The zonal structure is remarkably conserved between the modern hydrothermal
vent systems and the ancient volcanogenic massive sulfide (VMS) deposits
of hydrothermal origin. VMS deposits can reach many kilometres in diameter,
and date back to the Archean period [185-187]. The ancient VMS deposits have
pyrite (FeS2) and chalcopyrite (CuFeS2) at their centres being encircled by consecutive
halos of, e.g., pyrite-chalcopyrite-sphalerite, sphalerite-galena-alabandite,
and, finally, chert [185,187]. ZnS crystals: Unique traits