The Boulanger Project is located approximately 40 km south of Cayenne, the capital of French Guiana. Access to the project is by National Road No. 2 and a laterite roads network (figure B1).
Figure B1: Map showing the location of Boulanger project mineral rights in relation to the city of Cayenne, road access and regional geology.
Mineral rights and option agreement
In July 2017, Reunion entered into an option agreement with Compagnie Minière de Boulanger (CMB) to acquire a 100% interest in the Boulanger, Central Brief, Devez North and the Devez South mineral concessions, and the Carapa exploration permit (previously known as Ste-Marie). The four concessions were recently renewed until December 31, 2033 and cover a total area of 38.42 km² (figure B3). The Carapa exploration permit (PER) covering 24.0 km² is valid until December 2021 and is renewable twice, for period of five years each.
The Saint-Michel prospect is within a one square kilometre small-scale mining permit (AEX) encircled by the 45.5 km² Chawari exploration permit (PER) application, and both were added in 2019 to the option agreement between Reunion Gold and CMB (figure B3). The option can be exercised at any time up to July 27, 2023. Reunion must pay € 1,000,000 to CMB upon exercise and € 1,000,000 upon receipt of the regulatory approval to transfer the mineral titles to Reunion.
Geology and mineralization
Paramaca (volcanic) and Armina (sedimentary) rocks of Proterozoic age, intruded by granites, underlain the Project area (figures B1, 2 and 3). These rocks underwent intense deformation, with evidence of hydrothermal fluids rich in sulphides and gold, expressed as quartz veins, pyrite, and locally intense tourmaline alteration. Gold mineralization occurs both in tension and shear zone veins. Tension veins are usually sub-horizontal, up to a few meters thick and discontinuous, and were the object of most artisanal mining in the past, which can be observed at the Crique Filon and Carapa prospects. Shear zone veins are subvertical, much more continuous, but have seen little exploration so far. Shear zone veining is observed at the Crique Filon and Carapa prospects, acting as "feeders" to the tension or extension veins (Figure B2). Reunion Gold believes that significant gold deposits can be identified at Boulanger by targeting exploration on the shear zone-hosted mineralization.
Figure B2: Outcrop at Doyle 1 target, showing subvertical shear veins feeding tension/extension quartz veins.
Mining and Exploration History
The Boulanger Project is in an area that has produced gold artisanally for over 100 years, both from alluvial and primary sources. CMB still carries out small-scale alluvial gold mining operations on the mining concessions. Asarco explored portions of the Project area in the 1990s, followed by Cambior and Iamgold. These operators conducted extensive geological mapping, nearly 7,500 soil geochemical samples, trenching, and over 12,000 meters of diamond drilling in the nineties. Still, they stopped short of publishing a mineral resource estimate for the several prospects in the area. This historical drilling focused on large and flat, but discontinuous, tension veins, not shear-hosted veins. The geological mapping and soil geochemistry done by Asarco also outlined several anomalous zones that require follow-up exploration.
Recent Exploration Work
Reunion compiled all historical data, relogged available drill core, and is systematically exploring the known prospects to understand gold mineralization controls. Reunion covered the entire Project area with a heliborne magnetometry and radiometry survey and did ground follow-up surveys using induced polarization. Based on this work, Reunion was able to generate targets some of which have been tested by diamond drilling.
The main prospects of the Boulanger Project are Crique Filon and St-Michel.
Figure B3: Schematic geological map of the Boulanger project area showing the Crique Filon, St-Michel, and Devez prospects. Note Doyle and Carapa trends in the Crique Filon prospect area.
Crique Filon prospect
This prospect straddles the limit between the Central Bief concession and the Carapa exploration permit (Figure B3) and focuses current alluvial gold production.
