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Oko West Project Guyana





Reunion Gold’s Oko West Project is a brand-new gold discovery in northwest Guyana located south of the historical “Oko” gold district. In 2020, Reunion Gold’s geochemical survey, trenching, and initial drill program discovered and confirmed the presence of gold mineralization in shear zones along the contact between a greenstone belt assemblage and a granitoid unit on the east edge of the project area. The mineralization coincides with a six-kilometre-long gold-in-soil geochemical anomaly. The northern 2.5 km of strike length of that geochemical anomaly, where most of the drilling has taken place, is referred to as the Kairuni zone. The southern 3.5 km of that geochemical anomaly (called the Takutu zone) remains largely untested and represents one of several priority exploration targets on the project. The ongoing drill program at the Kairuni zone has confirmed gold mineralization in the saprolite and unweathered rock, showing good continuity along its 2.5 km strike. The deepest hole drilled intersected strong gold mineralization at 575 m vertical depth (hole D-112), and the Kairuni zone remains open along strike and depth. 



The Oko West Project is in the Cuyuni Mining District, some 95 km west of Georgetown and accessible by the Puruni laterite road and trails from the towns of Bartica and Itabali on the Mazaruni river  (Figure 1). The Puruni road leads to the Toroparu mine and is currently being rehabilitated.

Mineral rights and agreement

The Oko West Project comprises a Prospecting License with an area of approximately 44 square kilometres  (Figure 1 and 2) held by Reunion’s Guyanese subsidiary. Reunion has an option to acquire a 100% interest in the project area from local entrepreneurs. 

Geology and mineralization


The Oko West Project area is underlain by a greenstone belt assemblage of rocks from the Barama Group, consisting of mafic volcanics flows, volcanoclastic sediments and granitic plutons of the Proterozoic age  (Figure 1). Reunion Gold discovered an entirely new gold deposit in these rocks at the eastern edge of the project area  (Figure 2).  

The sequence hosting the bulk of the Oko West gold mineralization is composed of siliclastic, volcanoclastic, and carbonaceous sedimentary rocks. This assemblage is 100-200 m thick and has an overall tabular shape, dipping steeply to the east and “sandwiched” between a “hangingwall” granitoid pluton to the east and a “footwall” granitoid sill to the west (Figures 5, 7 and 8). The sedimentary units are intercalated and strongly deformed; their spatial position is conditioned by their original deposition and polyphase folding. 

Silica, carbonate, sericite, and sulphide alteration characterize gold mineralization. The mineralized intervals are generally associated with boxwork or stockwork composed of quartz/quartz-carbonate shear veins and multiple generations of extension veins.

Exploration program

In 2019, Reunion Gold launched its exploration program, including geological mapping, stream sediment geochemistry, and a detailed airborne magnetic and radiometric survey.


n 2020, Reunion Gold did a soil geochemical survey with samples taken every 50 m along lines spaced 200 m apart. The survey defined a gold-in-soil anomaly with a strike length of approximately 6 km. The anomalies coincide with shear zones associated with the geological contact between a sequence of volcano-sedimentary rocks and granitic plutons and sills  (Figures 2 and 3).


The Reunion Gold followed up the geochemical survey with a mechanized trenching program designed to test the geochemical anomalies at shallow depths. The trenching program consisted of excavator-dug trenches with channel samples collected from weathered rocks on the trench walls. Thirty-three trenches were excavated at approximately 200 m intervals over the northernmost 2.5 km of the gold soil geochemical anomaly (the Kairuni zone), totalling over 7,500 linear meters.  Figure 4 and table 1 report the assay results from these trenches. The trenching program confirmed that gold mineralization extends into the weathered bedrock (saprolite).


On February 18, 2021, Reunion Gold reported assay results from the completion of its initial 1,000-meter diamond drilling program. These drill holes confirmed the vertical continuity of gold mineralization to 100 m in the saprolite below trenches 4, 9, 18 and 19.

