Abstract: In this contribution, we review the occurrence state of gold in hydrothermal deposits and related analytical methods. The occurrence states of gold can be classified according to different criteria, but essentially they can be characterized as visible and invisible gold. The analytical methods include chemical phase analysis, physical identification, microbeam and spectroscopic analysis. At present, microbeam analysis techniques are widely used in SEM, EMPA, TEM, SIMS, SPM, LA-ICP-MS and so on, and these analytical methods can shed light on gold hydrothermal occurrence. Today we are still facing challenges in areas such as resolving the occurrence state of structural gold or valence state of Au in gold-bearing minerals, improving resolution and sensibility of microbeam analysis techniques, and overcoming obstacles in wave spectrum analysis. Improvements in microbeam analysis techniques and spectroscopic analysis will lead to more in-depth research on the occurrence state of gold.

Key words: gold, occurrence state, invisible gold, microbeam analysis techniques