NEWS..ADUMBI Increases by 1 M ounces..total 4.7 M ounces 2021-04-27 07:30 ET - News Release
TORONTO, April 27, 2021 (GLOBE NEWSWIRE) -- Loncor Resources Inc. ("Loncor" or the "Company") (TSX: "LN"; OTCQX: "LONCF”; FSE: "LO51") is pleased to announce a 44% increase in mineral resources at its Adumbi deposit in the Imbo Project (Loncor 84.68%) in the D.R. Congo.
Compared to the inferred mineral resource of 2.19 million ounces of gold (28.97 million tonnes grading 2.35 g/t Au) outlined in April 2020 (see Company press release dated April 17, 2020), further drilling has now increased the Adumbi inferred mineral resource by 44% to 3.15 million ounces of gold (41.316 million tonnes grading 2.37 g/t Au), constrained within a US$1,500 open pit shell (see Figures 1 and 2 below). 84.68% of this inferred mineral resource is attributable to Loncor via its 84.68% interest in the Imbo Project.
Table I below summarises the Adumbi inferred mineral resource based on in-situ block cut-off at a 0.68 g/t Au for Oxide and Transition materials and 0.72 g/t Au for Fresh material, and constrained within a US$1,500 per ounce optimized pit shell.
Table I: Adumbi Deposit Inferred Mineral Resource by Material Type
(effective date: April 27, 2021)
| Material Type | Tonnage
(Tonnes) | Grade
(g/t Au) | Contained Gold
(Ounces) |
| Oxide | 4,623,000 | 2.24 | 333,000 |
| Transition | 3,674,000 | 2.53 | 299,000 |
| Fresh | 33,019,000 | 2.38 | 2,521,000 |
| TOTAL | 41,316,000 | 2.37 | 3,153,000 |
Note: Numbers may not add up due to rounding.
Commenting on today’s inferred mineral resource increase at Adumbi, Loncor’s President Peter Cowley said: “This major increase in mineral resources within a US$1,500 pit shell to 3.15 million ounces of gold is an important milestone in demonstrating the potential economic viability of the Adumbi deposit. Sensitivities show this mineral resource within the pit shell is robust and not markedly sensitive to changes in the gold price. Gold mineralization is open at depth below the pit shell where drilling is continuing with the objective of outlining underground resources (see Figure 2 below). Drilling at Adumbi also demonstrates that grade is increasing at depth, which bodes well for a significant underground resource to be outlined. Going forward, once drilling has been completed in Q2 2021, we will embark on a Preliminary Economic Assessment (PEA) to determine the potential economic viability of Adumbi.”
This mineral resource assessment was undertaken by the Company’s independent geological consultants Minecon Resources and Services Limited (“Minecon”). The updated estimate for Adumbi was based on the additional drilling and a review of the Adumbi deposit including remodelling, grade and considering the CIM requirement for mineral resources to have “reasonable prospects for economic extraction”.
Drilling Results included in Mineral Resource Update
An additional six core holes totaling 2,557.25 metres were drilled with the initial focus in areas within the pit shell where insufficient drilling had been undertaken to outline mineral resources. Later drilling has and is being undertaken at depth below the open pit shell to outline potential underground mineral resources.
