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Sunday 18 August 2019
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Profiling Namibia’s mineral resources

Minerals galore in a starving State

 

phosphate-pic diamonds copperMinistry of Mines and Energy has full custodianship of all mineral resources in Namibia on behalf of its citizens. To this end, the ministry promotes and regulates the minerals and mining sector for transformation, growth and development as well as ensures that all Namibians derive sustainable benefits from the country’s mineral wealth.
Various specialised divisions of the ministry and institutions are responsible for the administration of the mining and regulations and for promoting the development of the industry. According to official information, by 1992 of the several 100 minerals present in Namibia, around 60 percent had already been exploited.

 

Diamond, uranium, copper and gold were among the largest sectors of Namibia’s mining industry in terms of employment, investment and revenue generation. Uranium and diamonds continue to play a major role in the mining sector while significant deposits of base metals have helped Namibia rank among the top five mining countries in Africa, both in terms of production and reserves. But despite Namibia’s rich mineral heritage, thousands of the country’s populace continue to wallow in abject poverty while only a few have access to the country’s natural resources. The unequal distributing of resources has been blamed for the high inequality within the Namibian society. However, although the mining sector is seen as a strategic sector for the country, no assessment of the country’s minerals has been done in the last 24 years.
Although outdated, the country’s latest resource book when it comes to minerals titled “The Mineral Resources of Namibia” – compiled in 1992 – gives a glimpse of the minerals deposited in several parts across the country.

Base metals

Chromium
At the time of assessment, no chromite was yet produced in Namibia and no deposits of commercial value were known. The metal base has, however, been observed to occur at various localities. It has been found in peridotites and dunites of Kunene mainly.

Cobalt-Nickel
Several areas hosting anomalous amounts of nickel and cobalt exist in Namibia. The main commercial nickel ore mineral is pentlandite, which occurs in association with mafic complexes. A variety of cobalt minerals have been identified from the hydrothermal Tsumeb pipe.
Copper
Copper is by far the most abundant mineral commodity in Namibia. This is reflected not only in the fact that there are several copper mines in the country, but official data reveals that Namibian copper deposits have been exploited for centuries. Radiocarbon dates suggest that copper has been smelted in the Khomas Hochland from as early as 1420, while pre-modern mining and metallurgical activities peaked during the 17th century. From 1908 to 1992, 1.6 million tonnes of copper were produced in Namibia.

Iron
Large reserves of low-grade iron ore and, in a few instances high grade ore, are present in Namibia. The known deposits have been grouped into two basic types: those associated with igneous and volcanic rocks and sedimentary deposits. The largest iron ore deposits in Namibia are sedimentary by nature, and these are described in order of the age of the rocks in which they occur.

Lead-Zinc
Namibia is the largest producer of lead and zinc on the African continent. The two commodities along with diamonds, uranium and copper, are the most important revenue earners in the local mining sector. Most of the lead-zinc deposits in Namibia, as well as all the major producing mines are located in central and southern Namibia.

Manganese

Namibia has various occurrences of generally minor manganese mineralisation. The main deposit, and the only one to have been productive is the Otjosondu manganese field.

Molybdenum
Molybdenum is found in small quantities in ore deposits such as porphyry, contact-metamorphic and pegmatitic and hydrothermal deposits. Three porphyry copper deposits with associated molybdenum mineralisation are situated in southern Namibia.
Tin

Tin was first discovered in Namibia in 1908. In the early days, tin was worked in sedimentary occurrences, although subsequently pegmatite mining became the more important producer. The tin deposits in Namibia occur mainly in the central parts. Prospecting and drilling of the ore bearing veins commenced in 1945.

Tungsten

Most of the tungsten mineralisation in the country is confined to the central part of the country but minor deposits do occur in the south along the Namibian-South African border.

Vanadium
Vanadium occurrences are fairly unevenly distributed. It occurs mainly as vanadates and was first discovered in the Tsumeb ore body in 1908.

Rare Metals

Arsenic
In Namibia, arsenic occurs in association with copper, lead and zinc ore to a much lesser extent with tin-bearing pegmatites and gold mineralisation. The only production is in the form of arsenic trioxide, which is a by-product of the base metal ores treated at the Tsumeb smelter. Arsenic is mainly found in the Otavi mainland, Tsumeb and Grootfontein districts.

Bismuth
Native bismuth and bismuth minerals are found in small, erratic bodies of muscovite greisen and in cleavelandite adjoining quartz-perthite cores of rare metal pegmatites. It has been produced from zoned pegmatites in the Tantalite Valley and Karibib areas. Other bismuth occurrences are hydrothermal, skam and greisen deposits. However, there has been no production from these types of occurrences.

Cadmium

The main occurrence of cadmium is in the Tsumeb body ore where it is a substitute for zinc in specific minerals. The presence of cadmium in phosphorites of the Namibian shelf constitutes a different type of cadmium occurrence.

Germanium-Gallium

The only mine in Namibia that has ever produced germanium is the Tsumeb mine. In the 1960s, TCL developed its own germanium reduction plant, prior to which overseas smelters extracted the germanium ore from lead concentrates. The tailings of the bulk-sulphide flotation circuit were treated with a magnetic separator to recover a germanium concentrate. Germanium dioxide was produced from the concentrate in the germanium reduction plant by complex leaching, evaporation, distillation and hydrolysis.

Niobium-Tantalum

The occurrences of niobium-tantalum mineralisation in Namibia are classified and described, according to their geographical age and type of mineralisation. It is found mainly in central Namibia.

Precious metals

Gold
Gold was discovered in Namibia during the early German colonial times in the Rehoboth district. The 1917 discovery of the Ondundu gold fields in the Omaruru district marked the first and only true Namibian gold rush. The commissioning and coming into production of the Navachab gold mine in the Karibib district in 1989 was a result of more upswing in gold exploration that started in the early 1980s.

