Mineralogical testwork of soil samples taken from rare earths miner Pensana’s Angola-based Sulima West exploration licences reveal the deposit contains monazite, which hosts neodymium and praseodymium that require moderate liberation and exposure, thereby making the mineralisation amenable to some degree of simple upgrading at the current location, prior to processing at Longonjo, where the company is building its Longonjo mine.

The three samples were analysed by South African inspection, testing, verification and certification company SGS South Africa.

Electron microprobe work was required to determine the mineral chemistry of the rare-earth element- (REE-) bearing minerals, particularly the element present at low concentration, which was required for the REE deportment and was incorporated into tescan integrated mineral analysis data.

All the targets occur within the Coola exploration licence, located about 40 km north of Longonjo.

“The opportunity for upgrading the ore at the current location using physical separation techniques will be further assessed with the testing of larger samples which are in the process of being collected,” comments Pensana exploration manager Grant Hayward.

He explains that both the Sulima West and Coola targets have the potential for the upgrading of the ore at their current location, thereby providing a high-grade near-term feedstock 40 km from Longonjo.

The Coola exploration project – comprising three highly prospective targets: the Sulima West carbonatite, the Coola carbonatite and the Benga Novo alkaline complex – is located about 160 km east of Angola’s Port of Lobito, covering an area of 7 456 km2.

Pensana, through 90%-owned subsidiary Coola Mining, was granted the Coola exploration licence in May 2020 and conducted multiple programmes from 2020 to 2022.

Rock chip sampling of the 0.9-km-diameter Coola carbonatite ring dyke returned values of between 0.6% and 4.9% total rare-earth oxide, averaging at 2.6%.

Mineralogical studies of the Coola carbonatite identified the REE 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 fluoride.

Economic grades of REE mineralisation in the form of bastnaesite has been located in banded dolomitic carbonatites at the Coola carbonatite.

The Sulima West target is a 4.2-km-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.

Twenty-two initial reconnaissance samples were extracted from the trenches in 2021, during which it was observed that the trenches were excavated into an iron/manganese-rich laterite similar in appearance to the REE laterite developed over the Longonjo carbonatite.

Pensana reports that the results of this initial sampling returned significant values for rare earth oxides with up to 10.6% total rare-earth oxide encountered in the laterite and averaging 4.2%. Manganese oxide values of up to 15.9% and averaging 7.2% were also reported.