ARCTURUS MINE

GEOLOGY PRESENTATION05 JUNE 2015

SIMBARASHE N MASENDEKEGEOLOGY STUDENT

ZIMBABWE SCHOOL OF MINE

Introduction

• Arcturus Mine is located 34km east of Harare.• Current mining activities are taking place in the following

sections:– Venus– Gladstone– Ceylon

• Gladstone is located 4km east of Arcturus.• Ceylon is located 8km east of Arcturus.

BRIEF HISTORY

1907 - Gold first produced from the Arcturus reef, followed by production from Slate, Planet, and Mafuta reefs. (Reserves were 213 000t @ 24-29g/t in 1913).

1920 – Closure of mine after running out of ore reserves. 1945 - LONRHO bought the mines under Corsyn Consolidated Mines. 1966- Discovery of Venus Ore-Body on 10 level. 1971 - Ceylon mine was bought. 1987 - Gladstone and Viceroy mines brought into the fold. 1997 - Lonmin operating as Independence Gold Mining took over from

Lonrho. Oct 2002 – Metallon Corporation Limited bought Independence Gold

Mining from Lonmin. Gold Production for Arcturus group up to September 2007:

46.683 tonnes (1.501 million oz)

REGIONAL SETTING

• Arcturus Mine is located (in the Enterprise belt) in the south-eastern limb of the Harare Greenstone Belt, roughly 2km from the granite-greenstone contact.

• The Harare Greenstone belt is surrounded by younger and intrusive granitoids-Chinamora, Chinyika tonalites, Chikwaka & Nyabira complexes

• The host rocks comprise a north-dipping sequence of metabasalt and ultramafics with intercalated felsites.

• Ore bodies occupy a broad zone (of varying width) of sheared and hydrothermally altered greenstone.

• All the ore bodies on all the mines typically form splays and in places en-echelon structures, a strong indication that they occupy shear zones.

• The shear zone can be traced intermittently for about 12km i.e from east of Ceylon Mine to Alpha Mine on Cromlet Farm.

REGIONAL GEOLOGICAL MAP

Reedbuck Prospect

Arcturus, Gladstone and Ceylon Corridor

Victor

Golden Shower

STRUCTURAL CONTROLS

• Two dominant structural trends host gold deposits in the Enterprise Belt.

1. NE trending fracture system, which is parallel to sub-parallel to the major NE trending Umwindsi Shear Zone (USZ), and to the regional structural trend.-this system hosts Victor, Fiona, Golden shower prospects.

2. E–SE trending fracture system that is oblique to the regional structural trend. -this hosts the major gold mineralisation i.e. Arcturus, Mafuta, Planet, Venus, Gladstone, Ceylon. About 98.7% of the gold produced from the Enterprise Belt was from structures parallel to sub-parallel to this fracture system.

Major Reefs at Arcturus

• There are 6 major reefs at Arcturus.• These are:

– Venus– Arcturus– West– Slate– Saturn– Planet

• See next slide.

Relative positions Of Major Reefs at Arcturus

Venus

• Ore bodies are irregularly – shaped, discontinuous and lenticular.• Reefs comprise well banded to laminated siliceous lithologies

that consist of millimetre to centimetre units of pink-brown, cherty layers of k-feldspar-quartz-biotite-arsenopyrite which alternate with amphibole – diopside – epidote – plagioclase units containing pyrrhotite and pyrite.

• Pyrrhotite and arsenopyrite are the dominant sulphides.• Free gold is rare.• The reefs are arranged in an en echelon array in the alteration

zone.• The ore bodies trend south-easterly and dip at 55 - 70 degrees to

the north-east.• The payshoots show variable pitch towards the west.• Ore body widths vary from less than a metre to 30 metres.

Venus – Dolerite Dyke

• The dolerite dyke (25 – 40m thick) dipping 60 degrees SW exists around 2 – 3 level.

• Ore bodies above the dyke were mined from surface.• The intrusion of the dyke resulted in a reverse movement

which subsequently resulted in a vertical displacement of 80 – 90m.

Gladstone • The ore bodies (0.2 – 1.5m wide) strike east-west and dip between 50-70

degrees to the north.• Gladstone reef channels appear to represent an extension of the Venus shear

zone.• There are 5 major reef systems, namely

– The Gladstone fissure - west of Ben Shaft: Short strike (up to 30m), lenticular quartz reefs.

– The Gladstone East Extension - east of Ben Shaft: Is almost on the same strike as the Gladstone Fissure; The reef is finely banded pinkish – brown siliceous unit with sulphide blebs.

– B.J. lode – lies 16m in the footwall of the Gladstone East Extension.– Buck Reef – in the footwall of the Gladstone Fissure.– Louise Grand – 900m ESE of Gladstone.

• A 17m thick dolerite sill with a southerly dip of 20 degrees was encountered in the upper levels (4 & 5 level)

Ceylon

• Ore bodies generally strike east-west, dip between 55 - 70 degrees north and vary in width from less than 1 metre to 5 metres.

• Occasional vertical, north-south striking reefs, e.g. the ‘Snake Reef’, cut the predominant east-west channel system to the west of the mine.

• Reefs pitch to the west.• The reefs are similar to those at Arcturus.• Mining of ore bodies on surface was initiated in June 2006.• Ceylon Pit operations were temporarily suspended in

February 2007.