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 network of laterite roads (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 to acquire a 100% interest in the Boulanger, Central Brief, Devez North, and the Devez South mineral concessions along with the Carapa mining permit (previously known as Ste-Marie). The four concessions, which cover an area of 78.2 km², were originally granted to Compagnie Minière de Boulanger (CMB) by the French government in the late 1880 and early 1920s (figure B3). Due to recent amendments to the French mining code, all concessions expired on December 31, 2018. CMB has filed applications to renew the concessions for a total area of 39 km², which covers all the main exploration target areas. The concessions remain valid during the administrative process of the renewal file.
The Saint-Michel prospect is located within a one square kilometre small scale mining permit (AEX) encircled by the 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 up to July 27, 2021. Total required exploration expenses are US$ 4 million out of which 90% was completed as of March 31, 2020. To exercise the option, Reunion must pay 1,000,000 € to CMB upon exercise and 1,000,000 € upon receipt of all regulatory approvals.
Geology and mineralization
The Boulanger Project area is underlain by Paramaca (volcanic) and Armina (sedimentary) rocks of Proterozoic age, intruded by granites and metamorphosed to greenschist facies (figures B1 and B2). The Project area is characterized by 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 also observed at the Crique Filon and Carapa prospects, acting as “feeders” to the tension or extension veins (Photo B1). Reunion Gold believes that significant gold deposits can be identified at Boulanger by targeting exploration on the shear zone-hosted mineralization.
Photo B1: 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 has been carrying 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 m of diamond drilling in the nineties but stopped short from 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 (Figure B3).
Following the compilation of historical data and relogging available drill core, Reunion set out to systematically explore the known prospects, verify their relationships, and attempt to define mineral resources. Key new exploration tools brought to the project included a heliborne magnetometry and radiometry survey over the entire area, and induced polarization geophysical surveys over specific targets (figure B3). These tools generated new targets and helped update geological, geochemical, and geophysical interpretation.
Figure B3: Map of the Boulanger project area showing Crique Filon, St-Michel and Devez prospects, soil anomalies, RTP magnetic features, and general geology.
Crique Filon prospect
This prospect straddles the limit between the Doyle concession and the Carapa exploration permit, at the southern edge of the Boulanger Project area (figure B3).
The local geology is characterized by mostly mafic volcanic rocks 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. Exploration work done so far mapped several NW/SE-trending subparallel mineralized shear zones, which can be grouped in four “trends”: Doyle, Carapa, Nilson and STM 6 (figure B4). Most of the historical and recent work concentrated on the Doyle and Carapa trends, in which several drill intersections defined mineralized shears several hundred kilometres in length. The various drilling campaigns cut 88 near-surface mineralized intersections in 67 drill holes, averaging 3.4 g/t Au per hole (calculated using a 0.4 g/t Au cut-off, 2 m minimum length, and a maximum of 2 m internal dilution).
Figure B4: Map of Crique Filon prospect area showing topographic background, RTP magnetics, IP chargeability, interpreted shear zones and secondary structural fabric defining mineralized “trends”, and priority exploration targets.
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. The northwesternmost part of the Doyle trend (known as Doyle 1, 2 and 3 targets) was explored by Asarco in the 1990s with over 4,000 m of drilling and by CMB, with 1,175 m of drilling in 2016. CMB also mined primary gold mineralization and alluvial placer in the area. The most significant mineralized drill intervals are summarized in table B1.
Table B1: Significant mineralized intervals from diamond drilling done by Asarco and CMB (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)
In 2018, Reunion completed an initial 1,025 m drilling program to confirm historical mineralization in the northeastern corner of the Central Bief concession and to acquire structural information on the mineralized trends through oriented core drilling in fresh rock. Five of the nine drill holes testing the targets intersected gold mineralization in quartz veins with pyrite and tourmaline in shear zones hosted by mafic volcanic rocks (table B2). Visible gold was identified in hole CB-18-01A.
This first limited drilling program confirmed the presence of significant gold mineralization in the northeastern corner of the Central Bief concession. Review of outcrop and core geology, together with previous and new structural data, enabled Reunion to frame the structural context of the area, contextualizing the known gold mineralization with the local structural geology. Steep shearing with its associated gold-bearing quartz veins is associated with the inverse flanks of folds. Plunge of the folds is gentle and either to the west-northwest or the east-southeast. Flat lying and discontinuous tension veins are associated with these high-strain zones. A few of the drill intersections, like in holes CB-18-01A and 03, are interpreted as being associated with tension veins.
