Application of PhotonAssay™ to Coarse-Gold Mineralisation – The Importance of Rig to Assay Optimisation

Simon C. Dominy, Janice C. Graham, Kim H. Esbensen and Saranchimeg Purevgerel

DOI: 10.62178/sst.001.002


Sample collection, preparation and assaying are a vital activity at all stages of a mining project. Field sample collection is followed by sample reduction in both mass and fragment size to provide a sub-sample for assay. This process can be particularly challenging in the precious metal environment and may require specifi cally designed protocols. One of the biggest challenges is ensuring that all sampling and subsampling errors are controlled across the entire rig to assay pathway. In most cases, the primary sampling error (the error at the rig and/or core shed) may swamp the entire process. Challenges also exist throughout all sampling stages when coarse gold is present. In particular, the pulp is likely to contain some liberated, poorly comminuted gold particles, requiring the pulp to be assayed in total to avoid unnecessary additional errors during splitting and handling. PhotonAssay™ is a non-destructive and rapid gold assay technique capable of analysing coarse crushed (<3 mm) 350-500 g samples at a rate of ~70 samples per hour. It displays fast assay turnaround-time, requires lower staffing levels to operate, and removes the need for chemicals such as lead or cyanide. These characteristics make it applicable to gold ores, particularly those bearing coarse gold, as only crushing is required (minimal liberated gold) and multiple lots can be assayed. However, this advantage will be reduced if any of the sampling stages are not optimised. The optimisation of a sampling protocol comes from understanding the mineralisation and desired programme outputs. It is not simply a mathematical, or a statistical process, but a complex process taking advantage of orebody knowledge (including gold deportment studies) and application of the Theory of Sampling.

Published in Issue 1 · January 2024

Citing this article

Dominy, S. C., Graham, J. C., Esbensen, K. H. & Purevgerel, S. (2024). Application of PhotonAssay™ to Coarse-Gold Mineralisation – The Importance of Rig to Assay Optimisation. Sampling Science & Technology, January 2024(1), 2-30.


Craig Hamlyn (Ore Research & Exploration Pty Ltd) is thanked for pointing out ambiguous statements regarding, and constructive discussions of, the reasons behind recertification of OREAS CRMs, which led to the release of a revised version of the paper. SST regrets the inconveniences caused by this.


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