Geology: The Harmony Free State operations are located on the south-western corner of the Witwatersrand Basin, between the towns of Allanridge, Welkom, Theunissen and Virginia. The basin, situated on the Kaapvaal Craton, has been filled by a 6km thick succession of sedimentary rocks, which extends laterally for hundreds of kilometres.

The Free State goldfield is divided into two sections, cut by the north-south striking De Bron fault. This major structure has a downward vertical displacement of about 1 500m in the region of Bambanani, as well as a lateral shift of 4km. This lateral shift can allow a reconstruction of the orebodies of Unisel to the west of the De Bron and Merriespruit to the east. A number of other major faults (Stuirmanspan, Dagbreek, Arrarat and Eureka) lie parallel to the De Bron fault.

To the west of the De Bron, current operating mines are Target, Tshepong, Phakisa, Unisel, Bambanani and Joel. Dips of the reef are mostly towards the east, averaging 30 degrees but become steeper approaching the De Bron fault. To the east of the fault lies Masimong mine. These reefs mostly dip towards the west at 20 degrees, although Masimong is structurally complex and dips of up to 40 degrees have been measured. Between these two blocks lies the uplifted Horst block of West Rand Group sediments with no reef preserved.

The western margin area is bound by synclines and reverse thrust faults and is structurally complex. Towards the south and east, reefs sub-crop against overlying strata, eventually cutting out against the Karoo to the east of the lease area.

Most of the mineral resource tends to be concentrated in reef bands located on one or two distinct unconformities. A minority of the mineral resource is located on other unconformities. Mining that has taken place is mostly deep-level underground mining, exploiting the narrow, generally shallow dipping tabular reefs.

The Basal Reef is the most common reef horizon and is mined at all shafts except Target and Joel. It varies from a single pebble lag to channels of more than 2m thick. It is commonly overlain by shale, which thickens northwards. Tshepong has resorted to undercutting its mining panels to reduce the effect of shale dilution.

The second major reef is the Leader Reef, 15–20m above the Basal Reef. This is mostly mined at shafts to the south (Unisel). Further north, it becomes poorly developed with erratic grades. The reef consists of multiple conglomerate units, separated by thin quartzitic zones, often totalling up to 4m thick. A selected mining cut on the most economic horizon is often undertaken.

The B Reef is a highly channelised orebody located 140m stratigraphically above the Basal Reef. Because of its erratic nature, it has only been mined at Masimong and Tshepong. Within the channels, grades are excellent, but this reduces to almost nothing outside the channels. Consequently, both shafts have undertaken extensive exploration to locate these pay channels.

The A Reef is also a highly channelised reef, located some 40m above the B Reef. This was only mined at Harmony 2 and Brand, although an extensive channel lies along the western margin from Nyala to Lorraine. It consists of multiple conglomerate bands of up to 4m thick and a selected mining cut is usually required to optimise the orebody.

Joel mine, 30km south of Welkom, is the only Harmony Free State operation to mine the Beatrix Reef. This varies from a single-pebble lag to a multiple conglomerate, often showing mixing of the reef with some of the overlying lower-grade VS5 (mixed pebble conglomerate) material. None of the other reefs are present this far south, having sub-cropped against the Beatrix Reef.

The Target operations are at the northern extent of the Free State goldfields, some 20km north of Welkom. The reefs currently exploited are the Elsburg-Dreyerskuil conglomerates, which form a wedge-shaped stacked package, comprising 35 separate reef horizons, often separated by quartzite beds. The Elsburg Reefs are truncated by an unconformity surface at the base of the overlying Dreyerskuil member. Below the sub-crop, the Elsburg dips steeply to the east, with dips becoming progressively shallower down dip. Close to the sub-outcrop, the thickness of the intervening quartzites reduces, resulting in the Elsburg Reefs coalescing to form composite reef packages that are exploited by massive mining techniques at Target mine. The Dreyerskuil also consists of stacked reefs dipping shallowly to the east. These reefs tend to be less numerous, but more laterally extensive than the underlying Elsburg Reefs.

