Unearthing Angola’s Treasures: Lucapa Diamond’s Exciting Kimberlite Exploration at Lulo Diamond Field

The Lulo Diamond Field in Angola has long been celebrated as a prolific source of some of the world’s most exceptional alluvial diamonds. Mining company Lucapa Diamond, in partnership with Empresa Nacional de Diamantes E.P. (Endiama) and Rosas & Petalas, has recently unveiled “exciting and highly encouraging” initial results from its ambitious exploration campaign to pinpoint the hard-rock kimberlite source(s) of these valuable gems. This significant advancement in the search for primary diamond deposits marks a pivotal moment for the Angolan diamond industry, underscoring the immense potential that lies beneath the surface of this famed region.

The strategic efforts undertaken by the Project Lulo partners have been unequivocally justified by the initial data, which strongly indicates the presence of diamond-bearing kimberlites. This exploration is not just about finding more diamonds; it’s about understanding the geological origins of these precious stones, which can lead to more sustainable and predictable mining operations in the long term.

The Lulo Legacy: A Field of Giants and Riches

The Lulo Diamond Field has already carved out a formidable reputation on the global stage, primarily for its incredible alluvial diamond recoveries. This region has consistently yielded diamonds of extraordinary size, clarity, and color, setting new benchmarks for value. Average run-of-mine sale prices from Lulo have consistently been around US$1,900 per carat, a figure that far surpasses industry averages and highlights the exceptional quality of diamonds found here.

Among the most remarkable discoveries from Lulo’s alluvial deposits are 14 diamonds weighing over 100 carats each. This impressive tally includes Angola’s largest recorded diamond, a breathtaking 404-carat stone that captured international headlines and further cemented Lulo’s status as a top-tier diamond province. The consistent recovery of such significant stones has naturally fueled the ongoing quest to locate their original host rocks – the kimberlite pipes from which they eroded millions of years ago.

Moreover, the Lulo field has produced Type IIa Specials, including stones up to 88 carats, four individual diamonds exceeding 50 carats, and highly sought-after fancy pink and yellow diamonds. These “Specials” are particularly valuable due to their exceptional purity and unique characteristics, contributing significantly to the high average per-carat prices. The consistent presence of these rare and valuable diamonds underscores the high potential of the kimberlite sources yet to be fully delineated.

Canguige Tributary: A Glimmer of the Source

A crucial breakthrough in this exploration phase came from stream bulk sampling conducted in the Canguige tributary. This waterway drains into the illustrious Cacuilo River valley, known globally for hosting some of the most valuable alluvial diamonds ever found. From this initial sampling, a total of 45 diamonds, with individual stones weighing up to 3.75 carats, were successfully recovered. This discovery is particularly significant because stream samples often provide direct clues about the presence of diamondiferous kimberlites upstream.

Preliminary analysis of these newly recovered diamonds, conducted using a Yehuda colorimeter, has already classified several of them as top D-colour. D-colour diamonds represent the highest grade of colorlessness, making them exceedingly rare and valuable. The presence of such high-quality stones in the Canguige samples strongly supports the hypothesis that a primary source of exceptional diamonds lies within this catchment area.

The sampling site in the Canguige tributary is strategically located approximately 3 kilometers from Mining Block 46. This proximity is vital as Mining Block 46 has historically been a significant producer of large and high-value diamonds, including Type IIa Specials, multiple +50 carat diamonds, and fancy coloured diamonds. The geological and spatial relationship between the Canguige findings and the established rich alluvial deposits suggests a strong connection to a proximal primary source.

Advanced Exploration Techniques Leading to Discovery

Lucapa Diamond’s latest kimberlite exploration phase is built upon a comprehensive and detailed technical review, meticulously integrating all previous exploration results. This extensive groundwork included advanced airborne geophysical surveys, which provide crucial insights into geological structures hidden beneath the surface, and an intensive kimberlite drilling and mineral chemistry program. These combined efforts have successfully identified over 100 kimberlites within the vast 3,000 km2 Lulo concession.

