Hydrothermal Deposits - Metals and Society: An Introduction to Economic Geology - page 87

Fig. 4.6 Photographs of (a) the open pit of the Chiquicamata porphyry copper deposit in northern
Chile, and (b) the open pit of the Exotica deposit near themain Chiquicamata deposit (PhotosN. Arndt)
The order in which the sulfides precipitate depends on solubility and tempera-
ture. Copper and Au react out at high temperature in the plumbing or stockwork
beneath the chimney and Fe precipitates as pyrite at the base of the pipe. The
chimney itself, as well as the 'smoke' from a black smoker, is composed of Zn and
Pb sulfides, as well as barite and anhydrite.
Analysis: VMS Deposits
Source of metals - volcanic and sedimentary rocks of the oceanic crust
Source of S - seawater sulfate
Source of fluid - seawater
Cause of fluid circulation - convection, commonly related to high-level
magma chambers
Precipitation process - cooling, change in redox state and dilution as
hydrothermal fluid reacts with seawater.