The encouraging results from the initial drill program prompted Reunion Gold to launch a robust drill program to systematically test gold mineralization’s vertical and lateral continuity in the 2.5 km long Kairuni zone to a vertical depth of 250 m. The drilling program was initially designed with east-west drill “fences” spaced every 100 meters. This program began on June 17, 2021, with one diamond drill rig, and on July 25, Reunion Gold added a reverse circulation drill. In October 2021, it added a second diamond drilling rig. In April and June 2022, a third and fourth more modern diamond drill rigs were added to close the spacing between drill holes to a 50 m grid. As of November 9, 2022, the project had completed 197 diamond drill holes totalling approximately 39,300 meters and 289 reverse circulation drill holes totalling about 24,000 meters, mainly in the Kairuni zone (Figures 5 and 6).
The drilling completed has shown excellent results, indicating continuous gold mineralization over the 2.5 km long Kairuni zone and reaching a vertical depth of ~575 m in hole D22-112 (
Figure 7). This hole successfully tested the depth extension of the Kairuni zone in block 4 with a significant intersection of 3.68 grams per ton of gold (g/t Au) over 71.15 meters. Hole D22-112 shows the interbedded clastic sediments and volcanoclastic rock units typically hosting gold mineralization in the Kairuni zone. The total length of composites within this zone, ignoring unmineralized intervals, is approximately 134 meters (the lengths referenced here do not represent true width). This hole also represents one of the best holes reported in terms of grade and length.

The continuity and depth extension of the Kairuni zone is illustrated by a plan map, (Figure 5) and a longitudinal section (Figure 6). Figure 5 shows the distribution of gold mineralization and the collars of holes from the November 9, 2022, press release. Figures 7 and 8 show geological cross-sections of the mineralized rocks in the Kairuni zone. Tables 2 and 3 show the composite intersections and collar locations for diamond drill holes and RC holes.  

The current drilling program continues with five diamond rigs with a capacity of about 7,500 meters of core per month and two reverse circulation rigs. This should allow for an increase in the pace of drilling to ~ 30,000 m over the next four months compared to ~ 48,000 m of drilling over the previous 14 months. Drilling of the Kairuni zone observes 80-meter step-outs at depth and on strike, systematically demonstrating mineralization continuity.


More specifically, this program will:

  • Expand the potential resource between the currently outlined mineralized envelope in block 4 (~ 250 m deep) and the successful 575 m deep hole D 112.

  • Step out drilling along strike and at depth in blocks 1, 5 and 6 of the Kairuni zone.

  • Test the deposit at depths beyond 575 m.

Other targets

The current exploration program also includes proposed scout drilling to test three additional priority target areas on the Oko West Project, as shown in Figure 9. These targets include the Takutu zone, which represents the southern 3.5 km of the gold in soil geochemical anomaly, lying upstream from an area of significant alluvial workings. Reunion Gold started an initial 6,000 m drill program at Takutu using the reverse circulation (RC) rig to scout drill along the mapped shear zones. This program will be followed by diamond drilling of any new gold mineralization discovered. 

The Bryan target zone (number 3 in Figure 9) covers the potential hard rock source for an area of significant alluvial gold mineralization that has been mined downstream at the center of the project area. The third target area, the Carol zone (target 2), is immediately west of the Kairuni zone, where several gold soil anomalies are found over an area underlain by favourable geology. 


Additional work underway


  • Environment baseline studies: Environmental Resource Management (ERM) completed the planned environmental baseline work comprising the wet- and dry-season surveys of fauna and sampling surface and ground waters in October. Surface waters from local streams were also sampled for environmental DNA (eDNA) analysis to map aquatic fauna biodiversity using technology developed by NatureMetrics, a technique never previously used in the region. The wet and dry season results are being reviewed, and further work is being planned based on the results. The study of additional environmental baseline disciplines is planned for 2023. 


  • Geotechnical work: The Company engaged Newfields to perform an initial geotechnical assessment based on drill core and available drill data with the objective of defining possible slope angles for future expected pit designs.

  • Metallurgical studies: A variability test work program is underway with approximately four hundred samples submitted for bottle roll testing at Actlabs, Guyana. Samples are derived geographically across the strike length and depth of the mineralized system, and aim to demonstrate recovery variability across lithological units, weathering and grade profiles. Results are expected by year-end.

  • Power: The Company contracted Instream Energy Systems, a Canadian group specialized in electrical "run of river" power generation with hydrokinetic technology, to conduct a pre-feasibility study to investigate its use for the project. This technology uses modular in-stream equipment deployed in rivers without water reservoirs.

