Galileo Mining (ASX: GAL) - Callisto Palladium Recoveries and Mission Sill Drilling
ASX palladium explorer Galileo Mining has run new flotation tests on fresh Callisto drill core and recovered 79% to 85% of the palladium. Its next step is RC drilling at Mission Sill, on ground that earlier explorers drilled between 2000 and 2017.
Galileo Mining (ASX: GAL) is exploring for palladium and platinum at its 100%-owned Norseman project in Western Australia, where it found the Callisto deposit in 2022. On 28 October 2026 it reported new flotation tests on fresh Callisto drill core, and said RC drilling at the Mission Sill prospect would start in early November [R1]. Samso has followed the company since 2020, mostly through interviews with Managing Director Brad Underwood.
All prices in this piece are as at the close of ASX trading on 6 November 2026.
The Callisto Metallurgy Announcement
Galileo released Strong Metallurgical Recoveries at Callisto Ahead of Mission Sill Drilling to the ASX on 28 October 2026 [R1]. It covers new metallurgy on fresh Callisto core, the aircore drilling just finished and the RC drilling about to start.
ALS Metallurgy, a commercial laboratory, ran seven flotation tests on a 12-metre sample of Callisto core. Flotation is the standard way to treat this kind of rock. The rock is ground fine and stirred in water with reagents, and air is bubbled through it. The sulphide minerals that carry the metals stick to the bubbles and float off as a concentrate. Recovery is the share of each metal that ends up in that concentrate.
The sample came from 147 to 159 metres in diamond hole 26NRDD525, drilled through the Callisto resource in March 2026 [R8]. Diamond drilling recovers solid rock core.
Aircore drilling is finished at North Callisto, about 2 km north of the resource, along reconnaissance lines further north, and at the South Callisto gold prospect. The program drilled 3,568 metres in all, with assays expected in about six weeks [R1]. Aircore is low-cost, shallow drilling that samples the weathered rock near surface. RC drilling of about 2,000 metres at Mission Sill is due to start in early November. RC, or reverse circulation, drills deeper and brings up chips of fresh rock, which is the hard rock below the weathered zone. North Callisto and Mission Sill are on PGM contacts Galileo has mapped across its Norseman ground (FIG. 01).
Highlights of the Callisto Palladium Flotation Results
The sample's head grade, which is its grade before any treatment, was 2.05 grams per tonne (g/t) palladium, 0.32 g/t platinum, 0.10 g/t gold, 0.43% copper and 0.39% nickel (TABLE 01).
![TABLE 01. Callisto flotation tests on the 26NRDD525 composite, 147 to 159 metres. Head grade, and the range of recoveries and concentrate grades across seven tests. Columns: Metal, Head grade, Recovery, range, Concentrate grade, range. Metal Palladium; Head grade 2.05 g/t; Recovery, range 79.0% to 85.1%; Concentrate grade, range 10.5 to 18.1 g/t. Metal Copper; Head grade 0.43%; Recovery, range 86.6% to 94.2%; Concentrate grade, range 2.79% to 3.93%. Metal Nickel; Head grade 0.39%; Recovery, range 69.0% to 75.1%; Concentrate grade, range 1.94% to 2.76%. Metal Platinum; Head grade 0.32 g/t; Recovery, range 70.6% to 76.4%; Concentrate grade, range 1.47 to 2.15 g/t. Metal Gold; Head grade 0.10 g/t; Recovery, range 71.1% to 81.6%; Concentrate grade, range 0.57 to 1.06 g/t. Source: Galileo Mining, ASX release 28 October 2026, Tables 1 and 2, page 3 [R1]. Ranges are Samso's summary of the seven tests. The release does not say whether these are first-stage (rougher) or upgraded (cleaner) concentrates.](https://static.wixstatic.com/media/8d6c37_f3f97a7e502349dfab5f384abf3f42f4~mv2.jpg/v1/fill/w_980,h_441,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/8d6c37_f3f97a7e502349dfab5f384abf3f42f4~mv2.jpg)
Galileo's 2023 tests on Callisto core recovered 82% of the palladium and 94% of the copper at a standard grind of 75 microns. The 2023 resource assumed those recoveries [R1] [R4].
At the same 75-micron grind, the three new tests recovered 79.4% to 80.9% of the palladium. The four tests at a coarser 98-micron grind recovered 79.0% to 85.1% [R1].
The best palladium result, 85.1%, came from one coarse-grind test. Coarser grinding uses less power, and the release says more work is needed on how grind size affects recovery [R1].
The sample is richer than the resource as a whole. It came from the highest-grade part of the resource zone in that hole [R1].
The Callisto resource is 17.5 million tonnes at 1.04 g/t 4E, 0.20% nickel and 0.16% copper, in the Indicated and Inferred categories, the middle and lowest of the JORC Code's three confidence levels, reported in October 2023 [R1] [R3]. 3E is palladium, platinum and gold together. 4E adds rhodium.
The fresh core floats close to the 2023 results, with most tests a little under the 82% the resource assumed. How lower-grade Callisto rock behaves is still to be tested.