Silver

Sliver produced in Namibia is derived from copper, lead and zinc ore deposits. A lesser amount is associated with gold, nickel and tin ores. The metal is recovered as a by-product of base metal ores. Native silver was first found associated with chalcocite in the upper oxidation zone.
Precious and semi-precious stones
Diamonds
Namibia is renowned for the quality and quantity of gem diamonds produced from the marine terrace gravels along the barren desert coast. Namibia’s diamonds are of high quality. They show little abrasion and the percentage of industrial stones is very low while more than 95% of all stones are of gem quality.

Semi-precious stones

Industrial minerals
Alunite

Alunite was found on the farm Gross Daberas 17 in the Keetmanshoop district. Alunite occurs along the weathered contact between a gypsum and capped-rich and a laminated yellow shale. Apart from Farm Gross Daberas, not other alunite occurrences have been recorded in Namibia, although geologists believe there are deposits in areas where exposures of the white hill shale formation occur.

Andalusite-Sillimanite-Kyanite
Various deposits of kyanite and sillimanite have been mined in Namibia. In general, mining ceased because of the discontinuous nature, small size and low grade of the ore bodies. In some cases, the cost of mining at depth proved to be prohibitive. No andalusite deposits have been mined. Andalusite is present in the Kuiseb formation in a zone trending southwest from Okahandja.

Antimony

Antimony is associated with copper ore bodies and some pegmatites in Namibia, however, the only economically exploitable occurrence is that associated with the copper-lead-zinc ore from the Tsumeb mine.

Asbestos

Ever since the introduction of rich asbestos deposits in South Africa and Zimbabwe prospectors have tried to locate asbestos in Namibia as well. Intensive prospecting started in 1928, the time of the great asbestos boom in SA. The first asbestos deposit in Namibia was discovered by a farmer in the 1920s on farm Kochena. Although asbestos occurrences have been discovered, no asbestos has ever been produced in Namibia.

Barite

Barite occurrences are scattered over most of the country. Deposits are located in Kaokoland, Damaraland, Outjo, Okahandja, Swakopmund, Windhoek, Rehoboth, Maltahohe, Namaland, Bethanie and Lüderitz districts.
Bentonite and Hectorite
Bentonite is a fine-grained clay 85% of which is composed of the smectite group of minerals.
Corundrum
There are only few known corundrum occurrences in Namibia. They are limited in size and have not been extensively exploited in the past.

Diatomite

Deposits of diatomite in Namibia have formed from marine and freshwater diatoms in both the offshore and onshore areas. Although the deposit on the Namibian shelf is quite extensive, there has been no production of diatomite so far.

Feldspar

Feldspar has been produced on a limited scale as a by-product of pegmatite mining in Namibia. Extensive production has, however, been prevented by the lack of domestic feldspar-consuming industries. The pegmatite mines are largely concentrated in the central part of the country.

Fluorite

Although fluorite is widely distributed in various types of deposits throughout Namibia, only a few have been exploited. These include replacement ore in carbonate rock associated with the Okorusu Alkaline complex, veins hosted by igneous, metamorphic and sedimentary rocks and the in-filling of a volcanic breccia pipe.

Graphite

There are two types of graphite occurrences in Namibia. One type if found in altered granite of the Namaqualand Metamorphic Complex, and has been mined, and the other occurs in schists and marbles of the Swakop Group, Damara Sequence. The only mine in Namibia which has produced graphite is situated in the Bethanie District.

Lithium-Beryllium-Cesium

The deposits of lithium, beryllium and cesium minerals in Namibia occur mainly in the Karibib-Usakos districts.

Nitrate

The central-southern part of Namibia has a climate similar to Chile, the world’s only nitrate producing country. Consequently, minor deposits of nitre are found in Namibia, but there has been no production of nitre yet.

Phosphate
In Namibia three types of phosphate deposit can be distinguished, these are classified as phosphates related to alkaline complexes and carbonite dykes, phosphates of biogenic sedimentary origin and guano deposits. In contrast to world production, of which 85% is derived from marine sedimentary deposits and 15% from apatite associated with igneous rocks, Namibia’s phosphate production is derived entirely from guano deposits.

Salt

Five types of salt occurrences can be distinguished in Namibia. These are salt formed by solar evaporation in coastal pans, fossil rock salt in coastal pans, salt in inland pans, brine aquifers and salt in sediments. During the German colonial period the state had the ownership rights over all salt pans and in 1914 the sole right to remove salt from the Otjivalunda pan was given to a certain Mr Stoker of Outjo.

Titanium

The only occurrence from which titanium has been mined was in the Erongo Region. Official records indicate that between 1936 and 1937 more than 71 tonnes of hand-sorted, 95% pure rutile concentrate was recovered.

Nuclear and fossil fuels

Uranium

The upswing in the uranium market in the 1970s led to extensive uranium exploration in Namibia. Several airborne radiometric surveys conducted by the Geological Survey led to the discovery of the several uranium deposits. This has led to the mushrooming of uranium mines in western Namibia.

Coal

Coal deposits in Namibia, as in neighbouring countries, are confined to the Ecca Group of the Karoo Sequence. Coal occurs below several hundred metres of overburden, exploration is carried out by drilling.

Other minerals include:
Hydrocarbons
Sepiolite
Wollastonite
Zirconium
Soda ash and Thenardite
Sulphur and Pyrite
Talc and Pyrophyllite
Garnet
Gypsum
Iceland Spar
Mica
Quartz
REE-Yttrium-Thorium

Profile compiled by The Patriot




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