Chemical and Physical Heterogeneity Within Native Gold: Implications for the Design of Gold Particle Studies
Chapman et al.
Mineralium Deposita, 2021
In gold exploration studies, single gold grains (or particles) from so-called “placer deposits” are often investigated to find the original mineralization source. In addition to the abundance of such gold grains, knowledge of their Au-alloy composition and mineral inclusions is important.
Robert Chapman and co-workers present a multi-method synopsis of a large set of gold grains from various locations. In addition to conventional methods such as electron probe microanalysis (EPMA), LA-ICP-TOFMS imaging was applied to a subset of grains– using the icpTOF R. The advantage of LA-ICP-TOFMS is that simultaneous measurement can accurately determine any co-variance of trace elements within gold grains, so that elements can be assigned to their mode of occurrence, i.e., as alloy components, mineral inclusions, or clusters.
In this study, Chapman et al. conclude that there is a high level of trace element heterogeneity, both within and between grains from the same locality, disproving the notion of a uniform distribution of trace elements within natural gold alloy. Therefore, the technique of high spatial resolution, multi-elemental imaging by LA-ICP-TOFMS holds great potential for future gold grain studies.