Loncor's Transformation has begun

Moving up the value curve

in the DRC's goldfields

The Imbo Project holds significant resources and numerous early stage prospects


The Company acquired control of the Imbo project, as well as a number of other gold exploitation concessions, in the east of the Ngayu greenstone belt in the DRC in September 2019.  The Company initially acquired a 71.25% interest in these projects, which subsequently increased to 84.68% in September 2020.  The Imbo project contains numerous targets of interest including the three resource bearing deposits of Adumbi, Kitenge and Manzako, the deposits occurring within a 5-kilometre radius of each other. Loncor is fully financed to drill at least 12 holes at Adumbi as part of a plan to increase the resource significantly.

Historically the Imbo area was mined on a relatively small scale in the 1930s by Belgian operators, with the majority of output originating from our main target, Adumbi.

Figure 1: Location of Imbo Project Area in Ngayu Belt

After assessing exploration results undertaken between 2014 to 2018, including re-logging of all previous boreholes and undertaking additional drilling at depth, Loncor announced on April 17, 2020 the gold content of the inferred resource of the three deposits had increased by 49% to 2.503M ounces (30.65 million tonnes @ 2.54 g/t Au), compared to the previous resource determination undertaken in 2014. Loncor has an attributable interest of 84.68% in this resource. On June 10, 2020, a NI 43-101 technical report on the Imbo Project was filed on SEDAR and confirmed the inferred resource increase at the Imbo Project, having been prepared by Minecon Resources and Services Limited with an effective date of April 17, 2020. A copy of the said report can be obtained from SEDAR at www.sedar.com. Further detail on the resource upgrade can be found in the Resource section of this website, and Loncor’s news release of April 17, 2020 and June 10, 20200.

Loncor will look to add to the resource ounces through a focussed 12 hole, +7,000 metre drill program this year. Further drilling may also occur at Kitenge and Manzako. The initial aim of the program will be to add to the Adumbi resource base both within the US$1,500/oz pit shell, and in areas below the pit shell.  Southeast of Adumbi there is ongoing exploration at Imbo East including gridding, soil sampling, trenching and channel sampling in order to generate potential drill targets.

Figure 2: Deposits and emerging areas of interest within the Imbo Project Area


The Ngayu Archean Greenstone Belt of northeastern DRC is geologically similar to the belts which host the world-class gold mines of AngloGold Ashanti/Barrick’s Kibali mine in the DRC (Moto greenstone belt) and AngloGold Ashanti’s Geita mine in Tanzania (Geita greenstone belt).  Gold mineralization at Ngayu is spatially related to Banded Ironstone Formation (“BIF”), which is the case at both Kibali and Geita.  The Ngayu belt is significantly larger in extent than the Geita belt.   

Based on initial studies in 2017 by Barrick which has a joint venture with Loncor on almost 2,000 square kilometres within the Ngayu belt, it was found that a major structural, mineralised fracture zone separates an older volcano-sedimentary domain in the northern part of the Ngayu belt from a younger, predominantly sedimentary basin in the south.  At Barrick’s Kibali mine, a similar geological setting has been determined with the gold deposits spatially related to a major structural break between an older volcano-sedimentary domain and a younger predominantly sedimentary basin.  

At Ngayu, the major structural fracture trends east-northeast through the Imva area where a number of targets are located and then trends southeast through the Imbo mining licence where the Adumbi, Kitenge and Manzako deposits are located and then across the Imbo river to the Imbo East prospect.  In total, this major structural break extends for 16 kilometres within the Imbo licence and will require further exploration to fully evaluate this prospective trend.  Recent reconnaissance to the east of the Imbo river at the Imbo East prospect has substantiated the potential of this structural trend with several artisanal workings being located over four kilometres of strike. Mineralization is found within steeply dipping metasediments with or without quartz veins. These metasediments are found immediately southwest of a prominent range of BIF.  A detailed soil sampling, geological mapping and systematic channel sampling program is being undertaken on the entire Imbo East mineralized trend which will be aided by the recently completed LIDAR survey over the Imbo licence.

Key Elements of the April 17, 2020 Mineral Resource Upgrade At Adumbi - (Detail available in the NI 43-101 Technical Report Filed on June 10, 2020)

Since September 2019, Loncor has been focussing on the Adumbi deposit, where Minecon Resources and Services Limited ("Minecon"), the Company’s independent geological consultants, reviewed exploration undertaken during the period 2014 to 2018. The updated resource estimate for Adumbi was based on incorporating additional drilling, relogging of all boreholes drilled prior to 2014, resurveying and sampling old adits and incorporating additional relative density measurements. The Adumbi deposit was remodelled considering the CIM requirement for mineral resources to have “reasonable prospects for economic extraction”. On June 10, 2020, a 43-101 technical report on the Imbo Project was filed on SEDAR, having been prepared by Minecon with an effective date of April 17, 2020.

In summary for the Imbo Project, the inferred mineral resource for the Adumbi, Manzako and Kitenge deposits increased by 49% from the previous resource determination undertaken in 2014 and now totals 2,503,000 ounces of gold (30,650,000 tonnes grading 2.54 g/t Au) and is summarised in Table I below. All of the resource increase was attributed to Adumbi, with no change in the figures for Kitenge and Manzako, the two satellite deposits that sit within a 5-kilometre radius of Adumbi.  84.68% of this inferred mineral resource is attributable to Loncor via its 84.68% interest in the Imbo Project.

Table 1: Inferred Mineral Resource for the Imbo Project (with an effective date of April 17, 2020)





(g/t Au)

Contained Gold


















Note: Numbers may not add up due to rounding.

