Surface Exploration GeoChemistry
Surface exploration necessitates careful sample handling and meticulous analysis, to ensure that small anomalies are discriminated and contamination is avoided. LabWest specialises in these areas and can assist you in determining the best approach for your samples.
GOLD EXPLORATION GEOCHEMISTRY
Our techniques for detection of gold are optimised for surface and near-surface exploration, where anomalies can be very small, and signal discrimination is paramount.
Processes are designed to minimise the possibility of contamination, from barren-washing of pulveriser bowls during sample preparation through to use of disposable vessels for all stages of digestion and analysis.
Current-generation ICP-mass spectrometry (ICPMS) is used for elemental determination, yielding reliable sub-part per billion detection limits.
Separation and collection of ultrafine (< 2 µm) fraction from soil samples. Analysis of 40-element suite on the fine fraction, plus pH, salinity (conductivity), particle size distribution, and clay mineralogy (ASD).
LabWest Code UFF+: Collection and analysis of <2µm fraction for all UFF+ parameters.
Microwave Assisted Aqua-Regia Leach
LabWest has developed microwave-assisted digestion techniques to obtain maximum recovery of metals from geochemical samples, with negligible loss of volatiles and no cross-contamination.
Our microwave-assisted aqua-regia digestion (scheme code MAR) is a first-class exploration tool, giving a degree of confidence in results that is not easily obtainable with traditional hotplate or hotbox techniques.
Very low detection limits are obtained with current-generation ICP-MS. Although this is an aggressive digestion, complete recovery of resistate and silicate-hosted minerals cannot be guaranteed from any aqua-regia digest.
LabWest Code MAR-04 (50 elements)
Oxidised surface materials such as stream sediments containing free gold, are well suited to cyanide extraction techniques. The use of a larger sample (500g) ameliorates nugget-effect to a large degree. Cyanide dissolves very little of the surrounding matrix, and excellent detection limits can be obtained.
LabWest Code WCN-500: 500-4000g cyanide leach
Partial Leach Exploration
Partial Leach approaches are used where it is desired for metals to be extracted from surface coatings of soil grains, without dissolving the underlying host matrix. Metals adsorbed onto these outer layers or held in metallic oxide coatings on soil grains may have been mobilised through the soil profile, and can give good indications of orebodies deep under cover. Different leaches apply to different soil types, with some being more specific than others.
Please call Brad or Andrew to discuss the appropriate leach for your application and arrange an orientation study if required. Our partial leach extractions cover most requirements, from very benign (water leach), through broad-spectrum chelating (PL-01) to aggressive (aqua-regia).
Other leaches are available on request.
Partial Leach Scheme Codes
PL-01: Broad-spectrum, chelating cyanide-based leach.
PL-02: Water leach
PL-03: Sodium pyrophosphate leach (dissolves organic phase)
PL-04: Hydroxylamine-hydrochloride leach (weak or strong, dissolves manganese and iron oxide phases)
PL-05: Dilute aqua-regia leach
LabWest partial leach elements and detection limits: