Coatings result from the wide variety of reactions and/or processes that occur at the interface between the lithosphere and the biosphere, hydrosphere, and atmosphere. Such coatings are biochemically, mineralogically, and isotopically complex and have the potential to record changes in their immediate environment. The transition between a coating and its underlying host is abrupt and defined by a sharp interface at the nanoscale. Articles in this issue highlight new and exciting research in the field of coatings, focusing on coatings formed in deserts, soils, sediments, oceans, and on rocks from Mars.
Despite the bulk silicate Earth only containing 250 parts per million of sulfur, sulfide minerals and liquids have a powerful impact on the behavior and fractionation of a wide range of elements in the Earth’s crust and underlying mantle. This issue focuses on the broad topics of magmatic and volcanogenic sulfide deposits, the behavior of sulfides during mantle melting and volcanism, and the mineralogy of sulfides and sedimentary sulfides and their role in the early development of the biosphere.
Volcanoes are the powerhouses of nature that can, within minutes, transform a beautiful mountainscape into a desolate landscape devoid of life. Whether eruptions are mild or catastrophic, volcanoes fascinate and captivate us. But what controls whether a given magma will erupt or stall, and how do processes in one part of the system affect others? Volcano science is advancing rapidly, and improvements in monitoring tools, petrologic tools, and modeling of volcanic processes have greatly improved our understanding of volcanic behavior. This issue brings together contributions exploring volcanic behavior throughout the crustal system.
December 2016 - Origins of Life: Transition from Geochemistry to Biogeochemistry
How did life arise from inorganic molecules? Did it develop in an early Earth primordial soup or was there an extraterrestrial source? The answers to these questions require chemical, biological, and geological considerations. Although the scientific answer to the origin of sentient life has yet to be discovered, the origins of the genetic blueprints for life (e.g. RNA), the workhorses of life (e.g. proteins), and the protective membranes for life (e.g. lipids) are rapidly being uncovered. But, making the basic building blocks is only the first step. The next steps involve converting those molecules into viable cells that can metabolize and reproduce under relevant geochemical environmental conditions. The articles in this issue will introduce you to this exciting interdisciplinary field of research.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a mature, but still developing, micro-analytical technique that has allowed significant research advances in many areas of the Earth sciences. The method produces quantitative elemental and isotopic analyses on the micrometer scale of most solid, and some liquid, materials across most of the periodic table. A key strength of the method is that it can detect changing conditions or processes over time by analysis of growth zones or domains in minerals and other objects. Because both inorganic and organic materials can be analyzed, abiotic and biotic processes, and their interactions, can be studied. This issue of Elements highlights applications of LA-ICP-MS across the broad range of disciplines of interest to the Earth, environmental, and biological sciences that now rely on the technique and their interdisciplinary nature.
August 2016 - Deep-Mined Geological Disposal of Radioactive Waste
The construction of geological disposal facilities for radioactive waste will become a major focus of geological, mineralogical, and geochemical effort in coming years. Geological disposal raises complex technical issues, but it is also at the center of social and political controversy. Different countries have very different waste inventories and quantities of waste; they may also have different geological settings available to host a repository. The issue presents five case studies for the concepts for repositories hosted in clay, granite/gneiss, salt, and tuff. The varied approaches to selecting a site that is acceptable to local communities will be reviewed.
Cosmic dust is submillimeter debris shed by comets, asteroids, moons, and planets. These small particles are the largest source of extraterrestrial material accreting on the present-day Earth. Although atmospheric entry heating and terrestrial weathering modify many particles, some are pristine primitive extraterrestrial materials that contain high abundances of isotopically anomalous presolar grains and primitive carbon compounds that have not been altered since their formation. Analysis of cosmic dust provides invaluable information on initial planetary building materials and formation of our Solar System.
April 2016 - Enigmatic Relationship Between Silicic Volcanic and Plutonic Rocks
The relationship between silicic volcanic and plutonic rocks has long puzzled geologists. Do granites and rhyolites share a common origin or are they derived from completely different processes? This issue explores the rich set of observations from petrology, geochronology, thermal modeling, geophysical techniques, and geochemistry used to study the silicic volcanic-plutonic relationship. Finding a consistent explanation for the silicic volcanic–plutonic relationship bears on important Earth science questions, including, “How is silicic continental crust formed?” and, “Can we predict supereruptions?”
February 2016 - Earth Sciences for Cultural Heritage
This issue of Elements celebrates the diverse contributions that the Earth sciences have made to characterizing, interpreting, conserving, and valorizing cultural heritage. As demonstrated in these articles, Earth scientists possess a profound perception of the complexity of natural materials, they have the necessary knowledge of the ancient and recent geological and physicochemical processes acting on natural materials and on the artifacts produced by human activities, and they employ techniques essential for the investigation of our common heritage. Earth scientists greatly contribute towards a better understanding and preservation of our past. [Artioli and Quartieri (2016) Elements 12:13-18]
December 2015 - Geomicrobiology and Microbial Geochemistry
Microbes exert significant geochemical and mineralogical control on local environments through their metabolic and growth needs. In turn, local geochemical conditions dictate what metabolic processes are possible. This thematic issue is focused on the interface between the Earth, environmental systems, and microbial life. The latest discoveries, theories, “omic” methods, and emerging frontiers in the area of geomicrobiology and microbial geochemistry are discussed.
Supergene metal deposits form when deeply buried ore bodies are exposed at the Earth's surface and undergo oxidation, dissolution, and significant reconcentration of metals. This issue highlights some of the most recent advances in the field, including cutting-edge research in economic geology, paleoclimate and geoarcheology studies, environmental geochemistry, geobiology, and corrosion science.
August 2015 - Societal and Economic Impacts of Geochemistry
Geochemistry can be applied to a variety of societally and economically important areas, including: mineral exploration; environmental mineralogy; environmental problems in cities, using London (England) as a case study; food industry authenticity; law enforcement; and medical advancements. A significant driver for the research described in all of these articles is analytical achievement and translating this to a societal application.
