Journey Around Tanzania

Major Regions in Tanzania

4. Mwadui-Mwanza-Musoma Region

Spatial Location of Mwadui Region in Tanzania

About 160 kilometers southeast of Mwanza, in the northern region of Tanzania, are to be found the Mwadui diamond mines near Shinyanga. On the other hand, Musoma is located about 160 kilometres northeast of Mwanza.  The Mwadui-Mwanza-Musoma Region is historically Tanzania’s major cotton growing area. Mwadui is the site of Tanzania’s most important mineral deposit – kimberlite rock, which contains diamonds. The nature of the terrain around the mines is completely flat except for one or two small hills. It is part of a great plateau, made of crystalline rocks, which stretches across most of central Tanzania. This plateau has an average height of between 3,800 feet (1,160 metres) and 4,000 feet (1,220 metres).  Of course, this plateau is not perfectly flat. For instance, in the north east there are several hills, one which reaches 4,540’ (1,383 metres). Conversely, in the wide, shallow valleys, created mainly by river action, the land falls to below 3,600 ft. (1,097 metres) as you head further southwest of the area.

Further north, the scenery around the Mwanza-Musoma section of the Lake Plateau is rather different. The plateau is no longer flat but dissected. Heavier rainfall has made the rivers which flow into Lake Victoria very powerful agents. These rivers have eroded the plateau into flat topped hills separated by wide and, sometimes, marshy valleys. In many ways the landscape is very similar to that found around Buganda, Uganda and Nyanza in Kenya. The climate of the Mwadui-Mwanza-Musoma Region, which is about 320 kilometres long, with one end found near the very large lake, while the other is located far from any source of moisture, has considerable variations especially with the rainfall. Mwanza has one wet and one dry season. The rainy season is continuous from October to May, with a much drier season during the months between June and September. In other words, the second dry season of December and January, which is found in those parts of East Africa set nearer the Equator, is missing. Mwanza has a climate that is more tropical than equatorial. There are still some equatorial influences since within the eight months long wet season there are two periods of heavier than average rainfall. March-April and November-December are these two wetter periods. It therefore suffices to say that Mwanza has a tropical climate with one dry and one wet season, but within the wet season there still exists two periods when the rainfall is particularly abundant.

Cotton Farming around Musoma

“Cotton is Tanzania’s second largest export crop after coffee and Africa’s fourth-largest producer of cotton after Mali, Burkina Faso and Egypt. About 14 million people or 40% of the total population derives their living directly or indirectly from cotton that is grown by an estimated 500,000 small holder farmers with approximate cultivated area of 400,000 hand crop of 360,000 tons and having a high potential for growth through sustainable farm management, contract farming, credit facility, adequate and efficient provision of farm inputs, etc. Presently, 70% – 80% of Tanzania’s annual cotton production is exported” – METL Group. Cotton is grown by the local farmers as their main cash crop; usually the farms are small, only 2 or 3 hectares in size.  Often these farms are fragmented – this means that the fields owned by one farmer are not found together, but are distributed over a wide area. On the larger modern farms which are highly mechanized, cotton is grown in a slightly different method from that of the small farmers. Some of the larger farms are found near Kibara, on the shores of Lake Victoria, about half way between Musoma and Mwanza. Overall, cotton in Tanzania is sold through well organized cooperatives, mainly between June and July. The ploughing is done in November and December; the cotton seeds being planted at the end of December. During March and April the cotton is weeded and by May the crop is ready for picking. From here, cotton is then graded based on lint to whether it’s white (healthy) or coloured (diseased).

Williamson Diamond Mines at Mwadui

Located a few kilometres north west of Shinyanga, the Williamson Diamond Mines is relatively large, partly because the outcrop of diamond bearing rock is probably one of the largest in the world. Millions of years ago a volcano was formed at Mwadui. The molten volcanic rock came up from inside the earth through a volcanic pipe. Eventually the molten rock in the pipe became solid and formed a volcanic plug. Since then the volcano has gradually been eroded away until all that is now left is part of the volcanic plug. It is this plug, made of a rare rock called kimberlite, which contains diamonds. Because the plug is at the surface there is no need for tunnels and shafts; instead the rock is simply dug out from the surface by mechanical shovels. A series of benches are dug, each about 8 metres high. The top bench is made of surface material like black cotton and the lower benches are made of kimberlite rock. Mining has been going on for nearly 80 years, beginning in 1940, so that lowest benches are now about 75 metres below the original ground level. Sometimes the rock is so hard that it must be broken up by explosives before the heavy machinery can dig it.

Heavy diesel lorries transport the ore from the benches to a crushing station, located near the benches, where the rocks are broken up until they are less than 100 mm in diameter. These small rocks are loaded into a long conveyor belt to the treatment plant, which uses advanced methods to remove the diamonds from the ore. After scrubbing, cleaning and sizing, the ore is passed through heavy media separators, where heavy diamonds and a few other heavy minerals sink to the bottom. The lighter materials float and can be removed. 98% of the waste rock is removed by the separators. The heavy minerals and diamonds are now milled with steel balls. Diamonds are the hardest of all minerals and are not affected, but the movement of the steel balls reduces the softer minerals to pulp. The coarse material are made wet and are placed on endless belts, which are covered in a layer of grease. The minerals roll off the grease because they are wet, but the diamonds are water repellent and therefore stick to the grease. The fine particles are passed between positive and negative electrodes, the diamonds which are very poor conductors of electricity being split away from the waste material. It takes ten million kilograms of ore to get half a kilogram of diamonds! The mine and treatment plants are situated far from centres of population and so the Williamson Diamond Company has built its own town, Mwadui, which has a population of about 23,300. Almost all the diamonds are exported, and diamonds are among Tanzania’s top-ten most important export.

Williamson Diamond Mines in Mwadui, Tanzania
Williamson Diamond Mines. Image Courtesy of The Citizen