Reactions forming smythite, Fe9S11

This study evaluates the processes that form smythite, a mineral associated normally either with siderite in sedimentary iron formations and hydrothermal carbonate veins, or with pyrrhotite in nickel sulfide ore deposits. Smythite was found to form via either of two processes, the replacement of siderite in low temperature aqueous environments as proposed by Rickard (1968) or exsolution from high-temperature, S-rich pyrrhotite during cooling as proposed by Fleet (1982).