carbonatites (ankerites) or coarse calcio-carbonatites (sÖvites) forming central breccia zones, ring dykes or cone sheets. They can also form distally to the carbonatite, along faults in the country rocks. By their nature carbonatites are geologically complex and require detailed investigations to understand their geology and mineralogical distribution. However, Chishanya certainly shows lithological affinities to other carbonatites worldwide that are host to significant REE and Nb deposits. Notable examples include Chilwa in Malawi and Mount Weld in Australia. The project, though undoubtedly primarily prospective for REE, also still has phosphate potential. Despite the metallurgical testwork by African Consolidated Resources (now named Vast Resources plc) indicating the difficulty in extracting the phosphate economically, this test work was limited in scope and the grades do compare favourably with the Dorowa mine, located 100km to the north. At Dorowa, the Industrial Development Corporation are currently mining rock phosphate at 6.5% to 8% P2O5, from a similar carbonatite. The Chishanya carbonatite lies in the Buhera district in the south-east of the country (Figure 1), 25km north of Birchenough Bridge (19° 45'S; 32° 18'E). It is a lower Cretaceous age carbonatite complex with an approximate width of 1.5 km and a length of 5 km north-northeast to south-southwest. The carbonatites (mainly coarse calcium rich sÖvites) form arcuate dyke like bodies intruded by alternating layers of ijolite, fenite and foyaite. Thin layers and stringers of magnetite and apatite occur within the sÖvites, in parts these reach 2- 3 m width. The surrounding hills contain lenses of late-stage dark brown Fe-carbonatite, rich in magnetite and apatite. Outcrop is limited, though valleys and flanks of the hills are covered by soil of variable thickness. Most previous work has been concentrated on near surface exploration, with only two boreholes ever having been drilled into the main Chishanya hill (Industrial Development Corporation 1968). Intersections of 11.73% and 2.31% P2O5 were obtained from depths of 304m and 342m respectively. It should be noted that these holes were drilled primarily to test (unsuccessfully) for Palabora style copper mineralisation. X November 2018 values of up to 15% P2O5 from historical surface trenching undertaken by the Chishanya has returned Meikles family. Subsequently, selective mining of the 2-3 m wide apatite-rich dykes at Baradanga Hill has been considered (Barber 1991). This area was estimated to contain 1,600 tonnes of ore per metre depth with an average grade of 8% P2O5. African Consolidated Resources (ACR), now Vast Resources plc, undertook an assessment of the phosphate potential of the area in 2013. This was primarily a soil sampling exercise, with assaying done by hand held XRF. As part of their study, ACR did however also drill two bore holes into the northern Baradanga Hill, with one of the holes intersecting P bearing carbonatite. This hole was also assayed for a limited number of the REEs (Y, Tb) and Nb and returned a peak value of 2,000ppm. Apart from this one borehole, no other exploration for REEs, uranium, yttrium and niobium has ever been undertaken on this project. 1,075 soil samples were collected initially at 20m intervals along north-south lines (Figure 2), spaced at 100m. The subsequent results indicated that Chishanya Hill and Baradanga Ridge were anomalous, and it was decided to increase the sample density to be on 50m spaced lines in these specific areas. Ultimately a total of 1,275 samples were collected and pulverized to 75u, prior to being dispatched to SGS for REE and selected base metal analysis. 1,275 plus QA/QC samples were assayed for REE and associated base metals (including niobium and scandium) at SGS Randfontein. Two distinct total rare earth (TREE) anomalies have subsequently been identified at Chishanya Hill and Baradanga Ridge, covering 0.2 and 0.1 sq kms respectively. 213 of the samples from these areas are statistically elevated and therefore considered significant, outlined in Table 1 (> 1,170ppm TREOs and eight of these anomalous (> 2,330ppm). Twenty percent of the TREO values are attributable to Nd2O3 and Pr6O11.
