Skip to main content
U.S. flag

An official website of the United States government

Iron and aluminum hydroxysulfates from acid sulfate waters

January 1, 2000

Acid sulfate waters are produced mostly by the oxidation of common sulfide minerals such as pyrite, chalcopyrite, pyrrhotite, and marcasite in rocks, soils, sediments, and industrial wastes. This spontaneous process of mineral weathering plays a fundamental role in the supergene alteration of ore deposits, the formation of acid sulfate soils, and the mobilization and release of acidity and metals to surface and ground waters. The purely natural process of “acid rock drainage” is often intensified by human activities related to mining, mineral processing, construction, soil drainage, and dredging. Geochemical reaction rates are accelerated because physical disturbance gives greater exposure of mineral surfaces to air and water, and to microbes that catalyze the reaction process. Large quantities of reactive sulfides are also concentrated and exposed to air as a result of mining and mineral processing. Acid sulfate waters produce a number of fairly insoluble hydroxysulfate and oxyhydroxide minerals that precipitate during oxidation, hydrolysis, and neutralization. The objective of this chapter is to describe the formation, properties, fate, and environmental implications of the nano- to microphase hydroxy-sulfates of Fe and Al that are precipitated from acid sulfate waters. These minerals are commonly of poor crystallinity and difficult to characterize. Much remains to be learned about their occurrence, formation, and properties.

Publication Year 2000
Title Iron and aluminum hydroxysulfates from acid sulfate waters
DOI 10.2138/rmg.2000.40.7
Authors J.M. Bigham, D. Kirk Nordstrom
Publication Type Article
Publication Subtype Journal Article
Series Title Reviews in Mineralogy and Geochemistry
Index ID 70022459
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program