Arcturus is situated (in the Enterprise belt) in the southern limb of the Harare Greenstone Belt. Orebodies generally comprise individual lenses which range from 0.2 m to 5.0 m in width and dip from 55° to 70°.
The Arcturus gold mine, located within the Shamvaian Group, is hosted in the Iron Mask Formation, which comprises a succession of metamorphosed felsic volcanics and associated metasediments including prominent bands of sulphide-facies iron formation, phyllites, meta-arenites, and quartzose schists (Oberthur et al., 2000). The mineralized shear zones in the Arcturus mine are characterized by silicification, biotite, and K-feldspar alteration. Gold mineralization is associated with pyrrhotite, arsenopyrite, and also occurs as free gold, which contributed up to 10% of production.
There are 6 major reefs at Arcturus: Venus, Arcturus, West, Slate, Saturn, Planet.
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 ........