Introduction.

Greenstones and gold prospects occur over a broad area, concentrated around the Iramba Plateau (Fig.33). The plateau is well watered and rises to an elevation of about 1,200 m. It is bounded by rift faults on three sides. Gold was discovered here during the German colonial period. Total production is reported to be 4,698.2 kg with 4,370 kg of this coming from the Sekenke Mine. Since early 1990s, there has been a large number of small scale miners in the area. Anmercosa Exploration Tanzania Limited conducted exploration work between 1996 and 1998. During this period, trenching, helicopter - borne magnetic, radiometric surveys and drilling programmes were conducted. Gold assay values in samples collected from Makaya, Missu,Binyoro, Wembwe, Sekenke and Kirondatal revealed that there is potential for gold mining.

The assay values range from less than 1 g/t gold to more than 15 g/t gold in the mineralisation.

Geology.

The oldest rocks in the Iramba Sekenke greenstone belt are the metavolcanic and metasedimentary rocks. These rocks are intruded by a porphyritic microcline - granite, which commonly exhibits hybridization phenomena at its borders. In the vicinity of Sekenke, a band of quartz - diorite separates the granite from the volcanic rocks. The volcanic series is mainly altered basalts and dolerites, that occur mainly in the western and central part of the area.

The majority of the gold deposits lie in the Volcanic series near the granitic contacts. Acid and basic dykes of many types cut the area. It has also been much faulted and sheared, with extensive intrusion of granites and fracturing by Cenozoic Rift Valley faults related to the East African Rift Valley system. However, it is believed that the main tectonic movement took place at a much earlier date.

Mineralisation.

Most of the gold deposits are in quartz veins within fractures and shears. A few cases are known which gold mineralisation appears to be controlled by stratigraphy of the enclosing metasedimentary rocks, but none have been found so far of ore grade. Numerous quartz reefs have been located within the shear zone. About 3 km of gold bearing reefs have been identified in the area. Mineralisation is largely confined to narrow pyretic quartz lodes. The country rock shows little gold mineralisation. Geological mapping and soil sampling carried out in the area identified a gold anomaly measuring 2 km wide and 4 km long.

In the past, Sekenke and Kirondatal were the only mines which achieved significant production. Both deposits occur in steeply dipping vein structures. Grades generally are high and it seems unlikely from the records of surface work that the areas surrounding the mines were ever fully prospected. There is no record of diamond drilling around the two mines, but some holes were drilled for extensions of the veins. Both mines extended to depths below the oxidation zone and were stopped at values of interest (to the present investor) in primary mineralisation.The other mines are all shallow with little reported production. At the kisimamba prospect, small amounts of gold were recovered from what is described as a quartzite, but what is probably a low - iron content BIF. This prospect was drilled by the Geological Survey with disappointing results.

The iramba - sekenke area is attractive because of its demonstrated ability to support small tonnage mining operations on high - grade vein deposits. Opportunities for discovery of deposits suitable for bulk mining and heap leaching technology have yet to be identified.

Old Sekenke Mine.

The Old Sekenke Mine was discovered in 1907 and worked from 1909 to 1959, at an average gold grade of 15.4 g/t gold and 2.5 g/t of silver. Several parallel quartz veins contain gold values of interest close to the contact between greenstone and diorite.

Economic mineralisation has widths of 0.5 to 2.5 m. Mineralisation was detected along a strike of 2.6 km, but mining was confined to a much shorter length. The veins occupy shears, which strike northwest and dip steeply.

Intersections in diamond drill holes below the old mine returned values of 19.7 and 2.9 g/t gold, respectively, over 2.9 m in two veins at a depth of 335 m and 25.5 and 28.7 g/t gold, respectively, over 2.2 m containing the same two veins at 244 m depth. Surface trenching by STAMICO between 1975 and 1977 found ore grade values in three separate veins. The tailings dump here contains an estimated 200,400 tonnes of material averaging 2 g/t gold which might be of interest to a small scale operator.

Kirondatal.

The old kirondatal Mine is said to have been exploited by Arab Traders in precolonial times. From 1939 to 1950, it produced 23,150 tonnes of ore which yielded an average gold grade of 8.9 g/t gold. Ore was at the intersection of shear with dykes of quartz - albite rock intruding greenstones.Several ore shoots were developed. The deepest shaft reaches a depth of only 40 m. Even at this shallow depth, the workings seems to have penetrated the base of the zone of oxidation as sulphide minerals (Pyrite,pyrrhotite and aresonopyrite) are mentioned in the descriptions of the ore. Altogether 13 veins have been mined to a greater or lesser extent.

Opportunities.

Currently activities in the area include gold mining by small - scale miners and exploration activities by Barrick Exploration Limited around the Old Sekenke and Kirondatal Mines. Exploration work conducted in the area includes helicopter - borne magnetic, radiometric surveys, drilling, geochemical surveys, drilling, geochemical surveys and trenching. The data obtained indicate that the area has a high potential for gold mining. Work is in progress to confirm some of the already obtained results.