Apatite, number 5 on the Mohs scale of hardness, is one of the first minerals that students of geology learn. Because it was commonly confused with other minerals, apatite was not recognized as a distinct mineral species until the late 18th century. The name apatite is derived from the Greek wordά which means "to deceive." Despite what early mineralogists may have thought of its "deceptive" nature, over the next two centuries apatite was gradually recognized to be the most common phosphate mineral in the Earth’s crust and lithospheric mantle where it subsequently acts as a major reservoir for P, F, Cl, OH, CO2, and many trace elements including the rare earths. This issue introduces apatite as a ubiquitous accessory mineral, which is also related to a supergroup family of over 40 other minerals, and then explores its multi-varied roles as a recorder of both terrestrial and extraterrestrial metasomatic and igneous processes, as a thermochronometer over a wide pressure-temperature range, and as a mineral with numerous technological and biological applications.
The differentiation of our planet and formation of the continental crust, and its underlying mantle lithosphere, are in large part the result of magmatic processes at convergent margins. These magmatic processes are important to issues of societal interest such as the evolution of life, mineral and energy deposits, volcanic and fault hazards, and long-term climate change. Magmatism in oceanic and continental convergent arcs is not temporally or spatially steady-state, rather it occurs in pulses and lulls. The articles in this issue explore the tempo of magmatism as recorded in the rock record, investigate the causes of high-volume events in subduction-related magmas, and provide an overview of recently developed models to explain episodic behavior in subduction magmatism.
The Mars Science Laboratory (MSL) rover Curiosity was designed and built to explore the surface of Mars and characterize its modern environment. Its primary objective was to search for ancient habitable environments. During its nominal one-Mars-year mission (23 Earth months), Curiosity drilled and scooped samples, made mineralogical, isotopic, and compositional measurements, took hundreds of thousands of images that provided geologic context for samples, and acquired millions of observations of the modern environment.Curiosity is the most advanced mobile geochemistry laboratory to have ever roved another planet, and it has been very productive. Within 8 months of landing, scientists were able to confirm mission success with evidence of an ancient habitable environment on Mars. This issue presents the range of discoveries related to the investigations of the solid materials at Gale Crater and elsewhere on Mars. [Grotzinger et al. (2015) Elements 11:19-26]
Graphitic carbon, with its diverse structures and unique properties, is everywhere at the Earth’s surface. Strategically located at the interface between the lithosphere, biosphere, hydrosphere, and atmosphere, graphitic carbon constitutes a major terrestrial carbon reservoir. Natural and synthetic graphitic carbon is also used in a broad range of applications. Graphitic carbon has played an important role in human history (for example, coal mining) and is now a building block of nanotechnology, but this remarkable material is also an active player in geological processes. From Beyssac and Rumble, Elements 10: 415-420.
Cosmogenic nuclides illustrate a frontier area that is fast moving thanks to improvements in analytical instrumentation. It is interesting to see that theoretical developments in particle physics have found applications in our effort to understand today’s landscapes. Guest editors Friedhelm von Blanckenburg and Jane Willenbring, together with the cast of authors they assembled, chose to illustrate how cosmogenic nuclides can help us understand Earth-surface processes. And the Toolkit article shows off the technological prowess needed to measure these rare nuclides—one atom in a million billion.
Unconventional hydrocarbons, such as gas and oil shale, oil sands, and heavy oil, can now be exploited more effectively and economically. This has stimulated exploration and exploitation on a global scale and has led to a new economic and environmental landscape in energy matters. Exploiting unconventional hydrocarbons requires additional technology, energy, and capital compared to the industry standard. In this thematic issue, Guest editors David Cole and Michael Arthur address the geologic and geochemical nature of these resources and their impact on global socioeconomics and the environment.
The issue on kaolin illustrates admirably how materials known and used since the dawn of humanity may still have many surprises in store for us in terms of new uses and applications. Guest Editors Paul Schroeder and David Bish chose to present the whole spectrum of uses of kaolin, from ancient porcelains to nanocomposites. Kaolin-group minerals are among the most important industrial clay minerals, with a worldwide consumption in the millions of tons per year and applications in a wide range of industrial areas. Traditionally, their most important use has been in the paper and ceramic industries. New, innovative techniques have now allowed the synthesis of kaolinite–polymer nanocomposites, including bionanocomposites.
"Ophiolites... How do these rocks form and where do we find them? What tectonic secrets do they reveal? Much has been learned since the first Penrose definition of an ophiolite. Multiple tectonic settings are now recognized and are summarized in this issue, and a geochemical basis is presented for their identification. The classic localities of Oman and the Izu-Bonin-Mariana arc are described in detail. This issue also reports on the discovery of diamonds and an amazing array of reduced and exotic minerals in chromitites from several ophiolites. The alteration of basaltic glass in ophiolites may even lead to the recognition of primitive life-forms on the seafloor of the early Earth. The study of ophiolites and their mineralogy, petrology, and geochemistry, has never been more fascinating or relevant to mankind.” Excerpt from John Valley’s editorial Playthings versus the Killer Rock?
February 2014 - Asteroids: Linking Meteorites and Planets
At present, we know of ~600,000 asteroids in the asteroid belt, and there are very likely millions more. Orbiting the Sun between Mars and Jupiter, they are thought to be the shattered remnants of small bodies formed within the young Sun's solar nebula that never accreted enough material to become planets. These “minor bodies” are therefore keys to understanding how the Solar System formed and evolved. As leftover planetary building blocks, they are of great importance in understanding planetary compositions. They may also provide clues to the origin of life, as similar bodies may have delivered organics and water to the early Earth. For these reasons, several international space agencies have funded sample- return missions to asteroids.
