1. 9 The nodule minerals consist of quartz, plagioclase, amphibole, K ? feldspar , goethite, lepidocrocite, δ MnO ? 2 , illite, and muscovite etc.

2. Some of the sorbed As(III) was released during lepidocrocite formation with a maximum in the presence of 1.0 mM Fe(II)aq (0.02 %, 21 μg L−1), presumably due to catalytic action of Fe(II)aq on schwertmannite dissolution, which likely re-precipitated as lepidocrocite with considerable surface-adsorbed SO42−.

3. Their mineral content is consisting of goethite, lepidocrocite, hematite, magnetite with some transformation to maghemite, siderite and the usual accompanying “gangue” minerals.