Kroussou Project



The Kroussou Project is a large scale, near surface zinc-lead project with exploration to date validating province-scale base metals potential.


  • Globally significant initial Exploration Target defined at Kroussou;
  • Initial Exploration Target of between 140 and 300 million tonnes at a grade between 2.0% and 3.4% zinc plus lead has been defined from only six of the 23 Target Prospects;
  • Benchmarking of the initial Exploration Target for Kroussou demonstrates the Project has the scale potential to be a ‘Super Giant’ deposit;
  • Zinc and lead mineralisation is shallow across the target areas with an average depth of only 15 metres, which indicates potential for simple open pit mining extraction;
  • Excellent metallurgy confirmed, high recoveries and quality saleable zinc and lead concentrates;
  • High confidence in further discoveries across the province scale Project and strong potential for growth with further drilling;
  • Mining friendly jurisdiction, with Government support for expanding its mining industry;
  • Strong pipeline of news flow expected as Apollo takes next steps including expansion of exploration into the newly acquired Keri permit, ranking and drilling of high-priority targets and exploration of other Target Prospects.

The Kroussou project is located in south-west Gabon on the central west African coast. The project exploration permits, 100% owned by Apollo Minerals, is approximately 220km south of the capital Libreville within the Ngounié Province.

The Project consist of two exploration permits (G4-569 and G4-456) which cover 2,363km² and have 135km of strike length along the prospective contact between the Cretaceous Cotier Basin to the west and Archean/Proterozoic basement to the east.

Figure 1 – Kroussou Project highlighting 24 Prospects



The Kroussou Project is readily accessible using a bitumen highway that runs south from the capital Libreville and all-weather unsealed roads and logging tracks that lead into the project area (Figure 2). The project area is surrounded by significant oil and gas and logging activities which facilitates good access to the Kroussou Project area and useful road, port and communications infrastructure.

Gabon is a mature mining jurisdiction and as such, has a supply of labour that is used to support exploration and mining operations. Of late, there is a growing influx of Australian listed companies in the region.


Figure 2 – Location of Kroussou in Gabon with regional transport infrastructure

At the Kroussou Project, zinc-lead mineralisation is hosted in Cretaceous sediments on the margin of the Cotier Basin within preserved channels lying on unconformable Archaean and Paleoproterozoic basement rocks (Figure 3).

Exploration work carried out by previous operators identified 150 base metal occurrences along a +70km strike length of prospective geology within the project area. The zinc-lead mineral occurrences are hosted within exposed channels that offer very shallow, near surface targets close to the Archaean and Paleoproterozoic basement rocks. Only two of the 18 exposed channels were partially drill tested by the Bureau de Recherches Géologiques et Minières (BRGM) historically, with both channels containing significant base metal mineralisation.

As discussed below, a further two near surface targets were drilled by Trek Metals, which also returned significant zinc-lead intervals, further validating the province scale, base metal potential of the project area.

There are multiple opportunities for the discovery of further base metal mineralisation within the remaining untested 20 channels and also further exploration westward within the broader Cotier Basin is warranted with the expansion of area including the Keri permit.




Intermittent exploration was carried out on the Kroussou Project between 1962 and 1980, primarily by the BRGM, with latter work in partnership with the Gabonese Government organisation known as COMILOG. The BRGM carried out surface geochemistry comprising soil samples (on a grid of 50 x 50 metres), rock chip sampling (largely along the drainage network where exposures are most prominent) and minor stream sediment work, focusing largely on regional targets.

Some geophysics, including ground based induced polarization and electromagnetic programs, were completed in order to identify any potential near surface mineralisation. As a result of the compilation of the data received from this work, significant near-surface base metal mineralisation was identified where drilling was carried out. This drilling was limited to a small portion of the target area.

Approximately 400 very shallow holes (average depth of 16 metres) were drilled by the BRGM; of which most were either partially sampled, or totally unsampled.  The majority of the BRGM drilling was carried out on the Dikaki Prospect (Figure 1 & 3). Numerous shallow intersections of ore grade and width lead and zinc mineralisation were returned.

At the time, the BRGM were focused predominantly on the potential for lead and therefore did not fully explore the zinc potential which is today considered highly prospective.

