The Geita Greenstone Belt (GGB) hosts several world-class shear-hosted Archaean lode gold deposits and forms the northern portion of the regional Sukumaland Greenstone Belt, itself one of several belts that comprise the Lake Victoria Goldfields. Other gold mines hosted in the Lake Victoria Goldfields include Golden Pride, Bulyanhulu, Tulawaka, Buzwagi and North Mara.

The east-west oriented GGB is 60km in length, up to 15km wide. The Geita terrain is comprised of upper- to mid-Nyanzian greenschist facies units, made up of clastic sediments, black shales, banded iron formation (BIF) and volcaniclastics. These have been intruded by a variety of felsic to mafic intrusive bodies, dykes and sills. Regional north-northeasterly structures hosting Proterozoic gabbro dykes are also prominent geological features in the area.

North-west trending deformation corridors divide the GGB into three distinct sub-terrains, namely the Nyamulilima Terrain in the west (hosting the Star and Comet, Ridge 8 and Roberts deposits), the Central Terrain in the central part (hosting the Nyankanga, Geita Hill, Lone Cone and Chipaka deposits) and the Kukuluma Terrain to the north-east (hosting the Matandani, Kukuluma and Area 3 West deposits).

Geita’s gold mineralisation is preferentially hosted in BIF, cherts and ironstones that have been affected by both ductile and brittle deformation associated with shear zones. The shears exploit fold axial planes as well as the contacts ........

The Geita gold deposits are mined as a multiple open pit and underground operation, with ore production from Star and Comet, Nyankanga and Geita Hill underground mines, and from Nyamulilima open pit. The mine is currently serviced by a CIL processing plant with an annual capacity of 5.2Mt.

Geita has been an open pit mining operation from 1999, with underground operations commencing at Star and Comet in 2016, at Nyankanga in 2017 and at Geita Hill in 2020. Underground ore is now a significant part of the feed to the plant. The Nyankanga open pit was completed in late 2020, with the new Nyamulilima open pit commencing in April 2021, providing four sources of ore to the Geita processing plant.

Open pit mining is by conventional truck and shovel methods, where production mining equipment is operated by GGM with Capital Mining Services Tanzania Limited providing production and grade control drilling services, and Orica providing blasting and explosives services. Underground mining commenced at Star and Comet in 2016 and subsequently at Nyankanga in 2017 and most recently Geita Hill in 2020.

Star and Comet underground has successfully transitioned to owner mining and the mining contractor African Underground Mining Services is used at Nyankanga and Geita Hill for underground development and stoping. The underground mining method is a combination of LOS and TOS. Cemented aggregate fill backfill is used at Nyankanga to fill the primary stopes. Ore is ........

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