Mostly intermediate and mafic volcanic rocks characterize the local geology in contact with a granitic batholith to the south. These rocks underwent at least two tectonic events and are strongly deformed by folding and faulting/shearing. Reunion identified several NW/SE-trending mineralized shear zones in two main "trends": Doyle and Carapa (Figure B3). Most of the historical and recent work concentrated on these trends, in which several drill intersections defined mineralized shears several hundred meters in length.
The 44 mineralized holes drilled in the Doyle trend from 1996 to 2020 gave an average gold grade of 3.77 g/t. For the combined Doyle and Carapa trend, the 72 mineralized holes drilled for the same period gave an average grade of 3.42 g/t (both averages using a cut-off grade of 0.4 g/t).
The Doyle trend has been the object of most exploration work, including drilling. The area has extensive mineralized alluvial deposits, and various operators attempted to discover their primary gold sources. Asarco (the 1990s) and CMB (2016) explored the northwesternmost part of the Doyle trend (known as Doyle 1, 2, and 3 targets) with over 4,000 meters and 1,175 meters of drilling, respectively. Early in 2018, Reunion completed a 1,025-meter drilling program in the northeastern corner of the Central Bief concession to acquire structural information on the mineralized trends. Later in 2018, two Reunion drill holes (CB-18-08 and 09) tested the central part of the Doyle trend and hole CB-18-08 intersected significant gold mineralization (table B1 and figure B4), including visible gold, interpreted to be shear-controlled, and thus confirming the need to do follow-up drilling. During the second quarter of 2019, Reunion completed new IP survey lines to cover fold closures and better define drill targets. A 1,100-meter core drilling program followed this in seven drill holes. Finally, in 2020, Reunion drilled 2,000 meters in 13 drill holes on the Doyle trend's eastern part. Table B1 summarizes the most significant mineralized drill intervals.
Shear zone gold mineralization
Reunion's geological interpretation demonstrates several subparallel shear zones (or deformation zones – "DZ") in the Crique Filon prospect area with a combined strike length of over two kilometers. The 2020 drill program expanded the gold mineralization footprint in these multiple parallel shear deformation zones and tested three of the identified deformation zones (Figure B4 and Table B1). Eleven of the drill holes tested the deformation zone DZ3, averaging 156 meters in-depth, well into fresh rock, one additional hole tested DZ1, and another one tested DZ4. The 20 current and historical drill holes testing DZ3 show excellent mineralization continuity along two subparallel shears, one 700 meters long (DZ3a) and another 500 meters long (DZ3b) (Figure B4 and Table 1). Both shears are open on strike and at depth. Quartz veining, accompanied by tourmaline and sulphides (pyrrhotite and pyrite), characterizes this mineralization, hosted by well foliated and brecciated volcanic rocks. Visible gold was logged in two drill holes (CFD20-24 and 25).
The following link shows a 3D visualization of these mineralized shears:
Figure B4: Doyle trend map, showing schematic geology with deformation zones (DZ) and significant drill intersections.
Table B1: Compilation of current and historical diamond drilling done on the Doyle trend, Crique Filon prospect.
A: Composites calculated using these parameters:
o Minimum composite grade: 0.4 g/t
o Minimum composite length: 2 m
o Cut-off of interval to be included in composite: 0.4 g/t
o Maximum length of internal waste: 2 m
o When more than two assays are done for one sample, use average.
B: Lengths are not true geological widths.
C: Historical drill holes were completed and analyzed using somewhat different sample preparation and assay techniques by sources believed to be reliable, but they have not been verified.
Carapa trend (STM 1 and 2)
Reunion recently re-logged and re-sampled historical core from the Carapa trend, which was drilled by Iamgold in the 2000s. These trends were known as St-Marie (STM) 1 and 2 (Figure B3 and 5). In total, Iamgold or previous titleholders drilled over 5,500 meters in the Carapa trend area. They identified gold-bearing quartz/tourmaline-pyrite veins like those seen in the Doyle trend. At the STM 1 and 2 targets, drilling by Iamgold in 2015 outlined a historical mineral resource estimate along an NW-SE trending shear zone (STM 2). Flat extension veins (STM 1) are estimated to contain 22,000 ounces averaging 2.5 g/t at the indicated category and 36,000 ounces at the inferred category averaging 2.2 g/t. Reunion Gold proposes further investigating this trend, testing both the down-dip and lateral extension of the shear zone.