December 2013 - Garnet: Common Mineral, Uncommonly Useful
Garnet is among the most studied—and most beloved—minerals, owing to its commonality in diverse geologic contexts, its often large euhedral crystals, its sometimes dazzling colors, and its propensity for preserving information about its growth history. Chemically zoned garnet represents a remarkable tool for deciphering metamorphic conditions and the evolving tectonic processes that drive garnet growth over many millions of years. In the deep Earth, garnet is a key rock-forming mineral, influencing the physical properties of the mantle and the composition of mantle-derived magmas. Garnet has been sought for ages as a semiprecious gemstone (the birthstone of January) and has been mined or synthesized (including nonsilicate garnet) for industrial purposes, including laser, magnetic, and ion-conductor technology. This issue of Elements will emphasize the most recent innovations in thermodynamic, geochemical, geochronologic, and industrial applications of garnet, while providing perspective on decades of garnet-related research.
December 2013 – Volume 9 Number 6 Garnet: Common Mineral, Uncommonly Useful
Ethan F. Baxter, Mark J. Caddick, and Jay J. Ague
October 2013 - Nitrogen and Its (Biogeoscosmo) Chemcial Cycling
Nitrogen is the most abundant element in Earth’s atmosphere and a key component of the biosphere. It is also a critical part of the surface/near-surface cycling of nutrients, thus directly impacting our lives. Changes in the biogeochemical cycling of nitrogen through Earth’s history could reflect fundamental changes in its pathways from inorganic to biological reservoirs in response to change in the environment (e.g. oxygen fugacity in the atmosphere and oceans). Recognition of the importance of nitrogen to life on Earth, and likely elsewhere in the Solar System, has led to the mantra “Follow the Nitrogen” as one vehicle for focusing efforts in the search for extraterrestrial life. Nitrogen serves as a useful tracer of the transfer of “organic” signatures into the deep Earth (in records preserved in metamorphic and igneous rocks and in volcanic gases and rocks). It has been speculated that biological fixation of nitrogen and storage in rapidly forming continental crust has led to drawdown of nitrogen from the early-Earth atmosphere, strongly influencing the chemical evolution of the atmosphere and related surface conditions.
October 2013 – Volume 9 Number 5 Nitrogen and Its (Biogeocosmo) Chemical Cycling
Gray E. Bebout, Marilyn L. Fogel, and Pierre Cartigny
The discovery of diamond and coesite in crustal rocks is compelling evidence that continental material has experienced pressures that can be achieved only at mantle depths. The classical idea that continents are too buoyant to subduct has given way to the notion of density changes driving deep subduction during the collision process, thus enabling some crust to be exhumed to the surface and the rest to sink into the mantle. Over twenty localities of unequivocal continental crust containing diamond or coesite are now recognized around the globe, and their study constitutes a new field in petrology, dubbed ultrahigh-pressure metamorphism. Using microscopic observations, phase equilibrium modeling, geochronology, and geodynamic modeling, we track the journey of ultrahigh-pressure rocks to the mantle and back. Continental ultrahigh-pressure terranes impact our understanding of plate tectonics through time, crustal recycling and mantle geochemistry, melting in subduction zones, and collisional processes in general.
August 2013 – Volume 9 Number 4 Continental Crust at Mantle Depths
Reactions occurring at mineral–water interfaces are central to geochemical processes. They affect a wide range of important environmental issues, such as the composition of natural waters, weathering and soil formation, element cycling, biomineralization (including minor-element incorporation), acid mine drainage, and nuclear waste disposal. Recent studies using state-of-the-art spectroscopic and microscopic techniques have characterized the molecular structure of mineral surfaces, the distribution of fluids near surfaces, and dynamic processes such as dissolution, growth, and mineral replacement. These studies provide insights into the kinetics and mechanisms of reactions occurring at mineral surfaces, and they test the validity of predictions based on theory. These recent advances constitute the central theme of this issue of Elements. Modeling approaches used in mechanistic studies are also introduced. Such approaches complement direct, in situ, molecular-scale observations of processes occurring at mineral–water interfaces.
June 2013 – Volume 9 Number 3 The Mineral-Water Interface
Christine V. Putnis and Encarnación Ruiz-Agudo
Serpentinites, primarily composed of serpentine minerals and formed by hydration of peridotites, increasingly attract the attention of a wide range of scientists, including geophysicists, structural geologists, engineers, and astrobiologists. As serpentinites have wide stability fields, they form in a variety of environments, from the Earth’s surface to the interior of the mantle. They are important as reservoirs of water in the deep mantle and in the recycling of elements in subduction zones. Because of their physical properties, serpentinites play important roles in seismic activity and geodynamics, including earthquakes in subduction zones, rifting, oceanic spreading, strike-slip faulting, and the exhumation of deeply subducted rocks. Serpentinites are also economically important because obducted serpentinites contain more than half the world’s reserves of nickel. The formation of serpentinites is accompanied by the production of hydrogen and methane, producing unique ecosystems on the ocean floor. The generation of hydrocarbons during serpentinization is the essential first step in the origin of life on Earth and possibly other planets.
February 2013 - One Hundred Years of Isotope Geochemistry
In 1913, Frederick Soddy’s research on the fundamentals of radioactivity led to the discovery of “isotopes.” That same year, Arthur Holmes published his now famous booklet The Age of the Earth. Combined, these two landmark events established the field of science we know as “isotope geochronology.” Today, isotope geochronology underpins much of our knowledge of the absolute age of minerals and rocks, and the records they contain. This field is constantly evolving, reflecting and responding to scientific drivers that require more highly resolved timescales, the microscopic analysis of smaller zoned minerals, or the generation of robust data sets in novel materials. This series of articles provides perspectives on the state of the art in the field of radioisotope dating—from the challenges of dating the Solar System’s oldest materials to resolving the record of Quaternary climate change, and the four and a half billion years in between.
February 2013 – Volume 9 Number 1 One Hundred Years of Geochronology
Daniel J. Condon and Mark D. Schmitz
By 2030, about 60% of the human population will live in cities. Clearly, anthropogenic activities in urban environments affect geochemical cycles, water resources, and the health of ecosystems and humans globally. Past practices are still having biogeochemical impacts today, and in many cases remediation is needed. Both natural and man-made disasters greatly change the geochemistry of urban areas. Understanding past impacts can aid in future disaster planning. An increased awareness of the geochemical and mineralogical effects of urbanization on geochemical cycling will aid urban planners in the effort to make urban development sustainable.
December 2012 – Volume 8 Number 6 Urban Geochemistry
W. Berry Lyons and Russell S. Harmon
Rare earth–based materials have practical applications in transportation, renewable energy, medicine, household items, visual arts, forensic science, and defense, and thus are essential to the progress of humankind. The rapid development and implementation of innovative and green technologies in the past decade have resulted in greatly increased demand for rare earth elements (REE). This demand has been amplified by the current situation in the supply market and by growing public concern about unlawful or unethical extraction of certain rare-metal resources. The renewed interest in rare earth resources in the exploration and public sectors requires a much better understanding of these resources and their host rocks than currently available. This thematic issue will present a comprehensive overview of the key geological, geochemical, and mineralogical aspects of REE distribution in the crust and principal deposit types. It will also discuss economic, political, and environmental issues related to REE mining.
October 2012 – Volume 8 Number 5 Rare Earth Elements
Anton R. Chakhmouradian and Frances Wall
Nothing that geoscientists learn as students prepares them for interpreting rock textures as complex as those found in pegmatites. Understanding the textures and mineral zonation of granitic pegmatites is tantamount to understanding the fundamental process of crystallization. It is a challenge to our ability to discern, beyond reasonable doubt, what is igneous and what is hydrothermal. This is the context that has drawn many professional geoscientists to the study of pegmatites for all or part of their careers. In addition, granitic pegmatites are important to our society as sources of raw materials for glasses and ceramics, silicon for microprocessors, and specialty metals including Li, Cs, Be, Nb, Ta, Sn, REE, and U. A very few pegmatites provide some of the most highly prized mineral specimens and colored gems found in national museums and personal collections around the world. No other rock type presents such a diversity of economic commodities in such concentrated fashion.
August 2012 – Volume 8 Number 4 Granitic Pegmatites
On March 11, 2011, an earthquake and tsunami hit Japan, killing more than 20,000 persons, displacing tens of thousands, and causing havoc in the infrastructure and economy of the country. In the aftermath of this tragedy, the cooling systems of three of the operating reactors at the Fukushima Dai-ichi nuclear power station failed and meltdown of the reactor cores occurred. Over the following days, a series of hydrogen gas explosions took place. Radionuclides (mainly 131I and 137Cs) were released to the atmosphere and transported over many tens of kilometers from the site, contaminating soil and water. Seawater was used to cool the damaged reactor cores, and water contaminated with radioactivity was released to the ocean. Considerable amounts of used fuel were stored in nearby pools, and with the loss of water, the pools contributed to the release of radioactivity. One year after the tragedy at Fukushima, this issue of Elements provides a summary of what is known about the environmental impact of this nuclear accident.
June 2012 – Volume 8 Number 3 Fukushima Daiichi
Takashi Murakami and Rodney C. Ewing
Studies of mineral–microbe interactions lie at the heart of the emerging field of geomicrobiology, because minerals are the fundamental Earth materials with which microbes interact. Microbes are found in a number of the Earth’s extreme environments and also in extraterrestrial materials. In spite of the diverse geological environments in which microbes are found and the various approaches taken to study them, a common thread—mineral–microbe interactions—connects all these environments and experimental approaches and places them under the same umbrella: geomicrobiology. Minerals provide microbes with energy and living habitats, and microbes impact mineral weathering and diagenesis. The recognition of mineral–microbe interactions has revived the classical discipline of mineralogy, and microbes discovered in various habitats have provided microbiologists with unique opportunities for study. This issue considers microbially mediated mineral dissolution, precipitation, and transformation, and the synergistic relation between minerals and microbes for energy acquisition. These interactions have important implications for contaminant remediation.
April 2012 – Volume 8 Number 2 Minerals, Microbes, and Remediation
Impact processes are central to the formation and evolution of the Solar System and the modification of planetary surfaces. On Earth, asteroid impacts played a critical role during Earth history; they delivered the constituents of our planet, were responsible for the formation of major ore deposits, and affected life on Earth. Studying impacts and their effects is a very active field at the crossroads of many scientific disciplines, from mineralogy to environmental science. This issue will focus on the mineralogical, geochemical, and petrological aspects of terrestrial impact structures, and in particular on the latest developments in the relevant fields.
Since the dawn of civilization, humankind has been extracting metals and minerals for the production of goods, energy, and building materials. These mining activities have created great wealth, but they have also produced colossal quantities of solid and liquid wastes, known collectively as “mine wastes.” Mine wastes represent the greatest proportion of waste produced by industrial activity. In fact, the quantity of solid mine wastes and the quantity of Earth materials moved by fundamental global geological processes are of the same order of magnitude—approximately several thousand million tons per year. Therefore, the large-scale production, secure disposal, and sustainable remediation of mine wastes represent problems of global significance. Over the past 10–15 years, novel geochemical, mineralogical, microbiological and toxicological techniques have led to a much better understanding of the character, weathering mechanisms, long-term stability, ecotoxicology, and remediation of mine wastes. This issue of Elements will bring readers up to date with these current findings and will highlight new frontiers for mine waste research.
