• Mining

Intrepid, enterprising Geological Survey

- 2023-08-29 00:00:00

Geological Survey of Namibia is the custodian of Namibia’s rich endowment of geological resources.
This according to Josephine Uushona, a senior geoscientist in the mines and energy ministry, who added that the department facilitates the responsible development and sustainable utilisation of these resources for the benefit of all Namibians.
The Geological Survey of Namibia became a directorate within the ministry shortly after independence. Initially, it consisted of three divisions, namely: Regional geoscience, applied geoscience and geotechnology.
Thereafter, several international collaboration projects were established under the leadership of Brian Garner Hoal as director from 1992 until 1996.
Restructuring in 2015 resulted in the conversion of the directorate into the department of geological survey, and two directorates were established known as the applied geoscience and the mapping and geo-information directorates.
The mapping and geo-information directorate consists of three divisions: Geophysics, geo-information and regional geoscience, while the applied geoscience directorate consist of economic geology, engineering and environment geology, and the geochemistry and laboratory division.
The geochemistry and laboratory division further has two subdivisions: Analytical geochemistry and regional geochemistry.
The analytical geochemistry division houses geochemical laboratories equipped with a wide range of modern facilities and instruments to provide analytical services to a wide range of clientele, Uushona said.
Meanwhile, the regional geochemistry division is tasked with the implementation of a countrywide regional geochemical sampling programme (RGSP), initiated in 2000, with the aim of establishing a national baseline geochemical database of elements in the anthropogenically undisturbed geosphere.
The geochemistry and the laboratory division employs 14 Namibians who run 17 laboratories, along with three geoscientists, two geo-technicians and three technical assistants falling under the analytical geochemistry subdivision.
Equipment on hand includes a vibratory disc mill, a disc mill and a planetary ball mill from Retsch, a Frantz isodynamic separator, a Wilfley table with vibratory equipment, an Osborn MMD Crusher and a 25-tonne hydraulic rock splitter. Ovens and a Carbolite gero furnace are ready for use as well as a Logitech CS-10 thin section cut off saw, a Covington engineering heavy duty slab saw and a Logitech GTST thin section cut off saw.
The Geological Survey laboratories also boast an IU30 vacuum impregnation unit, a PM2 precision polishing machine, a Felker Di-met small saw, one Dickie and Stocker hydraulic press DS-40 and since June 2006, also a Fusion machine.
They have an electromagnetic laboratory micro-pulveriser and sieve shaker, hot plates, an ultrasonic bath, Bruker X-ray diffraction, an Olympus BX53 microscope, a Schneider immersion microscope, a Schneider Refractometer, a Leitz wetzlar hardness tester, one Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), a Wavelength Dispersive X-Ray Fluorescence (WD-XRF) and an Atomic Absorption Spectrometer (AAS). The Niton X-ray fluorescence machine is portable.
Tests that can be done by the organisation include petrographic descriptions using optical microscopes and an in-built camera. Heavy mineral separation using the heavy liquids is done using the Wilfley table and Franz magnetic separator. Identification of polished gemstones by determining bulk specific gravity, refractive index and using microscopes and a polariscope is another possibility.
Sample preparation includes drying, splitting, crushing, milling, sieving and weighing. Chemical analysis of rocks, minerals and soils using the portable XRF technique is also a service available from Namibian Geological Survey.
Mineral identification using the X-Ray diffraction technique, thin section production, rock slabbing, core cutting and rock polishing are familiar busy-work at the institution. Most in demand are sample preparation services including crushing and milling, chemical analysis and mineral identification, according to the department.
The expand on its capabilities, it could make use of age-dating techniques such as lacer ablation ICP-MS for geochronological studies, while ICP-MS would be useful to analyse ultra-low concentrations in various sample media, including soil, water and rocks. Fire assay techniques for gold analysis would also be a welcome addition.
The organisation does face limited human resources to execute its essential mandate, and a lack of specialised skills to operate conventional instruments including AAS, ICP-OES and WD-XRF contribute to prolonged downtime of instruments due to delayed maintenance.
Nevertheless, recent achievements include the finalisation of its ‘Standards for Presenting Geochemical Data’ document, which is now used for producing geochemical maps.
Also, the Okahandja geochemical map production and interpretation for spatial distribution of copper, iron and arsenic, using portable XRF data, was completed for the first time in history, according to the geoscientist.
“We plan to finalise the sampling on the Warmbad map sheet and to commence with the low-density sampling orientation survey in the southern part of Namibia," Uushona said.
"We will ensure development of analytical methods for geochemical analysis on WD-XRF, ICP-OES and AAS, and to commence with trial geochemical analysis of stream sediments and soil samples from the Okahandja map sheet. We are also drafting a responsive laboratory quality manual with the respective standard operating procedures and working instructions,” she added.