Out of these numerous kimberlite occurrences, 16 were rigorously prioritized for further investigation. This prioritization was based on a sophisticated evaluation of various factors, including their estimated size, precise geographical location, facies type (geological classification), and potential for dilution, among other critical parameters. Furthermore, an additional eight anomalies or kimberlite targets were identified, earmarked for targeted drilling to definitively confirm their status as true kimberlites and assess their diamond potential.

The current encouraging results stem specifically from the first stream bulk samples excavated from the Canguige tributary. These samples, totaling 1,865 cubic meters (m3), were carefully transported to the Lulo treatment plant for processing. Despite challenges, including narrow gravel seams and near-record rainfall that hampered excavation efforts and resulted in a “heavily-diluted” sample, the results were unequivocally positive. A total of 45 diamonds weighing 30.3 carats were recovered, including eight diamonds exceeding 1 carat and three diamonds over 2 carats, with the largest stone weighing 3.75 carats. Even with a calculated grade of 1.62 carats per 100m3 under challenging conditions, these recoveries are considered highly encouraging.

Confirming the Diamondiferous Source

These findings unequivocally confirm that the Canguige catchment area contains a diamondiferous kimberlite. This primary source is demonstrably contributing to the exceptionally high-value alluvial deposits found downstream along the Cacuilo River valley. This confirmation is a monumental step forward, transforming speculative targets into tangible evidence of a significant diamond discovery.

In response to these promising results, the Hanjin drilling rig has been promptly mobilized to the Canguige catchment area. It has already commenced delineation drilling of five specific kimberlite pipes that were highlighted as high-priority targets in the preceding technical review. The primary objective of this drilling campaign is multifaceted: to better define the precise geological structure and morphology of these kimberlite pipes, and crucially, to identify near-surface volcaniclastic kimberlite material. This material is particularly valuable for comprehensive bulk sampling to test for diamonds directly from the primary source rock.

Additionally, the two other high-priority targets identified during the extensive review phase will also undergo focused drilling. This targeted approach aims to confirm the definitive presence of kimberlite at these locations, systematically advancing the understanding of the Lulo concession’s underlying geology and diamond potential.

A Vision for the Future: Statements from Leadership

Stephen Wetherall, Lucapa Managing Director, articulated the historical significance of these developments, stating, “Across the history of diamond exploration, the recovery of diamonds and kimberlite indicator minerals from streams have been valuable pointers for the search of kimberlite pipes shedding those diamonds.” He further expressed the company’s enthusiasm: “We are excited about the diamond recoveries from the Canguige stream bulk sampling and look forward to advancing the next phase of our kimberlite search within the Canguige catchment.” This statement reflects a deep understanding of diamond exploration geology and a clear vision for the ongoing efforts.

The Lulo kimberlite exploration license, which operates separately from the Lulo alluvial mining operations, is held by the Project Lulo joint venture. Lucapa holds a 39% stake and acts as the operator, while Endiama maintains a majority 51% interest, and Rosas & Petalas holds 10%. This license encompasses the entire 3,000 km2 Lulo concession, granting the joint venture extensive rights to explore for primary diamond sources. While the current license is set to expire in April 2023, Lucapa has confirmed that it is actively engaged in discussions with the Angolan Ministry of Mineral Resources and Petroleum and Endiama. These discussions aim to potentially secure a majority stake in the Project Lulo joint venture, which would further solidify Lucapa’s commitment and strategic position in the long-term development of the Lulo Diamond Field.

Conclusion: A New Chapter for Angolan Diamonds

The initial results from Lucapa Diamond’s kimberlite exploration at the Lulo Diamond Field are not merely encouraging; they are a profound indicator of a potentially significant primary diamond discovery. The recovery of high-value diamonds, including top D-colour stones, from the Canguige tributary, coupled with the systematic application of advanced exploration techniques, is painting a clearer picture of Lulo’s geological wealth. As drilling continues and the kimberlite pipes are further delineated, the Angolan diamond industry stands on the precipice of a new era, one that promises sustained production of some of the world’s most exquisite diamonds directly from their ancient hard-rock sources. The ongoing collaboration and strategic vision of the Project Lulo partners are poised to unlock the full, long-term potential of this extraordinary diamond province, further cementing Angola’s role as a powerhouse in the global diamond market.

News Source: gjepc