23 24 Large rounded pyrite grains (>1 mm), commonly referred to as ‘buckshot’ pyrites, are a characteristic feature of 25 the auriferous conglomerates (reefs) in the Witwatersrand and Ventersdorp supergroups. Detailed petrographic 26 analyses of the reefs indicated that the vast majority of the buckshot pyrites are of reworked sedimentary origin, 27 i.e., that the pyrite originally formed in th...

Cellular exposure to particulate matter with concomitant formation of reactive oxygen species (ROS) and oxidization of biomolecules may lead to negative health outcomes. Evaluating the particle-induced formation of ROS and the oxidation products from reaction of ROS with biomolecules is useful for gaining a mechanistic understanding of particle-induced oxidative stress. Aqueous suspensions of p...

This study investigated the impact of mechanically modified pyrite on dearsenification arsenopyrite through bacterial oxidation. Pyrite was using a planetary high-energy ball mill, and resulting changes in crystal structure were characterized particle size analysis, specific surface area measurements, scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD). Pearson corre...

A new method is described for determining in shales the amount of sulphides that dissolve in dilute hydrochloric acid. 1he samples are treated with hydrochloric acid under vacuum, and the hydrogen sulphide evolved is absorbed in potassium hydroxide and titrated with potassium _~'~ermanganate. The analytical results are expressed as FeS. INTRODUCTION During a study of the distribution of the sul...

The formation of pyrite (FeS2) from iron monosulfide precursors in anoxic sediments has been suggested to proceed via mackinawite (FeS) and greigite (Fe3S4). Despite decades of research, the mechanisms of pyrite formation are not sufficiently understood because solid and dissolved intermediates are oxygen-sensitive and poorly crystalline and therefore notoriously difficult to characterize and q...

Pyrite (FeS2) is a major iron- and sulfur-containing mineral phase in the environment. Oxidation of pyrite by aerobic micro-organisms has been well investigated. However, the reactivity of pyrite under anoxic conditions is still an open question. In the present paper, we summarize field and laboratory data on this chemolithotrophic respiration process with nitrate as terminal electron acceptor....

Despite its exceptional optical absorptivity, suitable band gap, and earth abundance, the low open-circuit voltage of pyrite FeS2 has remained the biggest challenge preventing its use in photovoltaic devices. Two widely-accepted causes are: (i) Fermi level pinning caused by intrinsic surface states that appear as gap states; (ii) presence of the polymorph marcasite. Based on density-functional ...