Sulfate oxy hydr oxides and related compounds

Jarosites are generally less soluble in acidic waters than under alkaline conditions. Although As(V) is known to partially substitute for sulfate in the mineral (Savage, Bird and Ashley, 2000), controversies exist over whether jarosites preferentially sorb more arsenic than their frequent decomposition product, goethite (Acero et al., 2006, 4137-4138). Examples of exceptionally arsenic-rich jarosites occur in mine tailings at Enguiales, Aveyron, France, where arsenic concentrations are approximately 5.7 wt% (Courtin-Nomade et al., 2003). 

In some circumstances, the oxidation of sulfide minerals to sulfate (oxy)(hydr)oxides involves one or more intermediate steps that are related to the properties of the field location. For example, realgar and orpiment in mining wastes at the Kusa mine in Sarawak, Malaysia, initially weather to arsenolite. The arsenolite readily dissolves in sulfate-rich waters in open pits. As the water evaporates, arsenic-rich jarosite precipitates (Williams, 2001, 274). 

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