COPPER PROSPECTS.
There are
many copper occurrences but most are small and low - grade. The more
important environments for these occurrences are associations with felsic
volcanic rocks in the Archaean greenstone belts. The literature contains
only scanty descriptions. Some of the more important examples are
mentioned below.
Kamba Hill Prospect.
Kamba
hill lies on the east bank of the Mara River in the Mara greenstone belt,
about 6.5 km south of the Old Mara Gold Mine.Copper occurs n the gold
bearing Kamba Reef, which follows the granite contact south of the East
Mara Gabbro complex. The average width is 2.2 m, with copper and gold
values ranging up to 2.3% and 8.5 g/t respectively. Copper occurs as
chalcopyrite and as chalcolite and oxides in the oxides zone.
Bulyanhulu Mine.
The mine
is a copper deposit with high gold values averaging 15 g/t, consists of
gold - silver - copper - bearing quartz - sulphide veins. The average
grade of copper is 0.52 % and silver is 11.4 g/t in mineable resource of
13.64 Mt. Barrick Corporation is now operating the resource as a gold mine
and producing copper as a by product. The average content annual
production of copper concentrate is 25,000 tonnes with 12% copper content.
Samena.
This pyrite - pyrrhotite body was discovered by the British Overseas
Geological Survey during a 1959 - 1963 mineral exploration programme. It
lies in the Geita greenstone belt, in intermediate to felsic lavas, with
lesser albitised tuffs and BIF. The sulphur content is 13 to 26%.
Resources are inferred to be in the order of 200 Mt. The potential for
copper mineralisation is favourable. Samena could represent a Cyprus -
type massive sulphide (Cox and Singer, 1986, mode 24a) or a related
massive sulphide type.
In 1998,
Tanganyika Gold carried out further exploration work and described the ore
body to have a 13:7 pyrite - pyrrhotite ratio and to contain minor copper,
lead, zinc and gold.
Nzega East Greenstone Belt Prospects.
No
economic occurrences of Zinc Mineralisation have been reported. The
potential is high particularly in the greenstone belts, which remain
relatively unprospected for base metals. Several prospects lie in the
eastern part of the Nzega greenstone belt, including Wela Hill, Wela
North, Manyavu, Mwamela and Ngulu Hills. Perhaps it is significant that
the Nzega greenstone belt contains a higher proportion of felsic volcanic
rocks than the more northerly greenstone belts. This belt includes a
package of BIF, Cherts and felsic volcanic rocks (some with developed
gossans) overlying basaltic volcanic rocks in what is probably the core of
an anticlinorium.
Several
gossan localities and geophysical anomalies located during the countrywide
airborne located during the countrywide airborne geophysical surveys were
drilled by the Minerals Division in the Nzega area in 1981 - 1982. Zinc
mineralisation was encountered in several drill holes, with intersections
reported as high as 4.6% zinc over 6.5 m. Ground geophysics and further
drilling might locate additional resources.