The BRGM drill holes confirmed multiple horizons of flat lying mineralisation. Numerous intersections of massive sulphide were reported adding to the potential for significant zinc-lead mineralisation at the Kroussou Project.

Figure 3 – Kroussou Project Prospects Detailed



Trek undertook two small drilling programs in 2017 and 2018 at the Kroussou Project to confirm historical results, soil surveying, mapping, rock chip sampling and a ground geophysical program. To date, results received have indicated large anomalies corresponding with potential down-dip and along strike positions to known mineralisation within the Dikaki Prospect area.

Results from the 2018 drilling at the Kroussou Project included (see Trek’s ASX Releases dated 28 August 2018 and 10 December 2018):


  • 20.8 metres @ 4.2% Zn+Pb (DKDD010, from 2.4 metres)
  • 12.7 metres @ 4.6% Zn+Pb (DKDD012, from 25.1 metres)
  • 15.1 metres @ 6.1% Zn+Pb (DKDD013, from 0.7 metres)
  • 4.0 metres @ 15.2% Zn+Pb (DKDD029, from 8.1 metres)
  • 2.8 metres @ 6.0% Zn+Pb (DKDD028, from 8.9 metres)
  • 9.0 metres @ 4.5% Zn+Pb (DKDD033, from 37 metres)

Niambokamba (approximately 5km north of Dikaki):

  • 3.0 metres @ 4.8% Zn+Pb (NKDD001, from 45.0 metres)

This hole, NKDD001, was targeted at the southeastern end of a high order soil anomaly and is open.



Since entering the joint venture agreement with Trek Metals in 2020, Apollo has completed two drill programs, 2021 & 2022, and continued with the regional airborne geophysics, mapping and geochemical soil sampling across the Kroussou Project.

Regional mapping completed in 2021 and 2022 has targeted the southern areas including Salaganga North, Ofoubou, Yombi, Niamabimbou, Bouambo West and Niambokamba. Mapping has extended current known embayment systems with sulphide mineralisation mapped in outcrop at all areas. Rock chip sampling in the Salaganga North prospect returned grades of 2.12 and 5.18% Zn+Pb and 1.51% Zn+Pb at Ofoubou. These mineralised samples were taken from sandstone and siltstone outcrops with visible galena and sulphides.

Drill programs completed in 2021 and 2022 targeted prospects including Dikaki, Niamabimbou, Niambokamba and Ngongui, successfully discovering new areas of mineralisation, styles of mineralisation and expanding known mineralisation at Dikaki.

Significant drill intersections from the drilling include the following:


  • 10.3m @ 5.4% Zn+Pb from 18.0m (DKDD141)
  • 10.1m @ 5.7% Zn+Pb from 15.3m within 19.9m @ 4.0% Zn+Pb from 5.4m (DKDD121)
  • 13.5m @ 5.3% Zn+Pb from 12.8m within 32.0m @ 3.1% Zn+Pb from 4.0m (DKDD122)
  • 19.8m @ 4.0% Zn+Pb from 51.2m within 40.0m @ 3.1% Zn+Pb from 31.1m (DKDD118)

Niambokamba (approximately 5km north of Dikaki):

  • 3.5m @ 40.0% Zn+Pb from 3.5m within 6.0m @ 18.0% Zn+Pb from 1m (NKDD020)
  • 4.0m @ 8.6% Zn+Pb from 27.7m within 6.2m @ 5.91% Zn+Pb from 25.4m (NKDD029)
  • 4.4m @ 10.0% Zn+Pb from 37.4m within 8.7m @ 6.0% Zn+Pb from 36.4m (NKDD025)

Niamabimbou (approximately 5km north of Dikaki):

  • 5.3m @ 10.3% Zn+Pb from 54.7m within 27.1m @ 2.9% Zn+Pb from 1m (NBDD033)
  • 3.5m @ 4.6% Zn+Pb from 63.8m within 21.0m @ 2.0% Zn+Pb from 46.2m (NBDD031)
  • 5.7m @ 3.0% Zn+Pb from 27.4m within 19.9m @ 1.6% Zn+Pb from 13.5m (NBDD006)

Figure 4:  Dikaki section showing high grade results from drilling in 2022

Figure 5:  Figure 5: Niambokamba section showing high grade structure results from drilling in 2022

Figure 6:  Niamabimbou section showing passive seismic interpretation and drilling results



In 2022 Apollo completed 79 line kilometres of passive-seismic surveys and an extensive helicopter airborne electromagnetic (AEM) survey that covered the entire 80km strike of the Kroussou exploration permit. With line spacing of 200m over the main basin contact and 100m over the embayment prospects.