Gold – Mineral resources

	Measured resources								Indicated resources								Inferred resources								Total mineral resources
Operations	Tonnes   (Mt)		(g/t)		Gold   (000kg)		Gold   (000oz)		Tonnes   (Mt)		(g/t)		Gold   (000kg)		Gold   (000oz)		Tonnes   (Mt)		(g/t)		Gold   (000kg)		Gold   (000oz)		Tonnes   (Mt)		(g/t)		Gold   (000kg)		Gold   (000oz)
Under-ground
Bambanani	14.6		11.62		170		5 453		4.7		9.37		44		1 411		2.2		8.81		19		625		21.5		10.84		233		7 489
Joel	4.8		7.33		35		1 119		7.0		7.33		51		1 642		9.8		6.28		62		1 989		21.6		6.85		148		4 750
Masimong	10.4		7.81		81		2 610		5.4		6.89		37		1 198		74.2		6.02		446		14 352		90.0		6.28		565		18 160
Phakisa	1.9		11.17		21		687		21.0		10.87		228		7 336		28.1		7.83		220		7 073		51.0		9.21		470		15 096
Target
Target 1	8.2		7.92		65		2 087		12.8		7.80		100		3 212		5.1		6.49		33		1 072		26.1		7.58		198		6 371
Target 2	0.0		15.94		1		20		0.1		15.61		2		67		–		–		–		–		0.2		15.69		3		87
Target 3	11.0		8.45		93		2 987		9.0		7.81		71		2 268		4.7		5.37		25		816		24.8		7.63		189		6 071
Total	19.2		8.24		158		5 094		22.0		7.85		173		5 547		9.9		5.95		59		1 888		51.1		7.63		390		12 529
Freddies 9	3.4		9.56		33		1 046		3.0		9.17		28		893		30.4		6.65		202		6 493		36.8		7.12		262		8 432
Tshepong	12.9		10.58		136		4 379		10.4		10.45		108		3 478		11.4		11.96		136		4 372		34.6		11.00		380		12 229
Unisel	8.0		6.07		49		1 565		7.7		5.63		43		1 385		12.1		5.50		67		2 146		27.8		5.70		158		5 096
Total Free State under-ground	75.2		9.08		683		21 953		81.1		8.78		712		22 890		178.1		6.80		1 211		38 938		334.3		7.79		2 606		83 781
SA surface
Free State surface
Phoenix	110.4		0.28		30		980		–		–		–		–		–		–		–		–		110.4		0.28		30		980
St Helena	257.6		0.26		66		2 131		–		–		–		–		–		–		–		–		257.6		0.26		66		2 131
Other: Waste rock  dumps	–		–		–		–		6.8		0.53		4		115		31.1		0.45		14		454		37.9		0.47		18		569
Slimes dams	–		–		–		–		622.2		0.22		139		4 481		14.9		0.19		3		91		637.1		0.22		142		4 572
Subtotal	–		–		–		–		629.0		0.23		143		4 596		46.0		0.37		17		545		675.0		0.24		160		5 141
Total Free State surface	368.0		0.26		97		3 111		629.0		0.23		143		4 596		46.0		0.37		17		545		1 043.0		0.25		257		8 252
Grand total	443.1				780		25 064		710.1				855		27 486		224.1		–		1 228		39 483		1 377.3		–		2 863		92 033

Modifying factors

Underground operations		MCF (%)		SW (cm)		MW (cm)		PRF (%)		Surface operations		MCF (%)		PRF (%)
Bambanani		82		186		212		96		Free State (Phoenix)		100		48
Joel		86		153		183		95		Free State (St Helena)		100		45
Masimong		69		133		153		96		Free State (other)		100		53
Phakisa		84		110		139		96
Target 3		77		118		141		96
Tshepong		69		105		141		96
Unisel		75		179		191		96
Target 1		100						96

Gold – Mineral reserves

Uranium – Mineral resources

Modifying factors

	Operations		MCF (%)		PRF (%)
	Masimong		69		80
	Tshepong		69		80
	Phakisa		84		80

Uranium – Mineral reserves