Glassmaking raw material resources in Namibia
In accordance with the discussion held by His Excellency Dr. Sam Nujoma, President of the Republic of Namibia and the Government of the Czech Republic in 1999, the two governments agreed to cooperate in the field of geological survey and a promotion of building up glass industry in Namibia. The follow-on project „Evaluation of selected glassmaking raw material resources in Namibia“ was carried out by a team of specialists from the Czech Geological Survey, Sklopísek Střeleč Ltd., EXIMOS, ÚNS - Výzkum Company, Ltd., Kutná Hora and Brita Trade Company, Ltd., Hradec Králové.The major objectives of the project were to carry out a geological assessment of known quartz and other raw materials necessary for the glass-batch preparation in Namibia and realization of test meltings. However, an assessment of all known occurrences of vein quartz, pegmatite quartz, and aeolian sands in Namibia was negative either of insuffi cient reserves or low quality of quartz. During the 2001 field campaign, a new promising deposit of hydrothermal quartz was discovered approximately 40 km west of Rehoboth (Choaberib Farm). The deposit comprises four distinct vein-like bodies and another fi ve quartz blows 10 m or more in thickness. Seven individual outcrops can be traced on the surface for a distance of more than 200 m. The total economic reserves of 9.7 million tons of commonly massive milky vein quartz were calculated down to the depth of 25 meters. Samples after electromagnetic beneficiation showed slightly increased contents of Co (6–9 ppm).
A new large deposit of metasandstone was discovered at the vicinity of Rehoboth formed by sheet-like bodies. Total inferred reserves of all quartzite bodies (> 20 m thick) can be estimated at 6,8 mil. tons (99.26 wt. % SiO2, 0.4 wt. % Al2O3, 0.035 wt. % Fe2O3, and 0.03 wt. % TiO2).
Carbonate raw materials for glass industry were assessed in five regions of Namibia. White dolomite marbles from the White Rhino Quarry and from the Otjiwarongo quarry were found to be the most suitable – the waste and unsaleable blocks can be used. The dolomite marble from the Okongava deposit can be considered a suitable material for the production of colourless sheet/fl oat glass and colourless or container glass.
The test meltings of siliceous material from the Choaberib locality together with dolomite marble from the White Rhino deposit revealed that the materials are suitable for the production of high-quality colour parison (low-cost coloured crystal glass and high-lead crystal glass). The experimental production of blue decorative glass was also successfully realized at Kras Glass Ltd, Nový Bor. The hydrothermal quartz from the Choaberib Farm was recommended to the Namibian Ministry of Mines and Mineral Development to consider a small-scale manufacture of decorative glass at this locality.The experiments confirmed that the metasandstone from Rehoboth together with Okongawa dolomite marble are suitable for the production of coloured container glass (green-coloured glass for wine bottles, brown-coloured glass for beer bottles). The Goverment of Namibia instructed Geological Survey of Namibia and the Ministry of Trade and Industry to carry out a feasibility study for the establishment of a small glass factory in Rehoboth to produce container glass.
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