The AEM survey has been successful in identifying the embayment-style targets, identifying structural targets and is being used to further aid exploration in the Kroussou permit. Figure 7 shows the preliminary AEM results in the Niambokamba area with the recent drilling and a new embayment defined.

Figure 7:  Niambokamba prospect with new embayment identified by AEM survey with recent Apollo drill holes.



The current geological and mineralisation genetic model is summarised in Figure 8 as a hybrid Mississippi Valley Type (MVT) model whereby circulating fluids from the basin sediments and possible basement rocks leach metals via oxidised fluids and react with either reduced fluids from the surface water or organic matter within the sediment pile to drop out the mineralisation. Due to the structural architecture of the basin, structural control of mineralising fluids may be preferentially focussing base metal mineralisation into structural fault/breccia-controlled locations as noted at Niambokamba.

Figure 8:  Conceptual Mineralisation Model for Kroussou.



Apollo contracted Independent Metallurgical Operations (“‘IMO’) to conduct a metallurgical test work program and optimise the processing characteristics of the mineralisation discovered at Kroussou. The test work program was designed to define and quantify the characteristics of potential saleable concentrates from representative samples taken from Kroussou.

The mineralisation utilised for the test work was taken from diamond drill core from drilling conducted at Dikaki in 2021. The core was chosen to be representative of the known geology and to allow for determination of both the zinc and lead flotation characteristics. The master composite sample utilised for the test work was taken from four diamond drill holes with a head assay grade of 2.06% Zn, 2.61% Pb and 0.8ppm Ag (see ASX announcement 2 November 2022).

Test work conducted using an optimised flow sheet has demonstrated top-tier world-class recoveries with:

  • 93.0% zinc recovery of the contained metal into a saleable zinc concentrate; and
  • 94.4% lead recovery of the contained metal into a saleable lead concentrate.

The optimised processing flow sheet for Kroussou also delivered exceptional high-quality zinc and lead concentrates:

  • Zinc Concentrate Grade of 53.0% Zn; and
  • Lead Concentrate Grade of 70.0% Pb.

In November 2022, Apollo Minerals developed an initial Exploration Target this was estimated across only the six Target Prospects at Kroussou where modern diamond drilling has been completed, Figure 1. In addition to the modern drilling data, these six Target Prospects also have geological mapping, geochemical (soils) and geophysical (airborne electromagnetic (“AEM”), airborne magnetics and/or passive seismic) datasets to support the geological models. These combined data sets were used to create a geological and mineralisation concept model across the six Target Prospects and to define the initial Exploration Target (see ASX Announcement 9 November 2022).

The Initial Exploration Target for the six Target Prospects at Kroussou is summarised below in Table 1, displayed graphically in Figure 1 and consists of 140Mt to 300Mt at a grade between 2.0% and 3.4% Zn+Pb.¹


Exploration Target

Target Prospect

Min. Tonnage

Max. Tonnage

Min Grade
Zn+Pb (%)2

Max Grade
Zn+Pb (%)2

Metal Content
Mt (Zn+Pb)2

Metal Content
Mt (Zn+Pb)2

TP13 (Niambokamba)







TP11 (Dikaki)







TP10 (Bouambo East)







TP10 (Bouambo West)







TP8 (Ngongui)







TP6 (Niamabimbou)














2 Zinc is approximately 72% of the Zn+Pb total by mass. Note: Figures have been rounded which may affect totals.

Table 1 – Kroussou 2022 Exploration Target Summary.

¹The potential quantity and grade of the initial Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource. It is uncertain if further exploration will result in the estimation of a Mineral Resource. The Exploration Target has been prepared and reported in accordance with the 2012 edition of the JORC Code.


Figure 1 – Kroussou Project – Red colouring denotes areas of the initial Exploration Target.



