Precipitados de hierro en medios sulfato-ácidos que resultan de la alteración de anfibolitas ricas en sulfuros
ISSN: 0213-4497
Ano de publicación: 1989
Número: 14
Páxinas: 29-42
Tipo: Artigo
Outras publicacións en: Cadernos do Laboratorio Xeolóxico de Laxe: Revista de xeoloxía galega e do hercínico peninsular
Resumo
The basic iron sulfate jarosite is the main constituent of the precipitates formed from an acid mine drainage of pyrite rich amphibolite; complex sulfates, gypsum (in dry periods) and poorly crystallized iron oxides are also indentified. Oxidation and hydrolysis of Fe+2 released upon pyrite dissolution, together with hydrolysis of jarosite as pH raises, can originate the iron precipitates. Its evolution towards more crystalline forms may have been hindered by the high concentration of sulfate in water. On the contrary, goethite is very common in the oxidation zone of these amphibolites and its presence is justified by sulfate leaching simultaneous to a more gradual weathering.