Golden Rim Resources (ASX: GMR) has delivered a 40% increase to the contained gold estimate at its flagship Kouri gold project in north-east Burkina Faso after adding 400,000 ounces of shallow gold mineralisation to the project’s maiden resource.
The upgraded indicated and inferred resource now sits at 32 million tonnes grading 1.4 grams per tonne gold for 1.4 million ounces of contained gold, at a revised lower cut-off grade of 0.3g/t gold (compared to the previous 0.5g/t gold) to approximately 115 metres below surface.
The new estimate – which includes a 54% increase for the indicated mineral resource to 4.3mt – was based on 42 additional reverse circulation drill holes for a total of 5355m.
The new cut-off grade is based on a heap leach processing route (compared to the previous tank leach processing), and is designed to improve the continuity and width of gold lodes comprising the mineral resource.
Auger drilling has outlined regional areas of bedrock anomalous gold at the project’s Guitorga West, Guitorga North and Kom prospects, which have been considered priority targets for the discovery of additional gold mineralisation to further upgrade the resource.
The Kouri project area is traversed for 16 kilometres by a major regional shear zone believed to be “exceptionally endowed” with gold mineralisation and home to several major gold deposits in Burkina Faso, including Kiaka (5.9Moz gold), Bomboré (5.2Moz) and Essakane (7Moz).
Some of the gold anomalies within the zone are associated with resource-related extensions to IP and magnetic anomalies, further enhancing their prospectivity.
Auger and channel rock chip samples as well as isolated drill intercepts were used to calculate an estimated Kouri exploration target between surface and 115m depth of between 8mt and 13mt at up to 1.4g/t gold, containing between 0.3moz and 0.6moz of gold.
Recent trenching outlined a new broad zone of gold mineralisation adjacent to the current mineral resource, providing evidence to support the potential discovery of new gold lodes and the achievement of the estimated exploration target.
Channel rock chip sampling across this new zone returned two parallel intercepts of 3.3m at 3.2g/t gold including 1m at 9.3g/t gold; and 23m at 2.5g/t gold including 1m at 38.8g/t gold.
Golden Rim cautioned the quantity and grade of the exploration target was “conceptual in nature”, and said it was uncertain at this stage if further exploration would result in further upgrades.
“We believe there is significant potential for considerably more ounces at Kouri,” said managing director Craig Mackay.
“The deposit remains open at depth and along strike and we still have large gaps in the immediate resource area which are yet to be drilled.”
The company is using auger drilling to systematically explore part of the shear zone which extends 12.5km southwest of the main Kouri project area and where limited previous exploration has been conducted.
Past results suggest the zone is potentially highly-prospective for gold which, if successfully delineated, could be added to the mineral resource.
The priority regional target area of Red Hill is believed to contain a strong bedrock gold anomaly associated with several intense magnetic high anomalies.
Drilling to date has returned significant gold intercepts of 11m at 2.2g/t gold from 77m including 2m at 7.7g/t gold and 1m at 4.6g/t gold from 114m; and 16m at 1.8g/t gold from 29m and 10m at 2.2g/t gold from 52m.
Regional exploration drilling will continue until mid-2019.
Golden Rim believes the most likely development scenario for the Kouri project will be open pit mining, which will take advantage of the moderately-dipping continuous style of mineralisation within sheet-like shears as well as its occurrence near surface within the currently-defined resource area.
Mr Mackay said the upgraded mineral resource at an elevation of 155m, or approximately 115m below surface, is considered to have good potential for economic extraction.
He said there are “reasonable expectations” additional drilling will define extensions to the lodes which will allow extraction of all mineralisation to this depth by open cut methods.
Further drilling and pit optimisation studies will be required before gold mineralisation deeper than 115m can potentially be added to the resource.
“The mineralisation is likely to extend beyond 200m below surface on average, which is the deepest extent of the current drilling, [but we will confirm this] with follow-up and future drilling,” he said.