Within the Birimian and Tarkwaian lithologies of Ghana there are three major types of gold mineralisation:
Type 1: Reef, Vein or Lode gold deposits associated with regional scaled shear zones, such as the Obuasi gold mine to the north of Kubi.
Type 2: Granitoid-hosted, mesothermal gold mineralisation, such as Ayanfuri gold mine to the south west of Kubi.
Type 3: Auriferous quartz-pebble conglomerate deposits such as at Tarkwa and recent alluvial gold concentrations.

The Kubi deposit mineralisation style is Type 1: Birimian aged, shear hosted, reef, vein or lode gold deposit.

Mineralisation
The mineralisation occurs in a 1.0 to 15.0 metre thick garnetiferous horizon within Birimian metasediments. This garnetiferous horizon contains fine grained gold associated with minor (5-15%) pyrite, arsenopyrite and pyrrhotite as well as some coarser gold which is associated with relatively narrow quartz veins. Some mineralisation occurs in quartz veins and veinlets that cross-cut the Birimian-Tarkwaian contact, outside of the main garnetiferous horizon.

SEM (scanning electron microscope) and polished section studies have observed gold and associated sulphides such as pyrrhotite, pyrite, arsenopyrite and occasionally chalcopyrite, rimming and often replacing the included garnet blasts. The garnets are often highly tectonised with native gold, often coarse, and with sulphides coating the micro-fractures.

The grades exhibit ........

Previous mining at Kubi was by open pit mining methods. The Kubi Gold Mine open pit was operated by Ashanti Goldfields and AngloGold Ashanti in two phases between 1999 and 2007.

Previous underground mining study work includes only a report on the preliminary development to establish an underground drilling platform from which to conduct further geological exploration. The mining method was not discussed in the report. Mining methods that could be considered at the PEA level of study include:
- Shrinkage stoping
- Long hole open stoping
- Alimak stoping
- Drift and fill.

The unavailability of tailings backfill, since the ROM will be treated off-site, negates the use of drift and fill. Alimak stoping is not favoured due to the capital requirements for specialist mining equipment and specialist skills required for this method. Considering the methods listed above the two methods which are most suited to this body are shrinkage stoping and long hole open stoping.

An analysis of the vein widths was undertaken which showed that the average vein width is 3.5m. 80% of the mineralised tonnage is contained in veins with a width of greater than 2.0m. While shrinkage stoping works well in narrow stoping widths of 2.0m and less, it is not ideal for wider bodies as it requires men to work under the overhand face, which when stope widths are wider, presents a risk of injury due to falling rocks. Shrinkage stoping also results in a lar ........

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