The following Table II summarises drill results incorporated into the April 27, 2021 mineral resource:
Table II: Core Hole Results from 2020-21 Drilling Program
| Borehole | From (m) | To (m) | Intercept Width (m) | Grade (g/t) Au |
| LADD001 | 202.58 | 223.35 | 20.77 | 1.72 |
| LADD001 | 231.27 | 237.17 | 5.90 | 1.89 |
| LADD001 | 251.27 | 258.60 | 7.33 | 5.80 |
| LADD001 | 295.25 | 298.70 | 3.45 | 2.10 |
| LADD001 | 301.62 | 321.95 | 20.33 | 2.47 |
| LADD001 | Incl.317.11 | 321.95 | 4.84 | 5.40 |
| | | | | |
| LADD003 | 224.55 | 235.00 | 10.45 | 3.88 |
| LADD003 | 253.50 | 286.80 | 33.30 | 3.25 |
| LADD003 | Incl. 253.50 | 259.20 | 5.70 | 7.00 |
| LADD003 | Incl. 277.73 | 286.80 | 9.07 | 5.11 |
| | | | | |
| LADD004 | 429.00 | 457.00 | 28.00 | 3.26 |
| LADD004 | Incl. 432.00 | 436.90 | 4.90 | 6.96 |
| LADD004 | Incl. 450.62 | 454.15 | 3.53 | 8.30 |
| LADD004 | 473.80 | 478.40 | 4.60 | 2.07 |
| LADD004 | 505.85 | 526.15 | 20.30 | 2.83 |
| LADD004 | Incl. 506.85 | 513.40 | 6.55 | 4.64 |
| LADD004 | Incl. 523.85 | 526.15 | 2.30 | 7.25 |
| | | | | |
| LADD006 | 299.37 | 302.25 | 2.88 | 2.64 |
| LADD006 | 308.00 | 309.00 | 1.00 | 21.20 |
| LADD006 | 322.10 | 337.30 | 15.20 | 1.67 |
| LADD006 | 353.35 | 357.85 | 4.50 | 3.25 |
| | | | | |
| LADD007 | 99.95 | 107.80 | 7.85 | 1.45 |
| LADD007 | 540.62 | 596.05 | 55.43 | 2.76 |
| LADD007 | Incl. 583.60 | 596.05 | 12.45 | 8.11 |
| LADD007 | 607.90 | 611.27 | 3.37 | 4.61 |
| | | | | |
| LADD008 | 235.05 | 278.15 | 43.1 | 1.68 |
| LADD008 | 291.8 | 298.9 | 7.1 | 1.34 |
| LADD008 | 305.15 | 305.93 | 0.78 | 21.8 |
| LADD008 | 323.8 | 338.78 | 14.98 | 3.62 |
| LADD008 | Incl. 335.75 | 338.78 | 3.09 | 13.28 |
| Notes: | 1. It is estimated that the true widths of the mineralised sections for core holes LADD001, LADD003, LADD004, LADD006, LADD007 and LADD008 are, respectively, 82%, 80%, 81%, 95%, 89% and 62% of the intercepted widths in the above table. |
| | 2. Deep core hole LADD009 results, which included 32.15 metres grading 6.17 g/t Au and 15.36 metres grading 3.73 g/t Au, are not included in current mineral resource update due to timing. |
| | 3. Core holes LADD002 and LADD005 were discontinued before intersecting mineralized zone. |
Core Logging & Geological Controls
Gold mineralization at Adumbi is found within a BIF (Banded Iron Formation) unit with a strike length of 850 metres and up to 130 metres in thickness (see Figures 3 and 4 below: Geologic Plan and Geologic Cross Section of the Adumbi Deposit). Four main zones of gold mineralization are present within the BIF and are located in:
- the upper part of the Upper BIF Sequence,
- the lower part of the Upper BIF Sequence separated by the Carbonaceous Marker, which is essentially unmineralized, and
- within the Lower BIF Sequence.
There is a higher-grade zone of gold mineralization termed the Replaced Rock Zone (“RP Zone”) associated with alteration and structural deformation that has destroyed the primary host BIF fabric. The RP Zone occurs in the lower part of the Upper BIF and in the Lower BIF, and transgresses the Carbonaceous Marker, located between the Upper and Lower BIF zones, both along strike and down dip.
Geological Modelling and Grade Estimation
The Adumbi 3-dimensional model was constructed by Minecon in collaboration with on site geologists using cross sectional and horizontal flysch plans of the geology and mineralization and was used to assist in the constraining of the 3-D geological model. The mineralization model was constrained within a wireframe at 0.5 g/t Au cut-off grade (see Figure 5 below). Grade interpolation was undertaken using:
- 2 metre sample composites capped at 18 g/t Au to improve the reliability of the block grade estimates.
- Ordinary Kriging to interpolate grades into the block model.
- Relative densities of 2.45 for oxide, 2.82 for transitional and 3.05 for fresh rock were applied to the block model for tonnage estimation.
Pit Optimisation Parameters
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 gold price of US$1,500 per ounce.
- 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 (no additional metallurgical studies have been undertaken since the April 2020 resource).
- Average mining cost of US$3.29/tonne mined.
- Average processing cost of US$22.02/tonne processed.
