Better known for red-cloaked Masai tribesmen and big game safaris, the United Republic of Tanzania is actually a phenomenally mineral-rich land.
Formerly known as British East Africa, and German East Africa before that, Tanzania came into being in 1964 upon the merger of Tanganyika, Zanzibar and the Pemba Islands. The country lies just south of the equator, on the east coast of Africa between the large lakes of the Rift Valley system and the Indian Ocean. It covers some 945,000 sq. km and is larger than the total area of France, Belgium, Germany and Switzerland, or slightly smaller than Texas and New Mexico combined.
Tanzania is a tropical country with climatic zones encompassing a humid coastal plain, a hot and dry rift area, a humid lake region, and temperate highlands. The estimated population of Tanzania is 27 million, fairly evenly divided between Muslims and Christians. Swahili is the official language of Tanzania, though English is widely used as well.
Long bypassed by the international mining industry because of its socialist policies, Tanzania changed course in the late 1980s, and it wasn’t long before foreign investment returned, not only in mining but in other sectors as well. Spared the turmoil and authoritarian regimes of many of its neighbours, Tanzania remains a relative oasis of peace, political stability, democracy, and regulatory transparency, particularly by African standards.
The country is well-served by international land, sea and air transportation routes. Aside from a few paved inter-city roads, poorly maintained dirt roads connect all towns and villages. There are also three major railway lines. Tanzania’s location on the Indian Ocean places it in an advantageous position for international shipping. Numerous airlines operate in and out Tanzania through two airports: Dar es Salaam and Kilimanjaro International, and several domestic airlines provide regular and reliable service.
Tanzanian mining law is embodied in the Mining Act, Government Notice No. 214, published in 1999. Licensing is based on a 3-tier system (not including small-scale licences that are only available to local artisanal miners):
n a reconnaissance prospecting licence grants exclusive rights for a period of 12 months;
n a prospecting licence grants exclusive rights for a period of three 3 years; and
n a mining licence can be granted for up to 25 years or more, depending on the estimated life of the prospective mine.
The geological framework of Tanzania reflects the geologic history of the African continent, beginning with the evolution of an Archean Shield through to the opening of that great chasm known as the East African Rift. The Archean rocks of Tanzania (more than 2.5 billion years old) consist of granite-greenstone belts, including the Nyanzian System, a series of typical Archean volcano-sedimentary sequences, or “greenstone” belts, within a much larger area of granite-gneiss complexes. The Nyanzian greenstones are of major economic importance, as they host most of Tanzania’s gold deposits. Almost all of Tanzania’s known kimberlites, diamondiferous or not, are also hosted in rocks of this system.
Tanzania’s gold potential is not even close to being well-explored, yet the country is already host to one giant gold deposit, and several more are known to host reserves approaching 1 million oz. or more. All are found in the aforementioned Archean rocks in an area south of Lake Victoria, and most appear to be associated with iron-rich lithologies in proximity to shear zones. The biggest is Bulyanhulu, owned by
Barrick has further established itself in Tanzania by taking over Pangea Goldfields, which has several projects in the country, including Golden Ridge, which is 30 km from Bulyanhulu. After acquiring the remaining half-interest in the project in early 1999, Barrick undertook an aggressive exploration program. Resources exceed 1.5 million oz.
Barrick, through Pangea, has a joint venture with
Based on ongoing projects and developing mines, Tanzania’s gold reserves are conservatively estimated at 25 million oz. Following the development of four gold mines, the country’s gold production doubled to 34 tonnes (more than 1 million oz.) in 2001, overtaking Zimbabwe as Africa’s fourth-largest producer. Tanzania’s first gold mine, Golden Pride, was officially opened in February 1999 and is wholly owned and operated by Australia’s
The Geita mine, jointly owned by
Australian-listed
Also active in the Siga Hills area is
Australian junior
Last but not least, Australian-listed
Rimming the Archean rocks to the east is a series of Proterozoic high-grade metamorphic rocks consisting of gneiss and minor mafic and ultramafic intrusions.
These rocks extend south from Kenya through Tanzania and all the way to Mozambique and host o
ne of the world’s greatest concentrations of coloured gemstone deposits. A dazzling array of gemstones of every colour and variety imaginable is on display. Sapphires and rubies — including a unique opaque variety of ruby, anyolite, found within pistachio-green zoisite — are found toward the north. A wide assortment of plum-to-mandarin-coloured garnets can be found at several locales, along with the unique and rare emerald-green variety known as tsavorite (originally discovered in Kenya).
Emerald and alexandrite are found near Lake Manyara, and the region also features zircon, tourmaline, amethyst, sphene and spodumene. In almost all cases, production comes both from independent small-scale miners and private Tanzanian companies.
Most famous, and totally unique to Tanzania, is the blue-purple variety of zoisite known as tanzanite, found exclusively in the Merelani Hills, near the city of Arusha. The region was formerly the scene of a mining rush, and today more than half of its production is under the control of Johannesburg-based
As if being host to numerous huge gold deposits and one of the world’s great coloured-gemstone belts was not enough, Tanzania also has the world’s largest diamondiferous kimberlite deposit. John Williamson, a Canadian geologist in the employ of
The Mwadui and adjacent New Alamasi diamond deposits occupy a former crater. Exceeding 1.5 sq. km, the crater was produced by the explosive eruption of a kimberlite about 50 million years ago.
Mwadui produced more than 13 million carats between 1940 and 1973, and is still in production. Mining of the surrounding black “mbuga” soils, gravels, and weathered tuff has yielded 17 million carats of diamonds since 1940. In its early years, grades reached as high as 107 carats per hundred tonnes (cpht). Today it is down to the 10-to-20-cpht range in the kimberlite, and 3 to 7 cpht in the surrounding placers.
Among the famous diamonds recovered from this giant deposit is a 54-carat pink diamond, which was cut into a 26.6 carat brooch and presented to then-Princess Elizabeth in 1947. Tanzania’s largest diamond, weighing 241 carats, was found at the Williamson mine in 1956. In October 2002, a 47-carat clean pink diamond was recovered from the open pit.
Curiously, the Mwadui pipe had no magnetic expression.
More than 300 kimberlite pipes are known across Tanzania, and about 20% are believed to be diamondiferous. All are found within the Archean Craton, mostly in clusters within a 200-km radius of Shinyanga. Despite Tanzania’s tremendous diamond potential, there are few domestic and no international mining companies exploring, aside from the typically secretive exploration activities of De Beers.
Hundreds of independent placer diamond miners and diamond buyers may be found scattered across north-central Tanzania, from Mwanza on the southern shores of Lake Victoria, to Shinyanga, just down the road from the Mwadui mine. All are engaged in the thriving, independent diamond trade, a model of free enterprise that brings significant wealth to countless African farmers and their families, and a host of independent diamond buyers from all over the world.
Sadly, most if not all, of these people will be put out of business as a result of the Kimberley Process, an ill-conceived and duplicitous set of regulations requiring that the origin of all diamonds be inspected and certified. Although large diamond producers are able to incorporate this bureaucracy into their mining and marketing process, the independents cannot. Of course, this suits the main diamond producers just fine, as it will eliminate more than 20% of global production and force consumers to come to them instead.
There are few countries around the world that can claim such a rich and diverse mineral endowment. The famous “big five” — lion, leopard, cheetah rhinoceros, and elephant — may be what have historically attracted people to Tanzania. However, today’s miners in Tanzania have their own big five: gold, diamond, ruby, alexandrite and tanzanite. Now that’s elephant country!
— The author is a certified gemologist and professional geologist. He is executive vice-president and exploration manager for Odyssey Resources, a Canadian junior active in Turkey and throughout the Mediterranean and Africa.
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