Figure 1: Oko West Project location showing access roads and regional geology.

Oko West project location showing roads and regional geology

Figure 2: Oko West Project Prospecting License area outline with geology soil geochemical anomalies.

Figure 2: Oko West Project area outline and geology showing soil geochemical anomaly.

Figure 3: Detail of soil geochemical anomalies divided into the Kairuni and Takutu zones.

Figure 3: Detail of soil geochemical anomaly divided into the Kairuni and Takutu zones.

Figure 4: Map of soil geochemical anomalies and highlighted trench results in Kairuni zone.

Figure 4: Map of soil geochemical anomalies and highlighted trench results.

Figure 5: Plan map of drill traces overlain on a level plan (at 0 m RL) of gridded Au grade x downhole interval length derived from significant intervals. 

Note: Only drill holes with newly released assays map of the Kairuni zone shown. Topography is from a LiDAR survey, and six exploration “blocks” are shown for ease of reference.


Figure 6: Inclined longitudinal section looking west of the Kairuni zone central part, showing the distribution of gold mineralization as contours of gold grade times downhole thickness (gm/t). 

Note: Red dots are drill intersections disclosed in the November 22 press release. 

Figure 7-11

Figure 7: Cross-section 701800N looking north (exploration block 4 – section B on figure 6). 


Notes: Hole D-112 reported the deepest intersection so far in the deposit. Intersections coloured green were reported in the November 22 press release. Significant intervals shown in the section are calculated using a 0.3 g/t Au cutoff, 2m minimum length, and 3 m maximum length for internal dilution.

Figure 8: Cross-section 702050N looking north (exploration block 1 - section A on figure 6). 


Note: Intersections coloured green were reported in the November 22 press release. Significant intervals shown in the section are calculated using a 0.3 g/t Au cutoff, 2m minimum length, and 3 m maximum length for internal dilution.

Figure 9: Three priority exploration targets at the Oko West project


Tables 1-3 show detailed trench, diamond drilling, and reverse circulation drilling results can be found in the links below labelled table 1: Trenching results, table 2: Diamond drilling composite results, and table 3: Reverse Circulation drill composite results.


Link to: Table 1: Trenching results

Link to: Table 2: Diamond drilling composite results

Link to: Table 3: Reverse Circulation drill composite results


Notes to the tables of composite results


Composite drill and trench intersections calculations:

  • Minimum composite grade of 0.3 g/t    

  • Minimum composite length of 2 m 

  • Cut off interval for inclusion is 0.3 g/t 

  • The maximum length of internal waste is 7 m   

  • Gold grades are uncapped.   

  • Mineralized intersection lengths are not necessarily true widths.

Sampling and analysis:


  • Trench samples are channels taken horizontally and continuously in in-situ weathered rocks (saprolite) at regular intervals on trench walls. Reunion considers channel samples as sub-horizontal "drill holes" given their continuity and representative rock mass.

  • Diamond drill samples consist of half of either HQ or NQ core taken continuously at regular intervals averaging 1.4 m, bagged, and labelled at the site core shed. 

  • Reverse circulation drill samples are obtained from a rotary splitter attached to a Metzke cyclone, weighed, bagged, and tagged at the drill site. 

  • Samples are shipped to the Actlabs certified laboratory in Georgetown, Guyana, respecting the best chain of custody practices. At the laboratory, samples are dried, crushed up to 80% passing 2 mm, riffle split (250 g), and pulverized to 95% passing 105 μm, including cleaner sand. 50 g of pulverized material is fire assayed by atomic absorption (AA). Initial assays with results above 3,000 ppb gold are re-assayed with a gravimetric finish. Certified reference materials and blanks are inserted at 5% of samples shipped to the laboratory. MSALabs, another certified laboratory in Georgetown, tests umpire samples generated by Actlabs.

  • Assay data is subject to QA/QC using acQuire software and management by an independent consultant.

Other parameters:


  • Drill and trench collar locations were surveyed by professional Guyana land surveyors using differential GPS and total stations.  

  • Diamond and reverse circulation drill holes are surveyed by down-hole equipment. 

  • Diamond drill core is oriented as frequently as possible.


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