“Invisible” Gold in Synthetic and Natural Arsenopyrite Crystals, Vorontsovka Deposit, Northern Urals

Noble Metal Speciations in Hydrothermal Sulphides

“…Conditions of analysis are provided in Appendix A Table A1. The AuMα line was chosen for Au analysis in arsenopyrite and pyrite (with 100-200 s counting time for PGE and Au) because it was established that the signal/background ratio of M series lines is better than that of L series lines [18]. These operating conditions and correctly selected background points made it possible to decrease the detection limit (3σ) down to 45 ppm for line AuMα.…”

“…One of the most relevant for the study of invisible gold is the Carlin deposit type [7,50,51,[95][96][97], where gold-bearing arsenopyrite is the predominant host mineral for gold in the ore (i.e., Au-concentrator, along with As-pyrite) with up to sub-wt% level of Au content. In this paper, we conducted a comparative study of the distribution of gold in 'Carlin' and 'pre-Carlin' arsenopyrites on the example of the Vorontsovka gold deposit in the Urals [18,63,80] (Figure 5). Studied arsenopyrite-bearing mineral assemblages were crystallised at the contrast TPX conditions (Table 3).…”

“…According to INAA data, pyrite from the sample Vr10-17 of the gold-skarn ore of the Vorontsovka deposit contains: As 4.3 wt%, Co 215 ppm, Sb 259 ppm, Ag 104 ppm and Au 2777 ppm. In this sample, a precision study of the relationship between the contents of Au and the main components of pyrite was performed by the EPMA method under conditions similar to those described in [18]. The correlation coefficient of As and Au in the pyrite crystal is 0.91 (N = 143).…”

“…2777 ppm. In this sample, a precision study of the relationship between the contents of Au and the main components of pyrite was performed by the EPMA method under conditions similar to those described in [18]. The correlation coefficient of As and Au in the pyrite crystal is 0.91 (N = 143).…”

“…The form in which gold occurs in sulphides of the Fe-As-S system, which are key minerals within the deposits of Au, Cu ± Au, Fe, Mo, U, Zn attracted enormous attention in the last quarter of the 20th century. From an experimental point of view, the limits of invisible gold in sulphides are defined over a wide temperature range [6,8,[12][13][14][15][16][17][18]. It is also determined experimentally that sulphide heating, as an analogue of metamorphic transformation, leads to release of chemically bound gold from the crystal lattice of host minerals (such as pyrite, arsenopyrite) and to the formation of elemental microparticles (for example, see the review of the problem in [15] and also the experimental data review in [19]).…”