Stalactites containing 0.13–294 g kg⁻¹ As were collected from abandoned adits of the former Mikulov and Plavno mines (NW Czech Republic), and were then characterized by: X-ray diffraction, bulk chemical analysis, electron microprobe and Raman microspectrometry, chemical composition of the drip water, and analyses of the microbial communities. Several assemblages of mineral phases were identified: (i) straws of X-ray amorphous hydrous ferric arsenate (HFA) with younger kaňkite, (ii) pure HFA straws, (iii) straws composed of schwertmannite and HFA co-precipitates, and (iv) massive stalactites composed of X-ray amorphous hydrous ferric oxide (HFO) and HFA co-precipitates and minor hydrous manganese oxide (HMO). The chemistry of the drip water was closely linked to the solid phase composition of the stalactites. HFA- and schwertmannite-rich straws formed at pH < 4.4, while HFO-rich stalactites precipitated at a higher pH (>6.6). The concentrations of As and other trace elements (namely Pb and Zn) in the drip water is controlled by the solubility of HFA and/or sorption affinity of these elements to the schwertmannite, HFO, and HMO phases. Drying out of the HFA straws may lead to recrystallization and rearrangements of HFA, which result in formation of kaňkite and chemically anomalous HFA domains enriched in Ca, K, Mn, Pb, S, and Zn. Analyses of the stalactite's microbial communities revealed autotrophic oxidation of Fe, As, and S as the main factors driving formation of secondary minerals. Contrasting communities were found in similar mineral assemblages of stalactites, suggesting the high variability of microhabitats within each stalactite.

含0.13–294 g千克^-1的钟乳石从以前的Mikulov和Plavno矿山（捷克共和国西北部）的废弃矿山收集而来，其特征是：X射线衍射，本体化学分析，电子微探针和拉曼光谱，滴水的化学成分以及微生物群落。鉴定了几种矿物相组合：（i）X射线无定形含水砷酸铁（HFA）和较年轻的方解石风筝吸管；（ii）纯HFA吸管；（iii）schwertmannite和HFA共沉淀物组成的吸管；和（iv ）由X射线无定形含水三氧化二铁（HFO）和HFA共沉淀以及少量含水锰氧化盐（HMO）组成的块状钟乳石。滴水的化学性质与钟乳石的固相组成密切相关。pH <4.​​4时会形成富含HFA和schwertmannite的秸秆，而富含HFO的钟乳石在较高的pH值下（> 6.6）沉淀。滴水中As和其他微量元素（即Pb和Zn）的浓度由HFA的溶解度和/或这些元素对schwertmannite，HFO和HMO相的吸附亲和力控制。将HFA秸秆弄干可能会导致HFA重结晶和重排，从而导致形成钙矾石和富含Ca，K，Mn，Pb，S和Zn的化学异常HFA域。对钟乳石微生物群落的分析表明，Fe，As和S的自养氧化是驱动次生矿物质形成的主要因素。在类似的钟乳石矿物组合中发现了相反的群落，这表明每个钟乳石中微生境的高度变异性。滴水中As和其他微量元素（即Pb和Zn）的浓度由HFA的溶解度和/或这些元素对schwertmannite，HFO和HMO相的吸附亲和力控制。将HFA秸秆弄干可能会导致HFA重结晶和重排，从而导致形成钙矾石和富含Ca，K，Mn，Pb，S和Zn的化学异常HFA域。对钟乳石微生物群落的分析表明，Fe，As和S的自养氧化是驱动次生矿物质形成的主要因素。在类似的钟乳石矿物组合中发现了相反的群落，这表明每个钟乳石中微生境的高度变异性。滴水中As和其他微量元素（即Pb和Zn）的浓度由HFA的溶解度和/或这些元素对schwertmannite，HFO和HMO相的吸附亲和力控制。将HFA秸秆弄干可能会导致HFA重结晶和重排，从而导致形成钙矾石和富含Ca，K，Mn，Pb，S和Zn的化学异常HFA域。对钟乳石微生物群落的分析表明，Fe，As和S的自养氧化是驱动次生矿物质形成的主要因素。在类似的钟乳石矿物组合中发现了相反的群落，这表明每个钟乳石中微生境的高度变异性。