December 2011 – Volume 7 Number 6 Mine Wastes
Karen A. Hudson-Edwards, Heather E. Jamieson, and Bernd G. Lottermoser
From the Vikings’ sunstone to a modern piezometric pressure sensor, tourmaline is an intriguing mineral with a new degree of significance. Tourmaline was considered by 18th century physicists as the key to a grand unification theory relating heat, electricity, and magnetism, but new studies define its role as an indicator of Earth’s processes. With its plethora of chemical constituents and its wide stability range, from near-surface conditions to the pressures and temperatures of the mantle, tourmaline has become a valuable mineral for understanding crustal evolution. Tourmaline encapsulates a single-mineral thermometer, a provenance indicator, a fluid-composition recorder, and a geochronometer. Although also prized as a gemstone, tourmaline is clearly more than meets the eye.
October 2011 – Volume 7 Number 5 Tourmaline
Barbara L. Dutrow and Darrell J. Henry
Partial melting is the most important process affecting the continental crust. It is responsible for the large-scale compositional and density structure that has stabilized the crust over geological time. Partial melting occurs extensively in the deep crustal roots of mountain ranges that form where continents collide. The thin film of melt that develops on the edges and faces of mineral grains results in a substantial weakening of the crust, which concentrates deformation into the melt-bearing rocks and allows them to deform faster. This issue of Elements deals with the source of the heat responsible for widespread melting and the information that can be retrieved from mineral assemblages and microstructures in lower crustal rocks. It also explores the mechanisms of melt transfer and the large-scale geodynamic consequences of melting the crust as it deforms.
August 2011 – Volume 7 Number 4 When the Continental Crust Melts
Edward W. Sawyer, Bernardo Cesare, and Michael Brown
The term water resources refers to natural waters (vapor, liquid, or solid) that occur on the Earth and that are of potential use to humans. These resources include oceans, rivers, lakes, groundwater, and glaciers. The Earth has plenty of water, over 1.4 × 109 km3. However, 97% of global water is saline seawater. Of the 3% that is freshwater, nearly 70% is locked in the polar icecaps and glaciers. The majority of nonglacier freshwater is groundwater (98%). Surface freshwater (rivers and lakes), which has historically served most human needs, constitutes only a small fraction of the Earth’s water resources. Water interacts with minerals, soils, sediments, and rocks, and hence studies of Earth materials have a direct bearing on water resources. Studies of the acquisition, mobility, and fate of elements and isotopes in water provide valuable signatures for tracking water cycles at regional and global scales and are essential for the development of remediation technologies for contaminated water.
June 2011 – Volume 7 Number 3 Global Water Sustainability
Janet G. Hering, Chen Zhu, and Eric H. Oelkers
Iron is the fourth most abundant element at the Earth’s surface. As an essential nutrient and electron source/sink for the growth of microbial organisms, it is metabolically cycled between reduced and oxidized chemical forms. This flow of electrons is invariably tied to the reaction with other redox-sensitive elements, including oxygen, carbon, nitrogen, and sulfur. The end result of these interactions is that iron is intimately involved in the geochemistry, mineralogy, and petrology of modern aquatic systems and their associated sediments, particulates, and pore waters. In the geological past, vast iron sediments, the so-called banded iron formations, suggest that iron played an even greater role in marine geochemistry, and these deposits are now being used as proxies for understanding the chemical composition of the ancient oceans and atmosphere. This issue will explore not only the modern expression of iron cycling but also its record in Earth’s history.
April 2011 – Volume 7 Number 2 Iron in Earth Surface Systems
Kevin G. Taylor and Kurt O. Konhauser
Cosmochemistry is the study of extraterrestrial materials aimed at understanding the nature of Solar System bodies, including the planets, their natural satellites, and small bodies. An important goal is to increase our understanding of the chemical origin of the Solar System and the processes by which its planets and small bodies have evolved to their present states. Research in cosmochemistry covers a wide range of disciplines and techniques, including mineralogy, petrology, major and trace element chemistry, isotope compositions, radiometric ages, magnetism, and radiation-exposure effects. These studies provide a wealth of data about the processes of stellar evolution, planetary system formation, alteration in asteroidal and cometary interiors, and the accretion history of the Earth, including the origin of Earth’s volatile and organic material.
Humanity requires healthy soil in order to flourish. Soil is central to food production, regulation of greenhouse gases, and provision of amenity. But soil is fragile and easily damaged by uninformed management or accidents. One source of damage is contamination with the chemicals that are used to provide the lifestyles to which the developed world has become accustomed. Repairing or cleaning up this damage so that soil can again be used for beneficial purposes is a vitally important task. Traditionally, soil “clean up” involved removing the contaminated soil and replacing it with clean soil from elsewhere. Clearly this is not sustainable. Increasingly researchers and practitioners look to clean up contaminated soil and make it good for reuse rather than simply discarding it. Mineralogy and geochemistry are central to the design and implementation of many of these new approaches.
December 2010 – Volume 6 Number 6 Sustainable Remediation of Soil
During the past decades, thermodynamics has become an essential tool for understanding fundamental processes that have determined the structure and evolution of our planet. From the atmosphere to the ocean and sediments, from metamorphic terranes to magmatic provinces, the lower mantle, and the core, this issue of Elements will illustrate how a better understanding of the manner in which free energy depends on temperature, pressure, and chemical composition allows the Earth’s activity to be better deciphered. At a time when climate change has become a major concern, thermodynamic studies of the atmosphere and ocean have not only an academic interest, but also considerable practical importance.
October 2010 – Volume 6 Number 5 Thermodynamics of Earth Systems
Pascal Richet, Grant S. Henderson, and Daniel R. Neuville
Solid atmospheric particles range in size from a few nanometers to several micrometers and are generated through both natural processes and human activity. Even though these particles are derived from spatially limited source areas and typically become airborne during short-term events, they are ubiquitous globally due to atmospheric circulation. Depending on their physical and chemical properties, these solid aerosols have a major impact on the radiative properties of the atmosphere and glaciers, on cloud condensation, and on the chemical composition of oceans and soils. Because these particles affect transportation and human health, they have recently become the focus of government attention and regulation.
