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GEOLOGICAL SURVEY
OF NAMIBIA


Earth Sciences for Namibia's sustainable development

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Geochemistry Subdivision

The Geological Survey has an extensive laboratory complex. A range of facilities are available for the sample preparation and the determination of chemical, mineralogical and physical properties are summarised below:

Sample preparation:

- Splitting, crushing and pulverising of rock and mineral samples
- Sieving of unconsolidated material
- Mineral separation by heavy liquid media separation, magnetic
  separation and Wilfley table
- Slabbing and polishing of specimens (rock saws and lapping plates)
- Preparation of thin sections and polished sections using a Logitech
- Preparation of ultra-pure deionised water and acids in dual
  sub-boiling quartz glass still.
- Sample dissolution (lithium tetraborate fusion or by HF/HNO3 attack
  in teflon bomb)
- Weighing (5 figure balance)
- Preparation of pressed powder pellets for XRF analysis
- Preparation of fusion discs for XRF analysis

Analysis:

- Mineral identification by x-ray diffraction (XRD) and optical
  microscopy
- Spectrophotometer for the more accurate identification of ore
  minerals in polished section
- Investigation of fluid inclusion properties
- Moisture content and loss on ignition (ovens and furnaces)
- Determination of major and minor elements by XRF and ICP-AES.

In addition to these facilities the Laboratory complex also houses two specialist laboratories, one for the testing of Industrial Minerals and another for engineering geological tests.

The sub-division handles enquiries from a variety of sources, including general public and the Namibian Police and Custom, giving advice on rock and mineral identification and sample assay. Tin- and Tantalum-bearing concentrates are routinely analysed for the Small Miners Assistance Center, forming a part of their efforts to improve the socio-economic climate of the Uis area.

Last year the GSN took delivery of a Philips 2404 X-Ray Fluorescence (XRF) Spectrometer. This instrument, together with automatic fusion and palletising sample preparation apparatus, comprise a major capital development project (N$1.5m) funded by the Namibian Government. The XRF will enable the GSN to produce high quality major and trace element data on a variety of geological materials for program within the Ministry of Mines and Energy, as well as for the private sector.  xrf1.jpg 10 kb
Mineral identification is an essential requirement for the GSN, particularly for the testing and evaluation of industrial minerals. Replacement of the GSN's ageing X-Ray diffractometer was made possible through SYSMIN funds in an extension to the Industrial Minerals Project.  The equipment is now fully installed and functional.

Progress on pilot studies for regional geochemical surveys has been rather disappointing. These surveys are a new endeavour at the Geological Survey and are labour intensive. Unfortunately, in the present economic climate the GSN is unable to recruit the personnel required to carry out the sampling needed. Efforts have been made to secure funding to contract-out sample collection, but at this time it is not known whether these have been successful.

Capture of older archive data on open file is, however, ongoing. Manipulation of these data and the generation of maps have been greatly assisted by training under the auspices of the GEODESA Project.

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Last updated on 01 December 2004
Published by the Geological Survey of Namibia, Windhoek, Namibia
Copyright Geological Survey of Namibia 1997, 1998, 1999, 2000

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Phone: +264 61 2848111  Fax: +264 61 249144