Saturn said in January aggressive drilling in 2020 increased the indicated and inferred resource within a Whittle-constrained, 250m-deep openpit to 944,000oz (35.9 million tonnes grading 0.8gpt). The company aims to complete another 50,000m this year with a view to posting a further update sometime later in 2021. As well as along-strike extensions and potential joining of higher-grade shoots within the main Apollo Hill resource area, Saturn has the treasury and key investor backing to pursue an ambitious regional discovery agenda.
North American investment group Sprott Capital says in its latest note on Saturn new extension drilling results continue to highlight the potential to add ounces in a 1.4km (so far) corridor between the main Apollo Hill resource and the Tefnut satellite deposit to the south-west. Assays from about 4,000m of RC drilling in 30 holes are still awaited.
Major resource-equity investor Sprott has a share-price target on Saturn more than double current trading levels, which it pins to resource-growth prospects evidenced by recent and ongoing drilling plus an aggressive new regional program. It says the unique metallurgical properties of Apollo Hill could also produce an "exciting step-change", with further demonstration of high sulphide heap leach recovery rates leading to a lower cut-off grade and a "quick 1Moz reserve".
Sprott says the heap leaching potential at Apollo Hill is one of several key value drivers for Saturn, which has 1,000sq.km of ground on one of Western Australia's (and the world's) most prolific gold belts and technically strong leadership that has driven efficient exploration capital allocation to date.
Bamborough, a former senior exploration geologist with Newmont Mining, says Saturn has added 439,000oz of resource at Apollo Hill since its March 2018 IPO, converting 21.2Mt grading 0.8g/t to 556,000oz of indicated resource (59% of the current total) and effectively delivering 5.4oz of indicated resource for every metre drilled so far.
With more than A$12 million in the bank at the time of writing, Saturn hasn't "gone into an exploration season with such a strong cash position".
"We're set up for an excellent year," he says.
"We want to show as quickly as possible the potential to take that next step up with the resource, and we're only going to do that by exploring.
"But we have identified a large-tonnage, low-strip, single, simple pit about 500m wide and up to 1.4km long, with an average grade that works for a number of reasons, including geometry and simple metallurgy.
"It's worth noting that in the last year we've seen the five best intersections we've ever seen across our entire land holdings on this major greenstone belt come up within this deposit. We're actually starting to see the high-grade shoots coming together now - in some very respectable intersections, and widths - within that big low-grade system, so the exploration focus continues there as well.
"Within that [low-grade body] there is a higher-grade architecture and, as I say, in the last three years we've seen some of the best intersections we've seen in the last 30-odd years."
Latest results from drilling outside the current Apollo Hill resource envelope continue to highlight potential extensions and the overall fertility of an area that is only now being subjected to a sustained and systematic exploration effort in an era when multi-million-ounce deposits and large-scale mines have sprung up across the Leonora belt.
Bamborough, who has spent a good part of his career working in the region, says 65% of Saturn's 1,000sq.km tenement package doesn't have a single drill hole on it while only the Apollo Hill area has seen sustained drilling below 150m.
"These deposits never really occur on their own," he says, and highlights continuing early success at Calypso, only 3.5km east of Apollo Hill, where Saturn has a 5,000m drilling program following up intercepts such as 9m of 8.67gpt from 115m below alluvial cover.
"We're doing aircore drilling out there now … with the aim of opening up that corridor.
"It's definitely something to watch for this year," Bamborough says.
Step-out drilling and resource modelling pointing to "a beautiful plunge" in the Apollo Hill mineralised system to the south of the main resource provided a clear focus for this year's drilling outside the infill work planned for the large, central deposit.
"We had never drilled to the south and the north. That drilling is happening in earnest now and producing results," Bamborough says.
"We've stepped out up to 900m south of the main deposit, where we think some of the plunging shoots in Apollo Hill are coming to the surface, and I'm happy to say we've seen some excellent drill results and nice-looking geology."
Latest assays from RC holes along the Ra-Tefnut corridor include 19m grading 1.18gpt from 26m, including 10m of 2.01gpt, and 8m of 9.47gpt from 102m. In late March Saturn reported an intercept of 12m at 1.32gpt from 124m. Importantly, strongly mineralised intersections are being "repeatedly returned in shallow extensional positions on this major emerging corridor", the company says.
"What I want to do over the coming weeks and months is demonstrate the capacity to make that next step change in the deposit," Bamborough says. "How are we going to do that? Lots of drilling."
While efforts to demonstrate the wider potential at Apollo Hill and over Saturn's big chunk of the regionally significant Keith-Kilkenny Shear and boost the central resource will no doubt sustain interest in its aggressive drilling program this year, the company also continues to move the project along the development path.
Bamborough says grade-control drilling on selected "panels" within the modelled Apollo Hill pit shell are aimed at showing the continuity of the deposit - and produce an "excellent bank of samples for metallurgical testwork".
"… the most important takeaway is the uniquely high recoveries of fresh-material"
"We've got some beautiful options for processing this in a very simple way," he says.
"One of the things we have to do is clearly differentiate this deposit from [what the market sees as] a normal Yilgarn deposit. It does sit in a unique position because of this single, gravity-focused mineralogy.
"A lot of the gold is quite coarse and sitting in these quartz veins. What that means is cheap, physical processing; about 60% gravity. Even at the coarsest commercial grind-size of 300 micron we've seen recoveries of 92% or more. That means lower energy use on grinding, low cyanidation, no preg-robbing materials, no carbon or arsenic.
"And then another option that has become increasingly apparent is heap leaching.
"As we looked at the heap leach characteristics we were absolutely delighted to see recoveries in the high 60s and 70s [per cent] in column tests, within a very quick residence time - as few as 21 days. Most people avoid heap leaching in WA because there's a lot of clay, but this is fresh rock [with] lower agglomeration requirements. We've seen good percolation through the [test] piles. And importantly as well, a very flat grade recovery curve. So even at the lower grades of, say. 0.1gpt, we're getting about 80% recovery; at 0.37gpt it's 91% recovery, and that is quite unique.
"If you're getting paid to dig that dirt out of the pit [it's] essentially pushing the stripping ratio down [and] pushing my unit costs down. What we've found in the recent grade-tonnage curve is there is a much bigger opportunity out there if we can take this metallurgical testwork to the next level.
"I think a serious step-change can happen.
"Some of the biggest deposits in the world - Kinross Gold's Round Mountain [in Nevada, USA], for example, with a floating resource of about 100Mt at about a 0.64gpt head grade - work because of simple metallurgy."
Sprott says fresh-rock heap leaches are rare because the gold is normally sufficiently intercalated with sulphides to need grinding to liberate.
"The fresh ore [at Apollo Hill] is low-sulphide, and most gold is free gold, so HL recovery is remarkably high.
"At a 0.3gpt cut-off, we see 1.1Moz at 0.68gpt.
"If this was in Nevada that would be a prime high-grade asset. With much faster Australian permitting the value improves, offset by lower input costs in the US. This would improve continuity and lower strip also, as the lodes … could coalesce, lowering the strip.
"A 6Mtpa HL could see 95koz pa at under US$900/oz. It is too early to rely on this and the … economics should be considered very approximate, but the most important takeaway is the uniquely high recoveries of fresh-material."