More detail on the resource upgrade can be found in the Loncor Press Release dated April 17, 2020, however here follows a summary of the key elements of the work undertaken during the period 2014-18 which Minecon incorporated into the updated mineral resource determination:   

Re-logging of All Drill Holes

All boreholes (153 holes totalling 33,651 metres) from Adumbi were systematically re-logged and all data was put on (Strata Logs software) including core orientations.  The re-logging of drill holes has defined the presence of various key geological domains across the Adumbi deposit. As an example five distinct geological domains in the central part of the Adumbi deposit where defined, where the BIF (Banded Iron Formation) unit attains a thickness of up to 130 metres. In the central part of the Adumbi deposit, three main zones of gold mineralization appear present. There is a higher-grade zone of gold mineralization termed the Replaced Rock Zone (“RP Zone”) associated with alteration and structural deformation that has completely destroyed the primary host lithological fabric. 

Figure 3: Overview of the pit shell and geology of the central section of Adumbi Deposit

Figure 4: Cross-section across the central part of Adumbi Deposit

Relative Density (“RD”) Measurements

The increase in the sample population coupled with the application of a more rigid RD determination procedure based on recommendations from the previous independent consultants' study by Roscoe Postle Associates Inc (RPA) in 2014, indicated that the new RD measurements from both mineralized and unmineralized material and from the various material types and lithologic units have improved the confidence in the relative RD determinations to be applied to any resource estimates. Table 2 details the findings.

Table 2: Summary of Previous and Updated Mineralised Average RD Measurements for Adumbi Deposit

Material Type

RD used in Previous RPA Model

RD Determinations Used in Current Model

RD Variance















Gold Price

A gold price of US$1,200/oz was used in 2014 for the RPA study. To reflect more recent market conditions, a gold price of US$1,500/oz ounce was used by Minecon to determine the depth extent of the calculated inferred resources. 

Figure 5: Illustration of 3D mineralization model and comparison of pit shells assumed.

Pit Optimisation Parameters Used in the NI 43-101 Technical Report - Imbo Resource Upgrade

To constrain the depth extent of the geological model and any mineral resources, an open pit for the Adumbi deposit was constructed based on the following pit optimisation parameters:

  • A long-term gold price of US$1,500/oz.
  • Block size: 8 metres x 8 metres x 8 metres.
  • A two-metre minimum mining width and a maximum of four metres of internal waste was applied.
  • Mining dilution of 100% of the tonnes at 95% of the grade.
  • Ultimate slope angle of minus 45 degrees.
  • Metallurgical recoveries of 95% for oxide and transitional material and 90% for fresh rock (in the RPA study a fresh rock metallurgical recovery of 95% was used while Minecon reduced this to a more conservative 90% even though no additional metallurgical test work was undertaken after the RPA study).
  • Average mining cost of US$2.5/t mined.
  • Mineral resources were estimated at a block cut-off grade of 0.9 g/t Au constrained by a Whittle pit with processing and G&A costs of US$30/t.
  • Transport of gold and refining costs equivalent to 4.5% of the gold price.
  • No additional studies on depletion by artisanal activity was undertaken since the 2014 RPA study and the same total amount of material was used by Minecon.

The results of the Adumbi pit optimisation indicated an inferred mineral resource within the pit of 2.19 million ounces of gold (28.97 million tonnes at 2.35 g/t gold Au).

Table 3: Split of Material Type of Adumbi Mineral Resource (with an effective date of April 17, 2020)

Material Type




(g/t Au)

Contained Gold


















Note: Numbers may not add up due to rounding.

The additional drilling information, the higher RD determinations and the increased gold price, have contributed significantly to the increased mineral resources of the Adumbi deposit with improved confidence.

Additional Resource Potential and Recommendations for Further Work

There is significant additional resource potential within the Imbo project:

  • At the Adumbi deposit, the gold mineralization is still open at depth and the drilling in 2020 of an additional 12 core holes (+7,000 metres) has the potential to add and upgrade mineral resources within the US$1,500 pit as well as outline potential underground resources below the pit (see Figure 6).  After this drilling program has been completed, additional drilling may be undertaken (subject to securing the necessary financing) before a Preliminary Economic Assessment is initiated to include additional mineral resource determinations, metallurgical test work, open pit and potential underground studies, metallurgical plant processing, infrastructural, environmental and economic studies.
  • At the Kitenge and Manzako deposits, additional drilling may also be undertaken to further define and increase the inferred mineral resources at these deposits. 

Ongoing exploration including gridding, soil sampling, trenching and channel sampling is planned to be undertaken at the Imbo East prospect in order to generate potential drill targets. In June 2020, two new targets were announced. Both these target areas were identified from the compilation and interpretation of previous, historical exploration data including soil geochemistry, rock chip and channel sampling. At Mambo Bado, 1.5 kilometres northwest of the Adumbi deposit, a prominent geochemical gold in soil anomaly is located on an extensional, E-W structural jog along the 14-kilometre northwest trending mineralised shear zone within the Imbo permit area. No drilling has been undertaken previously on this promising target. Two kilometres south of the Adumbi deposit, at Lisala, altered and brecciated BIF with anomalous rock sampling requires further follow up with gridding, soil sampling and additional channel sampling.

Figure 6: Adumbi Longitudinal Section showing Proposed Drill Holes

Qualified Person

Peter N. Cowley, who is President of Loncor and a "qualified person" as such term is defined in National Instrument 43-101, has reviewed and approved the technical information on this web site.

Technical Report

Certain additional information with respect to the Imbo Project is contained in the technical report of Roscoe Postle Associates Inc. dated February 28, 2014 and entitled "Technical Report on the Somituri Project Imbo Licence, Democratic Republic of the Congo" plus the more recent Minecon Resources and Services Limited NI 43- 101 Technical Report on the Imbo Project filed on June 10, 2020. A copy of the said reports, can be obtained from SEDAR at www.sedar.com






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