OZ Minerals : Prominent Hill Mineral Resource & Ore Reserve Statement

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OZ Minerals Limited

PROMINENT HILL

Mineral Resource and Ore Reserve Statement and Explanatory Notes

As at 30 June 2021

Prominent Hill Mineral Resource and Ore Reserve Statement and Explanatory Notes As at 30 June 2021

For personal use only

SUMMARY

The June 2021 Prominent Hill Mineral Resource and Ore Reserve estimates are presented in Tables 1 and 2. The Mineral Resource is inclusive of the Ore Reserve. Numbers in the tables have been rounded.

Table 1: Mineral Resource Estimate as at 30 June 2021

Prominent Hill		Category	Tonnes	CuEq		Cu	Au	Ag	Cu	Au	Ag
			(Mt)	(%)1		(%)	(g/t)	(g/t)	(kt)	(koz)	(Moz)
Underground		Measured	42	1.6		1.3	0.6	3.2	520	830	4.3
$49/t NSR2 cut-off
	Indicated	44	1.5		0.9	0.9	2.7	420	1,200	3.9
envelope3
	Inferred	51	1.4		0.8	0.9	2.3	430	1,500	3.7
		Sub-Total	140	1.5		1.0	0.8	2.7	1,400	3,600	12
Surface Stocks - Copper4		Measured	2.4	0.8		0.6	0.4	1.7	14	28	0.1
Surface Stocks - Gold4		Indicated	9.5	0.5		0.1	0.6	0.4	10	190	0.1
Surface Stocks - Marginal4		Indicated	2.7	0.4		0.2	0.3	0.5	4.3	30	0.05
Surface Stocks4		Sub-Total	15	0.5		0.2	0.5	0.6	28	250	0.3
Total		Measured	44	1.6		1.2	0.6	3.1	540	860	4.4
		Indicated	56	1.3		0.8	0.8	2.2	430	1,500	4.1
		Inferred	51	1.4		0.8	0.9	2.3	430	1,500	3.7
		Total	150	1.4		0.9	0.8	2.5	1,400	3,800	12
Table 2: Ore Reserve Estimate as at 30 June 2021
Prominent Hill		Category	Tonnes	CuEq		Cu	Au	Ag	Cu	Au	Ag
			(Mt)	(%)1		(%)	(g/t)	(g/t)	(kt)	(koz)	(Moz)
Underground		Proved	25	1.7		1.3	0.6	3.2	320	490	2.6
		Probable	24	1.5		1.0	0.7	2.8	240	570	2.1
		Sub-Total	48	1.6		1.2	0.7	3.0	560	1,100	4.7
Surface Stocks - Copper4		Proved	2.4	0.8		0.6	0.4	1.7	14	28	0.1
Surface Stocks - Gold4		Probable	9.5	0.5		0.1	0.6	0.4	10	190	0.1
Surface Stocks - Marginal4		Probable	2.2	0.4		0.2	0.3	0.6	3.6	24	0.04
Surface Stocks4		Sub-Total	14	0.5		0.2	0.5	0.7	28	240	0.3
Total		Proved	27	1.6		1.2	0.6	3.1	330	510	2.7
		Probable	35	1.1		0.7	0.7	2.0	250	780	2.3
		Total	62	1.3		0.9	0.6	2.5	590	1,300	5.0

For the three months ending 30 June 2021, approximately 2.2 million tonnes of copper and gold ore was processed, 1.2 million tonnes from surface stockpiles and 1.0 million tonnes from the Prominent Hill Underground.

1. Copper equivalent (CuEq %) calculation can be found under "Cut-off parameters" in the attached JORC Table 1 documentation
2. Net smelter return (NSR) details can be found under Section 4 "Cut-off parameters" in the attached JORC Table 1
3. Envelope produced by stope optimisation using 5m minimum width, 12m height, 20m length
4. Stockpile cut-off is $17/t NSR which covers rehandle and processing costs

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Prominent Hill Mineral Resource and Ore Reserve Statement and Explanatory Notes As at 30 June 2021

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SETTING

Prominent Hill is an iron oxide copper gold (IOCG) deposit located in the Gawler Craton, South Australia (Figure 1). The Gawler Craton covers approximately 600,000 square kilometres of South Australia. The Gawler Craton hosts Olympic Dam, Prominent Hill, Carrapateena, and a number of other smaller and sub- economic copper-gold deposits. Most of these deposits are thought to be genetically related to the Gawler Range Volcanic (GRV) - Hiltaba magmatic event which affected the central and eastern portions of the Gawler Craton around 1600-1580 million years ago. Copper-gold-silver mineralisation at Prominent Hill is mostly hosted within hematite-matrix breccia. Copper mineralisation occurs as disseminations of chalcocite, bornite and chalcopyrite in the matrix of the breccia.

Figure 1: Location of Prominent Hill, South Australia

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Prominent Hill Mineral Resource and Ore Reserve Statement and Explanatory Notes As at 30 June 2021

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MINERAL RESOURCE

The Prominent Hill Mineral Resource as at 30 June 2021 has been estimated at 150 million tonnes grading 0.9 per cent copper and 0.8 grams per tonne gold (Table 1). This estimate includes mineralisation from both the Prominent Hill Underground and surface stockpiles. The Mineral Resource is inclusive of the Ore Reserve.

The updated Prominent Hill Mineral Resource estimate includes, where applicable, additional delineation and grade control drilling completed since the cut-off date of the previous Mineral Resource release, reflects geological interpretation adjustments and improved classification confidence, and mining depletion.

Changes in the Mineral Resource Estimate

Differences between the June 2021 and March 2021 Prominent Hill Mineral Resource estimates are summarised in Figure 2, Figure 3 and Figure 4. Differences include:

1. Data from 30 new drill holes have been added since the last estimate. Most of these new drill holes are located in zones of previously Inferred Mineral Resources. Consequently, a small proportion of the previously Inferred Mineral Resource has been reclassified as Indicated. Some changes have also been made to the geological interpretation within the remaining Inferred zone. Geological interpretation has not changed significantly in the Measured zone.

1. Decreases due to the depletion of existing surface stockpiles and ongoing mining of the underground Mineral Resource.

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Prominent Hill Mineral Resource and Ore Reserve Statement and Explanatory Notes As at 30 June 2021

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Figure 2: Tonnage change in 30 June 2021 Prominent Hill Mineral Resource estimate*

		June 2021 Mineral Resource Change
	160		Tonnage (Mt)
	150			2.9	150
	150
		-1.3	-0.9
Tonnes (Mt)	140
Mineralisation	130
120
	110
	100
	March 2021 Mineral Resource	Mining depletion	Stockpile change	Drilling and modelling changes	June 2021 Mineral Resource

*Totals subject to rounding to two significant figures. Data includes Measured, Indicated and Inferred Mineral Resources.

Figure 3: Copper metal change in 30 June 2021 Prominent Hill Mineral Resource estimate*

June 2021 Mineral Resource Change

1,450

Copper Metal (kt)

For

	1,400	1,400	14	1,400
			0.3
			-21
Copper Metal (kt)	1,350
1,300

1,250

1,200

March 2021 Mineral Resource

Mining depletion

Stockpile change

Drilling and modelling changes

June 2021 Mineral Resource

*Totals subject to rounding to two significant figures. Data includes Measured, Indicated and Inferred Mineral Resources.

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