Later in 2018, two Reunion drill holes (CB-18-08 and 09) tested the central part of the trend and intersected significant gold mineralization (table B2 and figure B4), including visible gold in hole CB-18-08, interpreted to be shear-controlled, and thus confirming the need to do follow-up drilling.
During the second quarter of 2019, eight new IP gradient survey lines totalling eight kilometres were completed to cover fold closures of the 2018 survey at the Carapa exploration permit and Central Bief concession, along with four lines of pole-dipole array to provide additional information on the suspected fold closures and better define drill targets. This was followed by a 1,100-meter core drilling program in six drill holes in June. Of interest are the holes drilled at the eastern extension of a shear was cut by three significant intersects in hole CA-19-05 (table B2 and Figure B5)
Table B2: Significant mineralized intervals from diamond drilling done by Reunion Gold (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)
An additional 300-meter core drilling program in two diamond drill holes was done in September 2019 to follow-up on shear and tension vein mineralization identified in drill hole CA-19-05. Of interest are three significant intercepts:
Hole CA-19-06A: 16.56 g/t gold over 2.60 m. This high-grade section starting in saprolite from 11.94 m is a re- drill of the top section of hole CA-19-06 with insufficient core recovery.
4.66 g/t gold over 5.65 m, starting from 9.00 m in saprolite.
2.77 g/t Au over 6.50 m
It has become apparent that several subparallel shear zones occur in the Crique Filon prospect area. The recent drilling cut tension veins and strongly foliated and sheared andesitic volcanics associated with the two shear zones intercepted in CA-19-05. This confirms the interest of targeting for future drilling both the shear veins and their associated tension veins. These shear zones can be traced over 300 m and 200 m, respectively and remain open on strike and at depth. Several other attractive shear zones are found in the same area, to be further tested by drilling (figure B5).
Based on the interpretation of the available drilling data, Reunion Gold has identified over 2 km of total strike length of mineralized shear zones at the Crique Filon prospect, which are ready for drill and trench work. Subject to the completion of a financing, the Company intends to further test the lateral and down-dip extension and continuity of gold mineralization in these shear zones by completing a total of 5,000 meters in 30 holes over two phases of drilling (figure B5). The concept is to gain enough information to build open-pit mineable resources
Figure B5: 3D perspective of the Doyle and Carapa trends, showing mineralized shear zones in red, EW structural fabric in grey, significant intersections from Reunion drilling, and target zones (dark grey) with no drill testing.
Carapa trend (STM 1 and 2)
Reunion re-logged and re-sampled historical core from the Carapa trend, which was drilled by Iamgold in the 2000s and then known as STM 1 and STM 2 (St-Marie). In total, Iamgold or previous titleholders drilled over 5,500 m in the Carapa trend area and identified gold-bearing quartz/tourmaline-pyrite veins like those seen in the Doyle trend (figure B5 and table B4). At the STM 1 and 2 targets, drilling by Iamgold in 2015 outlined a historical mineral resource estimate along a NW-SE trending shear zone (STM 2) and flat extension veins (STM 1) 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 to further investigate this trend, testing both the down-dip and lateral extension of the shear zone.
Table B4: 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 B6: St Marie (STM 2) target with IP chargeability background, historical drill holes and proposed exploration holes. Shear zone is shown as 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 small 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 m by 95 m 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. 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 2x1.8 km 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 m of diamond drilling across seven holes (Figure SM 1). These holes demonstrated that gold mineralization is hosted in saprolite of 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 essentially 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. The presence of high-grade gold mineralization in the prospect is confirmed by a historical drill hole by Asarco which intercepted 1.5 m @ 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 indicates that gold mineralization is hosted by graphitic shales and red siltstones from a distal turbidite sequence flanked by mafic volcanics, with a high density of boudinaged and tightly folded quartz veins associated with sulphides, along a northeast-striking subvertical trend interpreted as a shear zone. Additional studies are now underway to assess the structural control of gold mineralization along this newly discovered shear zone.