Nanominerals, Mineral Nanoparticles, and Earth Systems

Hochella, Michael F.; Lower, Steven K.; Maurice, Patricia A.; Penn, R. Lee; Sahai, Nita; Sparks, Donald L.; Twining, Benjamin S.

doi:10.1126/science.1141134

Cited by 783 publications

(560 citation statements)

References 46 publications

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“…Anthropogenic nanoparticles are receiving increasing attention due to their unique role as agents of elemental transport and their increased reactivity in geologic systems (Chen et al, 2004;Hochella et al, 2008). The behaviour of mineral nanoparticles from pyrite ash in anthropogenic systems is still not well understood, due to a lack of experimental data on their physico-chemical properties.…”

Section: Implications For Human Healthmentioning

confidence: 99%

Chemical composition and minerals in pyrite ash of an abandoned sulphuric acid production plant

Oliveira

Ward

Izquierdo

et al. 2012

Science of The Total Environment

161

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The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich nanoparticles within the ash may contain high proportions of toxic elements such as As, 2 Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and nanominerals (e.g. oxides, sulphates, clays) in concentrations up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials.

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Section: Implications For Human Healthmentioning

confidence: 99%

Chemical composition and minerals in pyrite ash of an abandoned sulphuric acid production plant

Oliveira

Ward

Izquierdo

et al. 2012

Science of The Total Environment

161

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“…Thus, the estimated Hm/(Hm+Gt) does not stand for the bulk sample, rather for Hm/(Hm+Gt) in the clay fraction of the sample. Although Hm and Gt are often nanosize in natural systems [Hochella et al, 2008], Hm is more concentrated in the clay fraction than Gt because Gt has a greater tendency to form coatings on the sand and silt grains [Hao et al, 2009]. As a result, the Hm/(Hm+Gt) of the clay fraction should be higher than in the bulk samples.…”

Section: Quantification Of Coloring Iron Oxidesmentioning

confidence: 99%

“…[2] Iron oxides are widespread in earth systems and are highly concentrated near the surface as a result of aerobic weathering of Fe-bearing minerals [Hochella et al, 2008]. Iron oxides in soils and sediments can be divided into a magnetic group and a coloring group, distinct from each other according to their physical properties.…”

Section: Introductionmentioning

confidence: 99%

Rainfall-dependent transformations of iron oxides in a tropical saprolite transect of Hainan Island, South China: Spectral and magnetic measurements

Long

Balsam

2011

J. Geophys. Res.

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[1] The iron oxide content of soils and sediments controlled by weathering and pedogenesis is generally considered a reasonable indicator of climate. Previous studies in temperate zones have established a positive correlation in aerobic soils between ferrimagnets and low to moderate rainfall; the correlation seems to be reversed under extreme climates with high rainfall. Here we present a transect of saprolitic soils from Hainan Island, South China, with high rainfall (1440∼2020 mm/yr), little temperature variation (23∼24°C), and extreme weathering. Along this transect we observed that both hematite concentration and magnetic susceptibility decrease with increasing rainfall, whereas goethite concentration displays a large increase. However, there is no systematic trend in the total amount of iron oxides related to chemical weathering intensity along the transect. Goethite is the favored mineral phase of iron oxide with increasing rainfall and accumulates at the expense of hematite and maghemite through the dominance of rainfall-driven processes. These pedogenic processes coincide with the fundamentals of previous nonmonotonic models of hematite, magnetic susceptibility and rainfall control of an inflection point. This study also verifies a common genetic relationship between hematite and pedogenic ferrimagnets across a wide climate range. A conceptual model considering both rainfall and temperature is proposed to help interpret the mechanism of ferrimagnet formation and changes in the rainfall inflection point.

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“…Electrum nanoparticles are an example of "mineral nanoparticles" that can be present both as true nanoparticles, and also as larger minerals. Thus, they appear to occur as short-lived intermediaries between metal ions in true solution and minerals [32]. Metallic nanoparticles appear to form from supersaturated solutions and can form dendrites by the self-assembly and aggregation of the nanoparticles (Figure 1) [33].…”

Section: Introductionmentioning

confidence: 99%

Formation and Aggregation of Gold (Electrum) Nanoparticles in Epithermal Ores

Saunders

Burke

2017

Minerals

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Here, we review the concept that nanoparticles and colloids may have played a significant role in forming some types of hydrothermal ores deposits, particularly epithermal. This concept was first proposed almost a century ago but the development of new analytical technologies, lab experiments, and the discovery of new epithermal deposits where nanoparticles are evident have added credence to the "gold colloid theory". Nanoparticles are defined to have at least one dimension <10 −7 m, and may have different chemical and physical properties than the bulk solids. Colloids are typically <10 −6 m in diameter and have the added characteristic that they are dispersed in another medium. In epithermal ore-forming solutions, gold or electrum nanoparticles nucleate from supersaturated hydrothermal solutions, and thus this is a "far-from-equilibrium" process. In some cases, gold nanoparticles may simply play a transitory role of aggregating to form much coarser-grained crystals, where all of the evidence of nanoparticles precursor phases is not preserved. However, in some epithermal ores, silica nanoparticles also formed, and their co-deposition with gold (electrum) nanoparticles preserved the gold aggregation features as self-organized "fractal" dendrites. Here, we review existing the data on gold and electrum nanoparticles in epithermal ores, present images of electrum nanoparticles and their aggregates, and discuss the significance of gold nanoparticles formation and aggregation in helping to produce some of the highest-grade gold ores in the world.

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Nanominerals, Mineral Nanoparticles, and Earth Systems

Cited by 783 publications

References 46 publications

Chemical composition and minerals in pyrite ash of an abandoned sulphuric acid production plant

Chemical composition and minerals in pyrite ash of an abandoned sulphuric acid production plant

Rainfall-dependent transformations of iron oxides in a tropical saprolite transect of Hainan Island, South China: Spectral and magnetic measurements

Formation and Aggregation of Gold (Electrum) Nanoparticles in Epithermal Ores

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