Aston Minerals : Petrology confirms that nickel is associated with sulphides

ASX ANNOUNCEMENT

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10 March 2022

Petrology confirms that nickel is associated with sulphides: pentlandite-millerite-heazlewoodite

Key Highlights

• Initial petrographic analysis conducted on seven drill core samples from DDED21-075 and 076 has confirmed sulphide affinity with respect to nickel mineralisation
  o Partial digest versus total digest methods have demonstrated 93% liberation of nickel across all drill holes to date, confirming nickel is associated with sulphides
• The analysis has provided further context to the substantial nickel assay results to date and increased confidence that the nickel mineralisation is associated with conventional sulphide species that are highly amenable to extraction
• Nickel sulphide assemblage includes pentlandite-millerite-heazlewoodite. Estimated nickel tenor from scanning electron microprobe ranges from 8.4% to 62.0% Ni
• Lack of nickel associated with silicates is a result of the olivine minerals undergoing complete serpentisation
• No nickel alloys or arsenopyrite (or other arsenide minerals) identified at Bardwell
• 30kg sample of mineralisation from DDED21-076submitted for sighter metallurgical testwork. Metallurgical testing aims to confirm a broader distribution of Ni sulphide species through drill intersections, in-situ grain size and conventional flotation testing
  o DDED21-076intersected 163.5m at 0.52% Ni and 0.016% Co from 186.5m ending in mineralisation
• Millerite-heazlewoodite-pentlanditeassemblage is produced from BHP's Mt Keith and Yakabindie Operations
• Resource definition drilling ongoing at Bardwell targeting 1.2km of strike

Table 1: Empirical Formulas for Nickel Sulphide Minerals Identified at Edleston
Nickel Sulphide Mineral	Formula	Abbreviation	Ni%	S%	Fe%
Millerite	NiS	Mlr	62.0	35.0	<3
Heazlewoodite	Ni3S2	Hzl	72.0	27.0	<2
Pentlandite	(Ni, Fe)9 S8	Pn	33.5	33.0	30

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Figure 1: Photomicrographs (RL) of sulphide masses composed of a ternary mineral assemblage of pyrrhotite

(po), pentlandite (Pn), and chalcopyrite (Ccp)

Figure 2: Photomicrograph (RL) showing the dominant mode of Ni-sulphide mineralisation, consisting chiefly of magnetite (Mag), pyrite (Py; light grey/white) and heazlewoodite/millerite (Hzl; pale yellow) filling interstices between serpentinized olivine grains.

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Figure 3: Photomicrograph (RL, partially crossed polars) Ni-sulphide identified as heazlewoodite (Hzl) displaying

lamellar features; also visible are pyrite (Py) inclusions and massive anhedral magnetite (Mag)

Figure 4: Photomicrograph (reflected light; RL) showing the dominant mode of Ni-sulphide mineralisation, consisting chiefly of magnetite (Mag), pyrite (Py; light grey/white) and heazlewoodite/millerite (Hzl; pale yellow)

Aston Minerals Limited (ASX: ASO, 'Aston Minerals' or 'the Company') is pleased to provide an update on the initial petrographic analysis of nickel sulphide mineralisation from the Boomerang Nickel-Cobalt Target, Edleston Project, Canada.

Managing Director, Dale Ginn commented: "The petrographic analysis conducted has provided a definitive confirmation of the species of nickel sulphide present at Edleston. The nickel sulphide minerals identified at Edleston are commonly processed and recovered from multiple substantial nickel mining operations including that of BHP's Mt Keith and Yakabindie Operations. Of particular note is the lack of nickel alloy minerals, arsenopyrite and other arsenic bearing minerals at Bardwell. This correlates well with the nickel liberation analysis conducted previously by the Company which demonstrated that 96-100% of nickel was liberated at Bardwell from hole DDED21-076. Through

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the combination of both these independent methods of analysis we can conclude that the nickel is associated with sulphides and not with silicates or alloy minerals.

30kg of mineralised drill core has been submitted for metallurgical testing which aims to determine the optimal grind size for sulphide liberation and to conduct initial floatation testing.

We look forward to providing further updates with respect to both our current drilling underway at Bardwell and metallurgical testing updates as results become available."

Overview of Petrographic Analysis

Seven drill core samples were submitted to Process Mineralogical Consulting Ltd (PMC) for petrographic examination. Each sample was macroscopically examined and prepared as a polished thin section which were taken from representative zones of mineralogical and textural interest. All prepared polished thin sections were examined with a petrographic microscope in transmitted and reflected light. Additionally, interactive Scanning Electron Microscope (SEM) was completed to identify very fine-grained phases and provide further confirmation of optical observations.

						Table 2: Samples Selected for Petrographic Analysis
	Hole			From		To		Total		Nickel		Heazlewoodite/millerite		Pentlandite	Awaruite
								Sulphide%		Tenor%
								(Estimate)		(Estimate)
				283.1		283.18		7-10%		20.4		X
	DDED21-076			344.83		344.91		7-10%		34		X
				347.4		347.5		7-10%		34		X		x
				19.75		19.83		7-10%		8.4				X
	DDED21-075			179.51		179.59		<1%		62		X
			668.93		669.0		<1%		33.5		X
				728.93		729.0		<1%		33.5		X			Tr

Figure 5: Hand specimen photograph with polished thin section outline- DDED21-076, 347.40 - 347.50m

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The samples of mineralisation were selected on the basis that they represented a broad spectrum of grades encountered from drilling to date.

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Figure 6: DDED21-076- Drill core sample 344, 1.47% Ni at 332.66m

The petrographic analysis has provided further context to the substantial nickel assay results to date and provides increased confidence that the nickel mineralisation is associated with conventional sulphide species. Of particular note is the fact that only trace detection of awaruite, a nickel alloy mineral, was identified in a single sample from DDED21-075.DDED21-075, located 3.5 km to the north of Bardwell intersected 730.9m at 0.23% Ni and 0.010% Co, starting at 13.1m ending in mineralisation.

The presence of awaruite identified in petrography from hole DDED21-075 correlates well with the comparison of aqua regia versus 4 acid digest results. DDED21-075 reported 91% liberation which based on the petrographic observations is likely due to iron alloy minerals comprising the majority of the 9% of nickel that wasn't liberated. In contrast, at Bardwell, DDED21-076 reported 96-100% liberation with the only nickel associated minerals being sulphides.

Table 3: Comparison of Aqua Regia (partial digest) versus 4 Acid Digest (total digest)

Hole	From (m)	Interval	Ni %	Ni %	%
		(m)	Aqua Regia	4 Acid Digest	Liberation
			ICP		Ni
DDED21-075	13.1	730.9	0.21	0.23	91
DDED21-076	67.5	282.5	0.42	0.43	98
DDED21-076	186.5	163.5	0.5	0.52	96
DDED21-076	331.7	18.3	0.66	0.66	100

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