This issue of Elements explores the atmosphere as an exciting new research area for mineralogists and geochemists. It illustrates the most prominent types of atmospheric particles and discuss their key effects on climate and ecosystems worldwide.
August 2010 – Volume 6 Number 4 Atmospheric Particles
Fluids play a critical role during metamorphic processes. They have first-order influence on both reaction kinetics and mass transfer, and thus also on the rate of metamorphism. “Volatile components,” such as H2O and CO2, may strongly influence rock rheology even in the absence of a free fluid phase. Metamorphic fluids therefore control the coupling between chemical reactions, mass transport, and deformation. Microstructures, compositional gradients at various scales, and larger-scale deformation features all reflect the dynamics of fluid–rock interactions. Moreover, the migration of fluids produced during prograde metamorphic processes or consumed during retrogression links metamorphism with the hydrosphere, the atmosphere, and the biosphere. This issue sheds light on the origin of the various patterns that emerge in metamorphic rocks as a response to changes in pressure, temperature, and the composition of pore-filling fluid. By following the metamorphic fluids to or from the Earth’s surface, we also aim to explain how metamorphism may affect our own environment.
June 2010 – Volume 6 Number 3 Fluids in Metamorphism
This issue of Elements focuses on the geochemistry of sulfur in high-temperature, low- temperature, and biogenically mediated processes over a wide range of scales, environments, and time intervals. Sulfur’s multiple valence states (S2- to S6+) allow for its participation in a large variety of geochemical and biogeochemical processes. Sulfur may be one of the light elements contained in the Earth’s core and may have been crucial in core formation. Sulfur is an essential component in all life on Earth. Sulfur geochemistry continues to be used in delineating the early evolution of Earth’s atmosphere and hydrosphere, as a monitor of volcanic SO2 and H2S, and as a tracer of anthropogenic sources. Recent advances in the use of multiple sulfur isotopes (32S, 33S, 34S, and 36S) and in situ isotopic measurements will allow sulfur stable isotopes to develop as vital tracers in the Earth and planetary sciences, with applications to inorganic and biogenic processes.
“Mineral evolution,” the study of Earth’s changing near-surface mineralogy, frames Earth materials research with a historical narrative. This 4.5-billion-year story integrates themes of planetary science, including geodynamics, petrology, geochemistry, thermodynamics, geobiology, and more. Mineralogy thus holds the key to unlocking our planet’s history and assumes its rightful central role in the Earth sciences. The mineralogy of terrestrial planets evolves as a consequence of physical, chemical, and biological processes. Starting with ~12 refractory minerals in prestellar molecular clouds, processes in the solar nebula led to the ~250 different minerals found in meteorites. Initial mineral evolution of Earth’s crust depended on a sequence of geochemical and petrologic processes that resulted in an estimated 1500 different mineral species. Ultimately, biological processes produced large-scale changes in atmospheric and ocean chemistry that may be responsible, directly or indirectly, for most of Earth’s 4400 known mineral species. Mineral evolution thus highlights the coevolution of the geo- and biospheres.
February 2010 – Volume 6 Number 1 Mineral Evolution
December 2009 - Metal Stable Isotopes: Signals in the Environment
During the past decade it has been recognized that the stable isotope compositions of several metallic elements vary significantly in nature due to both biotic and abiotic processing. While this leap in our understanding has been fueled by recent advances in instrumentation and techniques in both thermal ionization and inductively coupled plasma mass spectrometry, the field of metal stable isotope geochemistry has finally moved beyond a focus on development of analytical techniques and toward using the isotopes as source and process tracers in natural and experimental systems. Often termed the “non-traditional stable isotopes,” metal stable isotope systems have found wide application in the geological, hydrological, and environmental research realms and are enjoying a rapidly expanding presence in the scientific literature. This issue of Elements will focus on several intriguing aspects of low-temperature metal stable isotope geochemistry.
December 2009 – Volume 5 Number 6 Metal Stable Isotopes: Signals in the Environment
Thomas D. Bullen and Anton Eisenhauer
Gold fascinates researchers in many sciences. As well as being attractive as a precious metal, gold has important physical and electrical properties that cause it to be an ’advanced material’ for manufacturing and drug delivery in medical science. Geologically, gold can be transported in solution in ambient- as well as high-temperature fluids, and its mineralogy, composition and crystallography are often used to decipher and interpret the genesis of different gold-bearing ore systems. Because gold is a metal, its study requires a detailed understanding of metallography. Finally, nanocrystals of gold and its alloys display unique properties, and these products are finding widespread application in manufacturing and are also seen in the natural environment. This issue of Elements describes new observations about a metal that has fascinated humans since early times. Current research spans the fields of geochemistry, crystallography, and metallurgy, and includes novel studies in the materials sciences.
October 2009 – Volume 5 Number 5 Gold
Robert M. Hough and Charles R. M. Butt
August 2009 - Mineral Magnetism: From Microbes to Meteorites
Magnetic minerals are ubiquitous in the natural environment. They are also present in a wide range of biological organisms, from bacteria to human beings. These minerals carry a wealth of information encoded in their magnetic properties. Mineral magnetism decodes this information and applies it to an ever increasing range of geoscience problems, from the origin of magnetic anomalies on Mars to quantifying variations in Earth’s paleoclimate. The last ten years have seen a striking improvement in our ability to detect and image, with higher and higher resolution, the magnetization of minerals in geological and biological samples. This issue is devoted to some of the most exciting recent developments in mineral magnetism and their applications to Earth and environmental sciences, astrophysics, and biology.
