Gold analysis; fire assaying and alternative methods
Gold analysis; fire assaying and alternative methods (in Quality assurance, continuous quality improvement and standards in mineral resource estimation, Marcel A. Vallee (editor) and Alastair J. Sinclair (editor))
Exploration and Mining Geology (April 1998) 7 (1-2): 155-160
This paper describes fire assaying and 'high tech' alternatives for gold analysis, including the advantages and disadvantages of each method. These 'high tech' methods include instru neutron activation, aqua-regia digestion/atomic absorption, graphite furnace-atomic absorption or ICPMS and combinations of cyanidation with some of these methods. Fire assay remains the stalwart among analytical methods for gold but, even with its multiple ana finishes, is not fool-proof for 100% recovery of the gold present. Consumers of assays should not blindly trust the assay results without consideration of quality control data. Laboratories can and do make mistakes. Some of these can be easily discovered by due diligence. All these measures should ensure that gold analysis values from successive campaigns and from different laboratories meet acceptable levels of accuracy and precision, and can be correlated together, particularly when they occur in neighbouring holes. This is essential just as much for prospect evaluation as for project feasibility.