Pensana plc (LON:PRE) has reported on analytical results received from sampling at the Sulima West and Benge Novo targets completed in 2022. Both targets occur within the Coola Exploration License (No059/02/01/T.P/ANG-MIREMPET/2020) located 40 kilometres north of Longonjo. Results recently received include:
- analytical results from the soil sampling programme conducted over the Sulima West carbonatite rare earth element (REE) target in October of last year;
- whole rock geochemistry and analytical results for the significant apatite-maghemite-monazite outcrop at Sulima West; and
- XRD, whole rock geochemistry and analytical results of Benge Novo alkaline complex deeply weathered clays for bauxite and ionic clay potential.
Sampling highlights include:
- soil sampling at Sulima West clearly identifies an area of approximately 500 x 300 m (~15 hectares) with > 2% TREO in soils with a core zone of high-grade soils reporting >4% TREO;
- whole rock geochemistry results from the apatite-maghemite-monazite sample returned 22% P2O5, 26.8% CaO, 40.5% Fe2O3 and 0.7% TREO; and
- clays at Benge Novo returned grades of up to 1600 ppm TREO.
Exploration activities are scheduled to continue throughout 2023 with geophysical surveys (magnetics/radiometrics/gravity) commissioned for Q3 2023, and further mapping, trenching, sampling and mineralogical studies scheduled for the remainder of the year.
Exploration Manager, Grant Hayward, commented:
“We are extremely happy with the results of the soil sampling over Sulima West which identified an area of roughly 15 hectares with greater than 2% TREO in soils. The soil anomaly includes the Trench 1 where very encouraging REE results were sampled (14 Nov 2022: Exploration Results from Coola Exploration License).
It is suspected that the REE enriched regolith represents the near surface expression of a deeply weathered supergene enriched carbonatite as is the case at Longonjo. In addition, high grade, regolith hosted, residual apatite has been identified at Sulima West with grab samples of over 20% P2O5 reported.
Ground geophysical surveys including magnetics/radiometrics and gravity commenced in August 2023 with resulting data to be utilised for further target generation. Further trench and pit sampling of the soil anomaly and prospective geophysical targets will take place later in the year once the geophysical data has been processed and interpreted.”
Sulima West Soil Sampling
Two hundred and thirty-eight soil samples were collected on a 50 m x 50 m sample spacing over an area of 650 m x 800 m covering the area of identified historic trenches and surroundings at the Sulima West target. Individual soil samples are from 10-20 cm below surface, were sieved to <0.5 mm, bagged and dispatched for ICP-MS analysis at IGEO Laboratories, Luanda. QA/QC samples were submitted, and the laboratory results were within acceptable limits.
The soil sampling clearly identifies an area of approximately 500 m x 300 m (~15 hectares) with >2% TREO in soils within which a zone with >3% TREO is delineated.
Figure 1: Sulima West REE target – TREO% in soils with grade contours
Five of the historic trenches excavated during the 1970’s are included within the >2% TREO soil anomaly. Due to safety issues such as possible wall collapse only the southernmost trench (Trench 1) has been logged and sampled to date. Trench 1 comprises 68 m of iron/manganese enriched lateritised regolith and was sampled at 2 m intervals returning values of between 0.3 and 9.7% TREO, with an average of 3.4% TREO over 68 meters reported. Pit 1, which occurs within the >4% TREO in soil anomaly, returned 4.3% TREO over a vertical distance of 6 metres.
The remaining 4 historic trenches within the anomaly will be cleaned and made safe and will be sampled during late 2023. A large portion of the >4% TREO in soil anomaly occurs to the SE of the historic trenches and this area will be trenched and sampled during 2023.
A representative sample of the 800 m2 outcropping secondary, supergene apatite-maghemite-monazite regolith has been submitted for Mineral Liberation Analysis at SGS laboratories, South Africa. This work is currently in progress.
Initial whole rock geochemistry results received from SGS returned 26.8% CaO, 40.5% Fe2O3, 22% P2O5, 2.4% TiO2 and 0.7% TREO. These results indicate that approximately 50% of the rock is apatite. Further work is being done to delineate the extent of this rock type the area having the potential to host a significant phosphate resource.
Benge Novo Clay Sampling
Whole rock geochemistry and analytical results of clays collected from the deeply weathered Benge Novo alkaline complex were received. Clays were collected to determine possible bauxite and ionic clay potential. The clays showed a low Al2O3 content (<18%) with no bauxite minerals identified, however, the clays typically contain up to 1600 ppm TREO. The REE distribution shows a typical LREE distribution.
XRF reports 65% SiO2, 18% Al2O3, 4.4% K2O and 3.5% Fe2O3. XRD work reported 46% quartz, 23% microcline, 26% kaolinite and 5% phlogopite.
The Benge Novo complex is vast (10 km minimum in diameter) and soil covered. Further mapping, sampling and geophysics is required to effectively assess and explore this prospective alkaline complex.
About the Coola Exploration Project
The Coola Exploration Project located in Angola, approximately 160 km east of Port of Lobito covers an area of 7,456 square kilometres. The Coola Exploration Project consists of three highly prospective targets namely the Sulima West carbonatite, the Benga Novo alkaline complex and the Coola carbonatite. The three highly prospective targets are located between 40 and 100 kilometres north of Pensana’s Longonjo project.
Pensana, through Coola Mining LDA in which Pensana holds a ninety percent interest, was granted the Coola exploration license in May 2020 and has since completed multiple field programmes in 2020, 2021 and 2022 involving geological mapping, rock chip sampling, trench and pit sampling, stream sediment sampling, initial radiometric surveys, close space soil sampling and assaying confirming rare earth mineralisation across all three carbonatites/alkaline complexes.
Sulima West is a 4.2-kilometre diameter alkaline carbonatite ring complex with a corresponding high radiometric
response occurring immediately to the south of the Benga Novo intrusion and to the west of the Sulima ring structure. 10 historic trenches each of about 90 metres in length located in the western segment of the structure were identified and corresponded with the highest radiometric response. Twenty-two initial reconnaissance samples were extracted from the trenches in 2021. During this sampling, it was observed that the trenches were excavated into an iron/manganese-rich laterite very similar in appearance to the rare earth element laterite developed over the Longonjo carbonatite. Results of this initial sampling returned significant values for rare earth oxides with up to 10.6% TREO encountered in the laterite and averaging 4.2% TREO. Manganese oxide values of up 15.9% MnO and averaging 7.2% MnO were also reported. In Q2 2022, further trench and pit exploration activities were conducted at the Sulima West target, reporting initial rare earth grades of up to 9.7% TREO averaging 3.4% TREO over 68 metres at surface in the trench and up to 5.2% TREO, averaging 4.3% TREO over 6 metres at surface for the pit. The presence of highly anomalous TREO of >10%, the anomalous radioactivity, outcropping fenite, as well as significant manganese and supergene apatite, are all supportive of a carbonatite at depth.
The Benga Novo intrusion is interpreted as a very large caldera occurring immediately to the north of the Sulima West intrusion. It is regarded to be at least 8 to 10 kilometres across and is characterised by flat, deeply weathered soils with a solitary alkaline granite outcropping in the south eastern part. The identification of a significant, clay dominated, deeply weathered regolith over parts of the main Benga Novo intrusion may additionally be prospective for the occurrence of ionic clay hosted REE deposits. The Benga Novo intrusion is believed to be vast (approaching 100 km2) and the potential for alkaline silicate related mineralisation such as REE, Nb, U and Zr is deemed positive.
The Coola carbonatite is a roughly circular body, measuring about 900 metres across as inferred from the limited outcrops of carbonatite and fenite. The circular shape suggests that the Coola carbonatite may be a ring dyke or breccia pipe, similar to the carbonatite at Longonjo. Rock chip sampling of the 0.9 km diameter Coola carbonatite ring dyke returned values of between 0.6% and 4.9% TREO (average 2.6%). Soil geochemistry over the covered carbonatite returned values of between 0.37% and 13.18% TREO (average 3.21%). Mineralogical studies of the Coola carbonatite identified the rare earth mineral to be bastnäsite, which occurs as discrete veins, veinlets, and segregations within the carbonatite. Soil geochemistry over the fluorite-rich zone at Coola identified an area of 13 000 m2 with average fluorite values of 17% (Calcium Flouride) CaF2. Economic grades of REE mineralisation in the form of bastnaesite has been located in banded dolomitic carbonatites at the Coola carbonatite.
The Angolan government has implemented a modern mining code with an attractive fiscal regime and a range of investment incentives including tax exemptions and customs duty exemptions. Over the past decade it has also made significant investments in business-critical infrastructure such as railways, ports, bridges, and roads.
The Lobito Corridor railway, the historic 1739 km umbilical cord to the strategic minerals mined in the Copperbelt straddling the DRC and Zambia, is now under concession management by the Trafigura/Mota-Engil led Lobito Atlantic Corridor consortium. Alongside the management of Lobito Port, it is the latest under the roll-out of government privatisation initiatives. Angola currently enjoys a power supply surplus following mega hydro-electric projects and expansion of the national grid.
Angola’s economic profile has improved significantly over recent years, with the country’s public debt falling from 131% of gross domestic product in 2020 to 66% in 2022. The IMF has projected that the economy will grow by 3.5% in 2023.
Following an upgrade by Moody’s in late 2021, all three major rating agencies raised their credit assessment of the country’s sovereign debt in 2022, with Fitch and Moody’s upgrading the country outlook from neutral to stable in the second half of the year.