August 2009 – Volume 5 Number 4 Mineral Magnetism: From Microbes to Meteorites
Joshua M. Feinberg and Richard J. Harrison
Most gems are natural minerals, which, although scarce and small, have a major impact on society. Their value is directly related to proper identification. The determination of the species is key, of course, and must be done non-destructively. This is where classical tools of mineralogy come into play. However, other issues are paramount: Has this gem been treated? Is it natural or was it grown in a laboratory? For certain varieties, being able to tell the geographical provenance may enhance value considerably. These issues necessitate cross-linking the formation of gems with their trace-element chemistry. These unusual mineralogical and geochemical challenges make the specificity of gemology, a new and growing science, one of the possible futures of mineralogy.
June 2009 – Volume 5 Number 3 Gems
Emmanuel Fritsch and Benjamin Rondeau
Of all naturally occurring clays, bentonites are arguably the most interesting, versatile and useful. This issue of Elements describes how these fascinating materials occur and how they are used in all manner of applications. Composed predominantly of swelling minerals (smectites) and formed mainly from the alteration of volcanoclastic rocks, bentonites are used by geologists for stratigraphic correlation. Bentonite deposits are mined worldwide as they are commercially very valuable. Because of their physicochemical properties, bentonites are used in a wide variety of industrial applications, including the drilling industry, foundries, civil engineering, adsorbents, filtering, etc. Recent formulations of polymer–smectite nanocomposites have been used in industry to make new materials with amazing properties and diverse applications. Bentonites play an important role in the protection of the environment from industrial waste and pollutants and have also been used in medical applications in human health.
April 2009 – Volume 5 Number 2 Bentonites - Versatile Clays
February 2009 - Scientific Exploration of the Moon
Our current understanding of the Moon’s history, interior structure, and chemical composition is based in large part on geochemical data acquired from samples from the U.S. Apollo and Soviet Luna missions; data acquired by Apollo geophysical instruments; orbital geochemical and spectral data acquired by robotic missions from the U.S., Japan, and China; analysis of lunar meteorites derived from previously unsampled regions of the Moon; and Earth-based radar observations and infrared spectral reflectance data. All of these efforts have contributed to a preliminary understanding of the origin of the Moon and the processes that have affected its surface and interior. Isotopic analyses of impact-generated samples have placed constraints on the time-dependent meteorite flux that not only affected the Moon but also the Earth and other objects in the inner solar system. In this issue of Elements, leading scientists discuss the major concepts that underpin our current understanding of the Moon, as well as scientific plans for international scientific exploration by robotic and human missions.
February 2009 – Volume 5 Number 1 Scientific Exploration of the Moon
At first glance, nano and Earth seem about as far apart as one can imagine. Nanogeoscience seems to be a word connecting opposites. More specifically, a nanometer relative to a meter is the same as a marble relative to the size of this planet. But to a growing number of Earth scientists, the term nanogeoscience makes perfect sense. Nanomaterials can be manufactured, but they are also naturally occurring. In fact, we now think that nanomaterials are essentially ubiquitous in nature. Importantly, nanomaterials often have dramatically different properties from those of the same material with larger grain size. By understanding these property changes as a function of size and shape in the nanorange, we will acquire another perspective from which to view Earth chemistry.
This issue of Elements explores our current knowledge of nanogeoscience using numerous examples from the “critical zone” of the Earth, as well as from the oceans and the atmosphere. Important insights into local, regional, and even global phenomena await our understanding of processes that are relevant at the smallest scales of Earth science studies. Nanogeoscience is at a relatively early stage of development. Therefore, large gaps in our knowledge in this area exist, making the next few years and decades an exciting time of new realizations, discovery, and change. This issue of Elements will help promote and energize this field in its early adolescence.
Storage of carbon in the subsurface involves introduction of supercritical CO2 into rock formations beneath the surface of the Earth, typically at depths of 1000 to 4000 meters. Although CO2 is a relatively benign substance, the volume being considered is large. If developed to its envisaged potential, geologic sequestration will entail the pumping of CO2 into the ground at roughly the rate we are extracting petroleum today. To have the desired impact on the atmospheric carbon budget, CO2 must be efficiently retained underground for hundreds of years. Any underground storage system will have to account for the natural characteristics of subsurface formations; some are advantageous for storage while others are not. When foreign materials are emplaced in subsurface rock formations, they change the chemical and physical environment. Understanding and predicting these changes are essential for determining how the subsurface will perform as a storage container. The specific scientific issues that underlie sequestration technology involve the effects of fluid flow combined with chemical, thermal, mechanical, and biological interactions between fluids and surrounding geologic formations. Complex and coupled interactions occur both rapidly as the stored material is emplaced underground, and gradually over hundreds to thousands of years. The long sequestration times needed for effective storage and the intrinsic spatial variability of subsurface formations provide challenges to both geoscientists and engineers. A fundamental understanding of mineralogical and geochemical processes is integral to this success.
October 2008 – Volume 4 Number 5 Carbon Dioxide Sequestration
The geoscientific and economic significance of the PGE is immense. Due to their extreme siderophile and chalcophile behaviour, the PGE are highly sensitive tracers of geological processses involving metal and sulfide phases. Furthermore, there are two radioactive decay series involving PGE, which combine both lithophile and chalcophile characteristics in various parent or daughter elements. PGE consequently offer insight into a wide range of geological processes that no other group of elements can provide. The PGE are also very important economically, primarily due to their “noble” character in common applications such as jewelry, electrodes, catalysts, and fuel cell technology. Unfortunately, the PGE are also bioavailable as potential toxins to organisms in the natural environment. Their widespread use, particularly in automotive catalytic converters, makes their environmental behavior a matter of increasing concern. This issue of Elements will provide an overview of our current understanding of the distribution of PGE and their isotopes in the Earth and solar system, and what this knowledge tells us about the workings of our planet, about extraction of PGE resources, and about the environmental risks attendant on their use.
