Schwertmannite,a new iron oxyhydroxysulfate mineral formed by bacterial oxidation of Fe(II) in SO42--rich acid mine waters, is of poorly crystallizable, special morphologic and highly reactive surface groups. In the light of these features, the authors hold that it may play an important role in translocation or attenuation of metals and metalloids. Formation, composition and structure of schwertmanite and its environmental behaviors with metals or metalloids are reviewed in this paper. Its potential application to the treatment of arsenic-bearing groundwater is also discussed in detail.