Trace metal substitution in and release from jarosite

Historical mines were often unregulated and may release acidic, metal-rich water known as acid mine drainage (AMD) that results from the dissolution of metal sulfides. A common AMD remediation method is neutralization of pH. This causes precipitation of secondary iron hydroxide minerals and dissolved metals from solution. The stability of trace metal substituted (TMS) iron hydroxides is not well understood. This study investigates the mobility of trace metal ions, specifically cobalt, as it is substituted into the mineral structure of jarosite [KFe₃(OH)₆(SO₄)₂]. Leach experiments were conducted with synthesized pure and cobalt substituted jarosite. In addition, the character of water and precipitate samples from Blackbird Creek, a mining-affected, remediated stream in the Idaho Cobalt Belt are described. The goal of this work is to understand how cobalt substitution affects the stability of jarosite and to compare synthetic jarosite to that in sediments found at Blackbird Creek.