Table B2: Significant mineralized intervals from diamond drilling done by Iamgold
(Calculated using a 0.4 g/t Au cut-off, 2 m minimum length, and a maximum of 2 m internal waste. Only intervals with (Au x interval) > 10 gm/t shown. Results are based on ¼ core re-assays done by Reunion Gold)
Figure B5: St Marie (STM 2) target with IP chargeability background, historical drill holes, and proposed exploration holes. The shear zone is shown as a white dashed line.
In the last quarter of 2018 and the first quarter of 2019, illegal artisanal miners discovered primary gold mineralization at the headwaters of a creek on the south flank of a small hill at the center of an AEX held by CMB, which had previously finished mining alluvium in the area. The "garimpeiros" sunk shafts and adits and reportedly produced significant amounts of gold from the workings but were eventually expelled by the French police.
In June 2019, Reunion geologists mapped the area and identified 47 shafts and adits scattered over an area of 260 by 95 meters elongated in an NNE-SSW direction (figure SM 1). Systematic sampling of stockpiles of mineralized quartz vein material extracted and abandoned next to the shafts returned an average of 17.3 g/t gold from 42 samples with the highest assay at 45.9 g/t gold (Table 1). Stockpile masses vary from one hundred kilos to about 16 tons. The sampling of limited outcrop exposure returned assay results up to 18.2 g/t gold from a "grab" sample and up to 26.6 g/t gold over a one-meter channel sample. Reunion then covered an area 2 by 1.8 kilometers with an induced polarization geophysical survey, including the entire area of artisanal workings, which coincide well with a north-south trending chargeability anomaly.
In September 2019, Reunion carried out an 18 hole, 900-meter reverse circulation (RC) drill program, followed by 1,000 meters of diamond drilling across seven holes (Figure SM 1). These holes demonstrated that gold mineralization is hosted in strongly sheared graphitic shale with boudinaged quartz veins and pyrite boxworks. Tables SM 1 and 2 show relevant intersections from diamond and RC drill holes.
Figure SM 1: Schematic geological map of the St-Michel prospect area, showing the location of artisanal shafts and Reunion drill holes.
Table SM1: Significant mineralized intervals from diamond drilling done by Reunion
(Calculated using a 0.4 g/t Au cut-off, 2 m minimum length, and a maximum of 2 m internal waste.)
Table SM2: Significant mineralized intervals from reverse circulation drilling done by Reunion (Calculated using a 0.4 g/t Au cut-off, 2 m minimum length, and a maximum of 2 m internal waste.)
Gold grades from drill holes are substantially lower than those obtained from quartz vein-only material of artisanal miners' stockpiles, which practically excluded host rock material. The mineralization trend remains open along strike and at depth, and additional soil and IP chargeability anomalies are yet to be tested in the area. High-grade gold mineralization in the prospect is confirmed by a historical drill hole by Asarco, which intercepted 1.5 meters grading 22.2 g/t gold immediately to the southwest of the prospect in the 1990s. Cyanidation recovery tests of stockpile samples indicated an average gold recovery of 94% after 24 hours of direct cyanide leaching and 99% after 72 hours. Also, a gravity recovery test gave a recovery of 65.1%.
The work done so far shows that gold mineralization is hosted by graphitic shales and red siltstones from a distal turbidite sequence flanked by mafic volcanics. The high density of boudinaged and tightly folded quartz veins associated with sulphides occur along a northeast-striking subvertical trend interpreted as a shear zone. Additional studies are underway to assess gold mineralization's structural control along this newly discovered shear zone.