Rupert Resources: The benefits of aggressive drilling

January 14, 2022

by Jane Lockwood, Spotlight Mining 

The Ikkari property, Finland

Aggressive spending on drilling during exploration is usually a good strategy for advancing a project quickly, and nowhere demonstrates that fact better than Rupert Resources’s (Rupert) (TSXv:RUP, OTCQX:RUPRF) almost 4 million oz (113.4 tonnes) Ikkari gold discovery in Finland. This project is remarkable not just for its size and quality, but also because the company took it from discovery to a maiden resource estimate in just 18 months, during a global pandemic, no less. 

Rupert has consolidated a 595 sqr. km (229.73 sqr. mi) land package in the Central Lapland Greenstone Belt, an area that only began to draw serious attention in 2009 with the opening of Agnico Eagle’s Kittila mine, now the largest primary gold producer in Europe. Since then, there has been something of a gold rush in the area, and Rupert has come out on top. Thomas Credland, Rupert’s Head of Corporate Development, explained the company’s early interest in the region: 

‘Central Lapland already hosted a number of other orogenic gold and base metal deposits comparable to greenstone belts such as the Abitibi in Canada, Birimian of West Africa and Eastern Goldfields of Western Australia, but it was apparent that it was extremely immature in terms of exploration activity – probably 100 years behind.’ 

The entire area around Ikkari is a swamp with no outcrop, and beneath that is glacial till from the last ice age that overlies the bedrock to a depth of between 5–40 m (16.4–131.2 ft). This meant that there was no option but to drill on the site, in contrast to Kittila and Rupert’s other deposit in the region, Pahtavaara mine, which were both discovered in outcrop. Between 2017 and 2019, Rupert focused on characterizing their assets on a broad scale. Naturally, they employed geophysical methods to get a better picture of what lay under the ground but, most importantly, they stumped up the cash for percussion drilling down to the base of the glacial till and got geochemical analyses from the interface between the till and the bedrock. This was vital as it was the only way to really know what sort of rock was hiding under all that cover. 

Thomas Credland explained that Rupert’s strategy in the area was guided by the discovery of Anglo American’s nearby polymetallic Sakatti deposit, which hosts the dizzying array of Ni-Cu-Co-PGE-Au-Ag mineralization. Base-of-till drilling was used to discover Sakatti, and Rupert took note of this success. The company also had a new geological model to work with, which suggested a 25 km (15.53 mi) regional structure underlay part of their property. Rupert geologists had identified a possible basin margin in the south-west of their land package, which was confirmed when they drilled sediments in that area, as opposed to volcanic rocks in the east of the property. The company performed ‘tram line’ drilling – two lines of sampling 100 m (328 ft) apart, covering a large area. They then followed up anomalous results with more closely-spaced holes, and the Ikkari resource was one of those. 

Core samples from Ikkari
Extensive drilling resulting in plenty of core has been the key to rapid resource estimation at Ikkari

At Ikkari, a single anomalous sample with 0.2 ppm gold was investigated with infill drilling on a 50 x 25 m (164 x 82 ft) grid, which turned up a cluster of samples with up to 1 ppm Au. At that stage, Rupert knew they had a significant geochemical anomaly on their hands, so from April 2020, they began focusing more drilling there. The first hole (hole 120038) intersected 54 m (177 ft) grading 1.5 g/t Au, and subsequent holes showed that the mineralized area was large, with an initial strike length of more than 500 m (1640 ft) and was also high-grade in parts. At Ikkari, 100% of holes to date have hit gold mineralization. 

It quickly became clear that the feature controlling gold mineralization at Ikkari was the unconformity between the komatiite-dominant Savukoski Group and the sedimentary Kumpu Group. As COVID-19 shut down much of the world, Rupert took extensive health and safety precautions at their site and drilled on. In September 2021, just 18 months after Ikkari’s discovery, they were able to define an estimated mineral resource of 3.95 million oz (111.98 tonnes) for the deposit, with cut-off grades of 0.6 g/t Au for open pit mining and 1.2 g/t Au for underground. 

Rupert has not slowed down after this major success and are now targeting their drilling efforts in a 60:40 ratio at Ikkari and other discoveries. News at the end of November announced grades from tighter drill spacing at Ikkari of up to 7.7 g/t Au over 30 m (98 ft), and at the satellite Heinä Central deposit, which was not included in the resource estimate, both high-grade copper and gold have been found over multiple intervals. 

Drilling at Ikkari
Drilling is still ongoing at the property, with the company working to both expand and better define the resource

It’s clear from Rupert’s example that aggressive drilling from the start of an exploration campaign can pay off immensely. Thomas Credland said that investors understood the need for such an approach due to the lack of outcrop and the fact that the non-productive overhead of the program becomes proportionally bigger the fewer meters that are drilled, so other juniors looking to make substantial discoveries in fresh territory might want to take note. 

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Issue 18 / 2022