The services offered include:
Sample Preparation
These include, but not limited to, weighing, screening, splitting, crushing, pulverizing, rock and core cutting,
polishing of rock slabs, preparation of thin sections, heavy mineral separation, acid digestion, preparation of
pressed powder pellets and fusion glass beads, and ashing/burning tests of some geological material.
Geochemical Analysis & Mineral Identification
Instrumentation techniques used require sample digestion with acids (e.g.
ICP-OES and
AAS) while others
are less destructive by analysing solid samples (e.g.
XRF and
XRD).
Optical polarizing microscopes and binocular microscopes, some of which are fitted with cameras are used for
petrographic studies. Specialized gemmological instruments are available for identification and evaluation of gemstones.
Atomic Absorption Spectrometry (AAS)
The AAS lab is equipped with the Analytik Jena ZEEnit 700,
a compact spectrophotometer providing Flame AAS, Graphite Furnace AAS and Hydride AAS.
Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)
The ICP lab is equipped with the PerkinElmer Optima 7300 DV
Spectrometer, which is used for multi-element analysis at varying concentrations (major oxides to trace elements).
X-Ray Fluorescence (XRF)
The Geochemistry labs are equipped with both the wavelength dispersive XRF (WD-XRF) and the energy dispersive XRF
(ED-XRF) techniques.
The WD-XRF is a Bruker S8 Tiger. For the ED-XRF technique, two hand-held NITON
XRF are available and these are routinely used for semi-quantitative analysis of rock specimen or powdered samples.
X-Ray Diffractometer (XRD)
The XRD lab is equipped with a Bruker AXS D8 Advance which is used for accurate identification of minerals.
ANALYTICAL GEOCHEMISTRY Sub-Division
The services offered include:
Sample Preparation
- Sample preparation is the process by which the samples are readied for analysis. Some of the Geochemistry labs
provide exploration clients and researchers with dedicated sample preparation facilities. These include, but not
limited to, weighing, screening, splitting, crushing, pulverizing, rock and core cutting, polishing of rock slabs, preparation
of thin sections, heavy mineral separation, acid digestion, preparation of pressed powder pellets and fusion glass beads,
and ashing/burning tests of some geological material.
- The choice of sample preparation method depend on the type of sample and the selected analytical technique. Good sample
preparation practice is essential to obtaining meaningful and reliable results.
- One critical issue which can never be avoided during sample preparation is sample contamination. There are many stages of
this process where sample contamination can occur. For example, the choice of crushing or grinding equipment used may
contaminate the sample. The level of contamination depends on the sample hardness, crushing and grinding times as well as
crushing/grinding media. However, to minimize levels of contamination during sample preparation, carefully selected crushing
and grinding tools with very little contamination levels are used (e.g. agate grinding vessels).
Geochemical Analysis & Mineral Identification
- Geochemical Analysis and mineralogical services are accomplished with the use of some of the most sophisticated analytical
instruments. A variety of approaches can be used, depending on the customer’s needs. Some of the instrumentation
techniques used require sample digestion with acids (e.g. ICP-OES and AAS) while others are less destructive
by analysing solid samples (e.g. XRF and XRD).
- Calibrations of these instruments are based on the analysis of international standard reference materials.
- In addition, other available instruments include, optical polarizing microscopes and binocular microscopes, some of
which are fitted with cameras are used for petrographic studies. Specialized gemmological instruments are available for
identification and evaluation of gemstones.
Atomic Absorption Spectrometry (AAS)
The AAS lab is equipped with the Analytik Jena ZEEnit 700,
a compact spectrophotometer providing Flame AAS, Graphite Furnace AAS and Hydride AAS. The choice of digestion method depends
on the elements of interest.
Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)
The ICP lab is equipped with the PerkinElmer Optima 7300 DV
Spectrometer, which is used for multi-element analysis at varying concentrations (major oxides to trace elements). Various
sample digestion methods are applied depending on the elements of interest.
X-Ray Fluorescence (XRF)
- The Geochemistry labs are equipped with both the wavelength dispersive XRF (WD-XRF) and the energy dispersive XRF (ED-XRF) techniques.
- The WD-XRF is a Bruker S8 Tiger, used to analyse for a wide-range of elements at varying concentrations (major oxides to trace elements).
Fusion and pressed pellet are the two standard sample preparation methods for this technique. Fusion involves melting the sample with
Borate flux and casting into a glass disc (platinum ware is used for this purpose). Pressed pellets are produced by pressing a mixture
of sample powder with wax at 30 tons with a hydraulic press.
- For the ED-XRF technique, two hand-held NITON XRF are available and these are routinely used for semi-quantitative analysis of
rock specimen or powdered samples. These can be used both in the laboratory and in the field.
X-Ray Diffractometer (XRD)
The XRD lab is equipped with a Bruker AXS D8 Advance which is used for accurate identification of minerals. A wide range
of minerals (including gemstones and clay minerals) can be identified using this technique. Sample preparation involves
grinding of a few representative grains of a sample for specific mineral identification.
REGIONAL GEOCHEMISTRY Sub-Division
- The Regional Geochemistry Subdivision focuses on the country-wide baseline geochemical sampling programme that commenced
in 2000. The Regional Geochemical Surveying Project (RGSP) is envisaged to generate valuable information with respect to
potential economic deposits, land use planning, environmental monitoring, pollution control and many other applications
suitable for the end-users’ needs.
- The activities for this subdivision include survey design, sample collection and monitoring of the sampling process,
sample preparation, sample analysis, samples and data archiving, as well as geochemical data interpretation, map and report production.
- The sampling survey is planned and done per one map sheet (1:250 000 scale)
at a time, selected on the basis of availability of existing data such as topographic maps, geological maps, high resolution
airborne geophysical surveys, known mineralization of economic potential, and perceived socio-economic-ecologic interest in the area.
- Sampling is usually carried out by contractors who are qualified geoscientists appointed through a Tender Process.
Sample sites are selected by the GSN staff at a sampling density of about 1 sample per 10 square kilometres, and samples
are collected as soil or stream sediment samples, depending on the topography of the area.
- Great care is taken to ensure that representative samples are collected from each site and are free of
contamination through human and animal activities. The sampling procedure used is based on the recommendations
from the final report of the IGCP Project 259 (“A global geochemical database”).
- Great care is taken to ensure that representative samples are collected from each site and are free of
contamination through human and animal activities. The sampling procedure used is based on the recommendations
from the final report of the IGCP Project 259 (“A global geochemical database”).
- Collected samples are properly catalogued and stored the Geological Survey Core-storage Facility. Those that are selected
for analysis are processed by milling with the Planetary Agate Ball Mill, then digested with acids for analysis with ICP-OES
or pressed into powder pellets and fused beads for analysis with the WD-XRF.