What the Old Drill Holes Show at Callisto and Mission Sill
Much of Galileo's Norseman ground was drilled before Callisto was found. The release lists the earlier work [R1]. Anaconda Nickel drilled RC holes at Mission Sill in 2000 and 2001, looking for nickel and cobalt in the weathered rock. Australian Gold Resources (AGR) followed in 2003 and 2004 and confirmed shallow PGM results. PGMs are the platinum group metals, here mainly palladium and platinum.
Galileo took the ground over from AGR on 30 June 2004 [R1]. Galileo was then called PlatX, and it reported to the state under that name up to 2017 [R3] [R5] [R7]. Mark Creasy and his companies, AGR among them, held 27.53% of Galileo at 20 August 2026 [R3].
At Callisto, PlatX was working on the Mt Thirsty cobalt-nickel laterite, a deposit in the weathered rock above what is now Callisto. A laterite is a layer of deep weathering where some metals build up. In early 2016 PlatX drilled RC holes into electromagnetic (EM) conductors, which are rocks that carry an electric current and often hold sulphides or graphite. PlatX's table reports MTRC086 at 132 to 150 metres with 586 parts per billion palladium, about 0.59 g/t, and 1,240 parts per million copper, about 0.12% [R6]. PlatX called it a minor zone of sulphides carrying copper and PGMs [R6].
A second hole, MTRC096, reported to the state in 2017, hit palladium and copper over a similar depth [R7]. Galileo's section through the Callisto discovery shows both holes at the western end of the deposit (FIG. 02) [R4]. Galileo says Callisto was discovered about 100 metres below cover [R2]. PlatX described its PGM hits there as minor [R6]. For us, that is a reason to look closely at the other contacts around Callisto.
Anaconda Nickel, AGR and PlatX all drilled at Mission Sill. Galileo's map shows the old laterite and nickel holes across Zones A and B (FIG. 03). The earlier explorers found PGMs mostly in the weathered rock near surface. PlatX's 2009 report said, “generally these did not show similar enrichment in the unweathered rock” [R5]. For one drill section it gave two possible reasons. Weathering may have moved the metals and concentrated them near surface. Or the drilling may have missed a narrow primary zone, or one lying at an angle the holes did not test [R5].
Galileo's RC holes of December 2025 found sulphides carrying PGMs in fresh rock in both Zone A and Zone B [R1] [R3]. The best by grade and width combined was 17 metres at 0.36 g/t 3E from 84 metres in NRC519, including 5 metres at 0.61 g/t [R1] [R3]. These are downhole lengths, and the true widths are not known. The release says NRC516 ended while still in mineralisation [R1].
What Comes Next at Mission Sill
The RC program tests the fresh-rock sulphides down dip and along strike [R1]. Down dip means deeper on the same rock layer as it slopes into the ground. Along strike means further along the layer at the surface.
What we still need to know is whether the grades build as the holes go deeper. The RC results should help show whether the shallow PGMs came from weathering or from a primary zone the old holes did not reach.
Leadership Commentary
The release quotes Managing Director Brad Underwood [R1].
“The metallurgical results from Callisto resource diamond drill core are very encouraging, showing excellent metal recoveries from conventional grinding and flotation. This outcome gives us confidence that any further sulphide discoveries at Norseman are likely to respond in a similarly positive fashion given the comparable geology of our target prospects.”
A Coffee with Samso interview with Brad Underwood is in production. All eyes and ears should look out for it when it is published.
Near-term Milestones to Watch
Aircore assays from North Callisto, the reconnaissance lines and South Callisto, about six weeks from 28 October, which is around 9 December 2026 (our arithmetic).
Mission Sill RC drilling of about 2,000 metres from early November.
Further metallurgical work on grind size and recovery.
Samso Concluding Comments
Galileo has a resource at Callisto. The new tests show that fresh Callisto core floats much as the 2023 tests did. Galileo is now testing whether the same kind of rock repeats along its contacts. Metallurgy is one of the questions a resource has to answer before anyone can put a value on it. Recoveries of 79% to 85% of the palladium on a richer-than-average sample are a good start. A flowsheet, the full design of a processing plant, comes much later and needs far more test work.
Galileo had about A$6.9 million in cash at 30 September 2026, down from about A$7.5 million at 30 June [R2] [R3]. It spent A$582,000 on exploration in the September quarter [R2]. For an explorer the money is there to be spent on drilling. At the September quarter's pace the balance would last close to three years (our arithmetic). Drilling quarters spend faster. At 10 cents a share on 197.6 million shares, the market values Galileo at about A$19.8 million (our arithmetic).
SAMSO TAKE The next few months should start to show whether Callisto-style rock turns up elsewhere on Galileo's ground at Callisto's grade or better. Galileo reads the metallurgy as saying that if it does, it should treat the same way. How much weight would you put on Galileo's December fresh-rock sulphides, against the shallow results earlier explorers could not trace deeper? |
THE OTHER WAY TO READ THIS Anaconda Nickel, AGR and PlatX drilled Mission Sill between 2000 and 2017, and PlatX offered weathering as one explanation for the shallow PGM results [R5] [R7]. Galileo's best fresh-rock intercept at Mission Sill so far is 17 metres at 0.36 g/t 3E [R1] [R3]. Callisto's resource grade is 1.04 g/t 4E, which also counts rhodium. The RC drilling may yet support the weathering explanation. |
Previous Samso Coverage of Galileo Mining
Every earlier Samso post on Galileo, newest first. The gold rows are Coffee with Samso interviews rather than written pieces.
