Schwertmannite is an iron hydroxo sulfate secondary mineral (Fe₈O₈(OH)_8-2x(SO₄)_x•nH₂O; 1 ≤ x ≤ 1.75) that commonly precipitates in sulfate-rich acid and metalliferous drainage as Fe(II) oxidises to Fe(III). It displays a high capacity to incorporate a range of elements through substitution of metal cations for Fe and anionic species for inner-sphere and outer-sphere sulfate groups, and surface adsorption. Precipitates from the base to top of sediment profiles immediately downstream from the historic Sunny Corner sulfide deposit are dominated by schwertmannite, indicating the stability of this mineral over decadal time frames in the low pH and high sulfate conditions. Various mineral characterisation methods, coupled with hydroxylamine hydrochloride based sequential selective extractions, reveal two forms of schwertmannite co-existing and in similar proportions throughout the profiles. The first form of schwertmannite has a high S/Fe ratio and the pattern of release of Cu, Pb, Zn and As relative to Fe indicates such trace elements are mostly adsorbed to outer-sphere sites. By contrast, the second and more crystalline schwertmannite has lower S/Fe ratios and requires higher concentrations of hydroxylamine hydrochloride to dissolve. The second schwertmannite displays substantial substitution of arsenate for sulfate, with As/(As + S) molar ratios ranging from 0.1 to 0.6, and substantially higher concentrations of trace elements. Sequential precipitation of the two schwertmannites from the AMD appears more likely than transformation of one form to the other. At sites such as Sunny Corner, pH neutralisation or removal of sulfate from the AMD stream may result in destabilisation of the schwertmannite and release of associated trace metals.

Schwertmannite 是一种羟基硫酸铁次生矿物(Fe ₈ O ₈ (OH) _{8-2 x} (SO ₄ ) _x •nH ₂ O；  1≤x ≤ 1.75)，通常在富含硫酸盐的酸和含金属废水中沉淀，因为 Fe(II) 氧化成 Fe(III)。通过用金属阳离子代替 Fe 和阴离子物质代替内球和外球硫酸盐基团，以及表面吸附，它显示出结合一系列元素的高能力。从位于历史悠久的 Sunny Corner 硫化物矿床下游的沉积物剖面底部到顶部的沉淀物以施韦特曼石为主，表明这种矿物在低 pH 值和高硫酸盐条件下的十年时间框架内的稳定性。各种矿物表征方法，加上基于盐酸羟胺的连续选择性萃取，揭示了两种形式的施韦特曼石共存且在整个剖面中以相似的比例存在。第一种形式的施韦特曼石具有较高的 S/Fe 比，并且相对于 Fe 的 Cu、Pb、Zn 和 As 的释放模式表明这些微量元素主要吸附到外球位。相比之下，第二种和更多结晶的施韦特曼石具有较低的 S/Fe 比，并且需要较高浓度的盐酸羟胺来溶解。第二种施韦特曼石显示出大量砷酸盐替代硫酸盐，As/(As + S) 摩尔比在 0.1 到 0.6 之间，微量元素的浓度明显更高。两种施韦特曼石从 AMD 连续沉淀似乎比从一种形式转变为另一种形式更有可能。在 Sunny Corner 等网站，