Jarosite dissolution rates and nanoscale mineralogy

The labyrinthine world of arsenic minerals has piqued the curiosity of many researchers in mineralogy, geochemistry, chemistry, and environmental sciences. Arsenic was known to the ancient civilizations; there are written Greek, Roman, and Chinese reports about minerals and substances of this element (Emsley 2001). The discovery of elemental arsenic is attributed to Albertus Magnus (1193–1280) who prepared it by reduction of As2O3. The common public association of arsenic and poison is the heritage of a long history of eliminating unwanted and unloved ones with compounds of this element. Mary Ann Cotton (1832–1873) was charged with murder of her mother, three husbands, a lover, eight of her own children, and seven stepchildren, all of them with an arsenic-based de-worming compound (Emsley 2005). Kořinek (1675) gave a vivid and frightening account on how a natural ferric sulfo-arsenate (bukovskýite) was used to poison the German armies of Albrecht Habsburg who invaded Bohemia in 1304. An arsenic derivative called lewisite (2-chlorovinyl-dichloroarsine) was used in the World War I (Emsley 2001). On the other hand, brightly-colored arsenic compounds were used in all imaginable products well into the 20th century. Arsenic whetted the appetite of many children as green arsenical chemicals were used as cake decorations and coatings of sugar sweets (Emsley 2005). The death of Napoleon Bonaparte has been regarded for a long time as a consequence of ingested or inhaled arsenical compouds (e.g., Aldersey-Williams 2011), however there are alternative interpretations (Lugli et al. 2011). Accidental mass arsenic poisoning occurred in Manchester in 1900 when many men drank beer contaminated with arsenic. The arsenic was tracked back to pyrite which was used to produce sulfuric acid which was employed in the manufacture of glucose for this batch of beer (Emsley 2005). Despite its toxicity, arsenic finds a few uses in …

Parageneses and Crystal Chemistry of Arsenic Minerals

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1193&context=usdoepub

Mineralogical transformations controlling acid mine drainage chemistry

https://repository.arizona.edu/bitstream/10150/633297/1/Surficial_weathering_of_iron_sulfide_mine_tailings_Hayes_15_pub_access.pdf

Surficial weathering of iron sulfide mine tailings under semi-arid climate.

As antibiotic-resistant bacterial strains emerge and pose increased global health risks, new antibacterial agents are needed as alternatives to conventional antimicrobials. Naturally occurring antibacterial clays have been identified which are effective in killing antibiotic-resistant bacteria. This study examines a hydrothermally formed antibacterial clay deposit near Crater Lake, OR (USA). Our hypothesis is that antibacterial clays buffer pH and Eh conditions to dissolve unstable mineral phases containing transition metals (primarily Fe2+), while smectite interlayers serve as reservoirs for time release of bactericidal components. Model pathogens (Escherichia coli ATCC 25922 and Staphylococcus epidermidis ATCC 14990) were incubated with clays from different alteration zones of the hydrothermal deposit. In vitro antibacterial susceptibility testing showed that reduced mineral zones were bactericidal, while more oxidized zones had variable antibacterial effect. TEM images showed no indication of cell lysis. Cytoplasmic condensation and cell wall accumulations of 630 mV and contain elevated level (mM) of soluble Fe (Fe2+ and Fe3+) and Al3+. Our interpretation is that rapid uptake of Fe2+ impairs bacterial metabolism by flooding the cell with excess Fe2+ and overwhelming iron storage proteins. As the intracellular Fe2+ oxidizes, it produces reactive oxygen species that damage biomolecules and precipitates Fe-oxides. The ability of antibacterial clays to buffer pH and Eh in chronic non-healing wounds to conditions of healthy skin appears key to their healing potential and viability as an alternative to conventional antibiotics.

Mineralogical variables that control the antibacterial effectiveness of a natural clay deposit

Mine-drainage waters and associated precipitates from several active and abandoned lignite mines and mine dumps in the Sokolov Basin, northwestern Czech Republic, were sampled and analysed. The data showed considerable variations of effluent composition and pH that can generally be related to differences in the local microenvironments. Temporal changes such as seasonal fluctuations of precipitation, leading to variations of water infiltration through and runoff over mines and mine dumps, were also observed to noticeably affect effluent composition. These variations have led to a wide range of precipitates, the principal constituents of which are generally one or several of the ferric minerals jarosite, schwertmannite, goethite, ferrihydrite and lepidocrocite.

The present paper consists of two parts: a short review of the genesis and properties of the named minerals, and a study of mine-drainage precipitates formed under different local conditions in various lignite mines and mine dumps of the Sokolov mining district. We show that variations in mine-drainage precipitate mineralogy, such as the presence or absence of specific ‘key’ minerals, can serve as indicators for factors such as the pH and sulphate concentration, and thus – with certain limitations – for the genetic environment during precipitate formation. Such variations in composition are reflected, among other properties, in the precipitate colour, which can therefore be used for a rapid identification and classification – both in the field and by remote sensing – of regions that are potentially prone to acid mine drainage.

Iron mineralogy of mine-drainage precipitates as environmental indicators: review of current concepts and a case study from the Sokolov Basin, Czech Republic

P. Rojík

Papers

Iron mineralogy of mine-drainage precipitates as environmental indicators: review of current concepts and a case study from the Sokolov Basin, Czech Republic