- Average general and administration cost of US$4.20/tonne.
- Mineral resources were estimated at a block cut-off grade of 0.68 g/t Au for oxide and transition materials and 0.72 g/t Au for fresh material constrained by a Whittle pit.
- 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 RPA study of 2014 and the same total amount of material was used by Minecon.
Gold Price Sensitivities
Sensitivities were undertaken around the base case US$1,500/ounce gold price, and tonnage and grade are summarised in the graph below:
Tonnage/Grade Variation Graph Related to Gold Price Sensitivities
https://www.globenewswire.com/NewsRoom/AttachmentNg/5ef09afc-1619-4092-b7c7-23509699fa91
Adumbi Deposit Variation of Grade and Contained Gold with Depth
Panel evaluation of the mineral resource at 100 metre intervals without any pit constraint has demonstrated an increase in gold grade with depth from 300 metres and demonstrates the depth potential of the Adumbi deposit. Table III and the graph below details the increased grade with depth of the Adumbi resources.
Table III: Adumbi Mineral Resource, Panel Evaluation at 100 metre Intervals
DEPTH
FROM
(m) | DEPTH TO
(m) | PANEL
(m) | TONNAGE
(tonnes) | GRADE
(g/t) | CONTAINED Gold
(Moz) |
| 0 | 100 | 100 | 9,052,000 | 2.25 | 0.65 |
| 100 | 200 | 200 | 10,482,000 | 2.03 | 0.6 |
| 200 | 300 | 300 | 9,388,000 | 1.91 | 0.58 |
| 300 | 400 | 400 | 8,331,000 | 2.29 | 0.61 |
| 400 | 500 | 500 | 7,853,000 | 2.82 | 0.71 |
| 500 | 600 | 600 | 3,959,000 | 3.56 | 0.45 |
Note: Low tonnage for 600 Panel (500-600m) due to insufficient drill density, which is being addressed with ongoing drill program.
The graph accompanying Table III is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/d55f18f1-b6fa-422c-9b74-3024707b7a93
The Adumbi deposit is found within Loncor’s Imbo Project, which contains two other deposits, Kitenge and Manzako. As a result of the increased mineral resource at Adumbi, the total inferred mineral resource of the Imbo Project is now 3.466 million ounces of gold (42.996 million tonnes grading 2.51 g/t Au) and is summarised in Table IV below. 84.68% of this inferred mineral resource is attributable to Loncor via its 84.68% interest in the Imbo Project.
Table IV: Inferred Mineral Resource for the Imbo Project (effective date: April 27, 2021)
| Deposit | Tonnage
(Tonnes) | Grade
(g/t Au) | Contained Gold
(Ounces) |
| Adumbi | 41,316,000 | 2.37 | 3,153,000 |
| Kitenge | 910,000 | 6.60 | 191,000 |
| Manzako | 770,000 | 5.00 | 122,000 |
| TOTAL | 42,996,000 | 2.51 | 3,466,000 |
Note: Numbers may not add up due to rounding.
Combined with the Company’s Makapela Project, which is situated approximately 50 kilometres northwest of the Imbo Project, total mineral resources at Loncor’s properties in the Ngayu belt now stand at 4.016 million ounces of inferred mineral resources (46.216 million tonnes grading 2.70 g/t Au) and 0.614 million ounces of indicated mineral resources (2.205 million tonnes grading 8.66 g/t Au ).
Quality Control and Quality Assurance
Drill cores for assaying were taken at a maximum of one-metre intervals and were cut with a diamond saw, with one-half of the core placed in sealed bags by Company geologists and sent to the Company’s on-site sample preparation facility. The core samples were then crushed down to 80% passing minus 2 mm and split with one half of the sample up to 1.5 kg pulverized down to 90% passing 75 microns. Approximately 150 grams of the pulverized sample was then sent to the SGS Laboratory in Mwanza, Tanzania (independent of the Company). Gold analyses were carried out on 50g aliquots by fire assay. In addition, check assays were also carried out by the screen fire assay method to verify high-grade sample assays obtained initially by fire assay. As part of the Company’s QA/QC procedures, internationally recognized standards, blanks and duplicates were inserted into the sample batches prior to submitting to SGS Laboratory.
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