The initial Exploration Target for Kroussou is detailed in the ASX announcement dated 9 November 2022, titled “Initial Exploration Target Kroussou Zinc Lead Project”.

The Exploration Target is based upon analysis of exploration data, including diamond drilling, geochemical analyses and geophysical surveys which have been undertaken over the project since 2017. Since 2017, there have been a total of 231 diamond holes drilled for 12,275m and 5,470 samples at Target Prospects 6, 8, 10, 11 and 13. Additionally, there were 447 diamond holes drilled for 7,865m from the 1960’s to the 1970’s undertaken by the Bureau de Recherches Géologiques et Minières (“BRGM”) of which only 164 holes have assays. As the BRGM holes were only sporadically sampled, only drilling undertaken by the Company (2021, 2022) and Trek Metals Limited (“Trek”) (2017, 2018) was utilised to inform the grade estimation. There has been extensive mapping of the basement contact over the entire permit length for G4-569, along with 12,000 soil geochemical samples, 270 stream samples and 653 rock chip samples taken. These combined data sets informed the areas selected for inclusion in the Exploration Target.

The process used to estimate the initial Exploration Target involved is summarised below and included the following main steps:

  • Embayment/paleochannel area limits were outlined and verified against available mapping, geophysics, sampling and drilling information;
  • A 3D evaluation of drill hole information utilising sectional interpretation was undertaken to assess geological and mineralised continuity of the data, while assessing the Zn+Pb% cut off grades of 1% and 2%;
  • Only drillholes drilled by the Company and Trek were utilised to determine grade ranges, whereas drillholes from BRGM were utilised to supplement continuity interpretation;
  • Maximum, minimum and average width and grade intersections were determined for each applied grade cut-off at each Target Prospect;
  • Volumes were determined based on weighted average mineralised widths for the applied cut-offs within the validated paleochannel area limits;
  • The applied cut-offs resulted in volume estimates from which tonnage ranges were determined utilising the weighted density measurements taken for each Target Prospect;
  • Based on the drillhole data density, the confidence in mapping, geophysical information, and qualitative geological risk, modifying factors were also applied to the raw tonnage estimates. The modifying factors applied ranged from a 35% to 60% discount applied to the tonnage ranges for each Target Prospect;
  • Maximum and minimum tonnage and grade ranges were determined utilising the results for the 1% and 2% Zn+Pb estimates post application of modifying factors; and
  • TP11 (Dikaki) which contains a significant proportion of information, underwent additional review and estimation using a more detailed 3D model and comparison to a separate outside estimate.

Exploration activities to test the Exploration Target include: Analysis of regional drilling and exploration completed at TP13 and TP8 in preparation for the 2023 field season; Additional surface exploration programs at additional Target Prospects comprising soil sampling, geological mapping, rock chip sampling to generate new targets; Drill targeting to test mineralised trends in the Target Prospects included in the defined Exploration Target. This work is envisaged to include infill and extensional drilling at TP11, and phase 2 drill testing at TP13 and TP6; Further drill testing of multiple targets across the Project area after ranking and prioritisation considering additional target.

The initial exploration program will focus on defining sufficient shallow (open-pittable), high grade zinc-lead mineralisation to justify commencement of feasibility studies.

The future work programs at Kroussou will aim to expand the broader exploration footprint, in addition to field work to test and further define the Company’s recently announced initial Exploration Target region. These activities are intended to include:

  • Ongoing analysis of regional exploration expanding from current known areas of mineralisation into under explored areas including both Kroussou and Keri permits;
  • Interpretation of regional AEM survey with a view to identify additional embayment and structural targets;
  • Continued field program with surface exploration programs comprising soil sampling, geological mapping, rock chip sampling to generate new targets and test high-grade structural trends;
  • Drill targeting and ranking of mineralised trends in the defined initial Exploration Target regions;
  • Drill testing of ranked targets across the broader Kroussou license package;
  • Follow up regional mapping and review of gold occurrences within the Keri permit at Salane including historical data review; and
  • Begin baseline social and environmental studies along side our ongoing community engagement initiatives.

The Company will undertake the work program with a strong commitment to all aspects of sustainable development and responsible mining, with an integrated approach to economic, social, environmental, health and safety management.