Behaviour of mercury in the primary environment

As has been previously noted, the high volatility of Hg over a wide range of geological environments has led many authors to speculate on the possibility of broad primary dispersion halos surrounding sulphide deposits. Until about thirty years ago the only published case-history studies of the primary distribution of Hg around ore deposits were to be found in the Soviet literature. The most often-quoted example is that of Ozerova (1962, 1971), who studied the dispersion of Hg around Hg deposits as well as those containing Hg as a trace component. Of these the most pertinent to our considerations are the deposits of South Fergana, Uzbekistan. 

The deposits of South Fergana, described originally by Ozerova (1962), occur in Devonian to Permian carbonate and terrigenous sediments with minor intercalated volcanics. The Pb-Zn ores are described as being structurally controlled those deposits 

The Woodlawn volcanogenic Zn-Pb-Cu deposit is situated on the flank of a folded Middle to Upper Silurian volcaniclastic pile within the Lachlan Fold belt of eastern Australia (Malone et al., 1975). Primary ore comprises some 6 million tonnes of finely-banded complex massive sulphide ore (average grade 14% Zn, 5% Pb, 1.6% Cu and 88 g/t Ag). Ryall (1979b) compared the distribution of Hg with that of Cu, Pb, Zn, Ag, As and Sb in massive sulphide ore and wall rocks. The Hg content of massive sulphide ore ranges from 100-18,000 ppb and thermal release curves indicate Hg resides principally 

Sakrison (1971) briefly described a halo of anomalous Hg in drill core and surface rocks associated with a blind massive sulphide deposit near Noranda, Quebec. The halo 

Sharp (1976) analysed chert around the Hidden Creek massive sulphide deposit near Anyox, British Columbia. He showed that, although S dispersed more than 1 km beyond the recognised vent area, Ba, F and Hg show weak dispersion away from the sulphide occurrences. 

---