CALLISTO AND THE PALLADIUM STORY
5 JAN 2023 COFFEE WITH SAMSO Delivering Success: Building a PGE Resource Episode 168. Brad Underwood on building the Callisto resource in 2023. |
18 AUG 2022 COFFEE WITH SAMSO The Start of a Compelling PGE Story Episode 152. The Callisto discovery and the path to a resource. |
26 MAY 2022
Rooster Talk 57. The first RC results that confirmed Callisto.
22 APR 2022 COFFEE WITH SAMSO One Step Closer to more Sulphides Episode 140. The drilling campaign at Norseman ahead of the discovery. |
24 NOV 2021
Rooster Talk 51. The first sulphides found at Norseman.
5 NOV 2021
Rooster Talk 50. The start of palladium exploration at Norseman.
FRASER RANGE NICKEL, BEFORE CALLISTO
23 AUG 2021 COFFEE WITH SAMSO An Alternate Source for Nickel in the Albany Fraser Province for Galileo Mining? Episode 98. Nickel sulphide drilling in the Fraser Range. |
24 MAY 2021 COFFEE WITH SAMSO The Search for Nickel and Palladium - A Methodical Exploration Strategy Episode 87. How Galileo explores, and why it takes time. |
22 DEC 2020 COFFEE WITH SAMSO Bullish Outlook for Nickel Sulfide in the Year of the Ox: 2021 Episode 58. The Fraser Range nickel outlook for 2021. |
28 AUG 2020
Rooster Talk 25. The science of nickel sulphide exploration.
28 JUN 2020
Rooster Talk 21. Drilling at the Fraser Range nickel project.
12 MAY 2020 COFFEE WITH SAMSO Episode 36. The first Samso interview with Brad Underwood. |
THE VOCABULARY, IN PLAIN ENGLISH PGMs Platinum group metals. At Norseman these are mainly palladium and platinum. g/t Grams per tonne. The weight of metal in each tonne of rock. 3E and 4E 3E is palladium plus platinum plus gold, in grams per tonne. 4E adds rhodium. Flotation A process that grinds rock fine and bubbles air through it in water, so the metal-bearing minerals float off as a concentrate. Recovery The share of a metal in the rock that ends up in the concentrate. Head grade The grade of a sample before it is treated. Grind size How fine the rock is ground before flotation. A coarser grind uses less power. Aircore drilling Low-cost, shallow drilling that samples the weathered rock near surface. RC drilling Reverse circulation. Deeper drilling that brings up chips of fresh rock. Diamond drilling Drilling that recovers a solid core of rock. Fresh rock Hard rock below the weathered zone. Metals found near surface may not continue into it. Indicated and Inferred Two of the three JORC Code confidence levels for a resource. Inferred is the least certain, Indicated the middle. Laterite A layer of deep weathering where some metals, such as nickel and cobalt, build up. EM conductor A rock that carries an electric current in an electromagnetic survey. Often sulphides or graphite. Sill A sheet of once-molten rock that cooled between other rock layers. Callisto is in one. Down dip and along strike Deeper on a rock layer as it slopes into the ground, and further along it at the surface. Open-file report An old company report the WA Government makes public, searchable in WAMEX. |
References and Sources
Every source carries an [R#] identifier, and the same identifier appears in the text where the source is used. FIG. 01, FIG. 02 and FIG. 03 are reproduced from Galileo Mining's public ASX documents. TABLE 01 is Samso's summary of figures in the 28 October 2026 release. The open-file reports are public WA Government records in WAMEX.
[R1] Galileo Mining, Strong Metallurgical Recoveries at Callisto Ahead of Mission Sill Drilling, ASX release, 28 October 2026. Link
[R2] Galileo Mining, Quarterly Activities Report, September 2026, ASX release, 26 October 2026. Link
[R3] Galileo Mining, Annual Report 2026, ASX release, 17 September 2026. Link
[R4] Galileo Mining, Investor Presentation, September 2026. FIG. 02 is from slide 7. Link
[R5] PlatX, Mt Thirsty Annual Report 2009, WA open-file report A84162, DMPE WAMEX. Link
[R6] PlatX, Mt Thirsty annual report and drill data to 30 June 2016, WA open-file report A109674, DMPE WAMEX. Link
[R7] PlatX, Mt Thirsty annual report and drill data, 2017, WA open-file report A114619, DMPE WAMEX. Link
[R8] Galileo Mining, New Diamond Drill Results Supports Potential for Multiple PGM Intrusive Systems, ASX release, 13 May 2026. Link
Cover photo. Galileo Mining, ASX release 6 October 2026, Norseman Drill Program Underway, Figure 1, page 1.
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