August 2008 – Volume 4 Number 4 Platinum-Group Elements
The field of high-pressure mineral physics is central to our understanding of the Earth’s interior and its evolution. It is also a field that is rapidly advancing. Recent major discoveries, such as the post-perovskite phase transition that may explain some of the properties of the core–mantle boundary, speak to the continued importance of high-pressure mineral physics experiments. The results from experimental mineral physics along with seismological data are used to construct compositional and thermal models of the Earth and its heterogeneity, including inferences of deep geochemical reservoirs. These results are also key to understanding all planetary bodies in the solar system. This issue of Elements will highlight several key areas of high-pressure mineral physics in a form that is accessible to a broad mineralogical audience.
June 2008 – Volume 4 Number 3 Deep Earth and Mineral Physics
Phosphorus is a unique element: it is essential to the existence of all living forms, and as such controls biological productivity in many terrestrial and marine environments; but when in excess, it leads to uncontrollable biological growth and water-quality problems. This has become a common environmental issue, resulting from our careless use of phosphorus in agriculture, yet phosphate ore deposits, from which fertilizers are produced, are a finite natural resource. Understanding the properties of phosphate minerals may hold the key to protecting the future of this resource. Phosphate minerals are also of extreme importance in biomineralization and could be the future hosts of nuclear waste. Despite all this, mineralogists and geochemists have invested little time understanding phosphate mineral stability, reactivity, and transformations, and this issue attempts to bring phosphates to the forefront of our scientific endeavors.
April 2008 – Volume 4 Number 2 Phosphates and Global Sustainability
Eugenia Valsami-Jones and Eric H. Oelkers
Explosive super-eruptions from large-volume, shallow magma systems lead to enormous and devastating pyroclastic flows, the formation of gigantic collapse calderas, and deposition of volcanic ash over continent-sized areas. Recognition that future eruptions from these “supervolcanoes” will undoubtedly have severe impacts on society—and perhaps on life itself—has led to recent public and media interest. Should we be concerned about an imminent super-eruption? The answer to this question requires an understanding of past eruption events. In this issue, geoscientists investigating ancient supervolcanoes provide insight into the processes and the time required to generate large volumes of eruptible magma, the monitoring of a youthful system, and super-eruption processes and consequences.
December 2007 - Medical Mineralogy and Geochemistry
Medical mineralogy and geochemistry is an emergent, highly interdisciplinary field concerned with both normal and pathological interactions between minerals or amorphous inorganic solids and biomolecules or cells within the human body, and the transport and fate of prions and protein toxins in the soil environment. Prior research has, appropriately, focused on the complex genetic and molecular biological aspects, but there is a growing recognition of the vital need for understanding the surface and bulk properties and reactivities, especially at the challenging nanoscale characteristicof biomacromolecules and biominerals. Geochemists and mineralogists are uniquely trained to contribute to this new field because of their knowledge of mineral stability, surface reactivity, mineral precipitation/dissolution kinetics, and mineral–sorbate interactions, as well as their ability to study complex systems using state-of-the-art spectroscopic and microscopic techniques.
December 2007 – Volume 3 Number 6 Medical Mineralogy and Geochemistry
The Critical Zone (CZ) encompasses all fluid, mineral, gaseous, and biotic components from the outer envelope of vegetation down to the lower limit of groundwater. It supports much of life on Earth. Important societal relevant challenges related to CZ science to be addressed in the next decade are: (1) what processes control fluxes of carbon, particulates, and other reactives gases into and from the CZ? (2) how do weathering processes in the CZ nourish ecosystems? (3) how do chemical and physical weathering processes shape the CZ? and (4) how do biogeochemical processes in the CZ govern long-term sustainability of water and soil resources?
October 2007 – Volume 3 Number 5 Critical Zone: Where Rock Meets Life
Susan L. Brantley, Timothy S. White, and K. Vala Ragnarsdottir
August 2007 - Frontiers in Textural and Microgeochemical Analysis
Recent advances have been made in high-resolution in situ methods to image mineral growth patterns, analyse compositional and isotopic zonation, and improve our ability to visualize, study, and model rock textures in three dimensions. These advances provide a significant step forward in the understanding of how rocks form and the history they can tell us. Computer-aided reconstructions and 3D modelling of textures, advanced models of crystallisation and very high-resolution sampling of within-crystal geochemical variations are at the frontiers of current studies in igneous petrology. This thematic issue will highlight the integration of textural and geochemical information as a powerful tool in the understanding of igneous rocks, and will provide examples that researchers in other disciplines may use to further advance their studies.
August 2007 – Volume 3 Number 4 Frontiers in Textural and Microgeochemical Analysis
Dougal A. Jerram and Jon P. Davidson
The issue of energy resources in the future will be one of the most important in the 21st century. Future climate change and the ways to abate it while still supplying needed energy will impact future political relations, world economics, human health, and the environment. Earth scientists have much to add to the debate, but are often not heard. This issue will provide a geologic perspective on some of the issues and offer some potential solutions to the problems. Detailed discussions include issues of climate change, geologic sequestration of carbon dioxide from fossil fuel plants, natural gas resource expansion via methane hydrates, and the potential uranium resource for nuclear energy.
June 2007 – Volume 3 Number 3 Energy: A Geoscience Perspective
April 2007 -- On the Cutting Edge: Teaching Mineralogy, Petrology, and Geochemistry
New advances in research on learning have important implications for teaching mineralogy, petrology, and geochemistry. Effective instructional practices are increasingly student centered, address diverse student learning styles, and employ a variety of active-learning strategies. Teaching practices should be redirected from learning about science to learning to be scientists, emphasizing inquiry, discovery, critical thinking, problem solving, and the skills required to observe, analyze, and interpret the world around us. This issue of Elements describes some of these findings and provides examples of how they can be applied to teaching mineralogy, petrology, and geochemistry.
April 2007 – Volume 3 Number 2 On the Cutting Edge: Teaching Mineralogy, Petrology, and Geochemistry
Where would Earth science be without zircon? As Earth’s timekeeper, zircon has proven to be a remarkable and versatile mineral, providing insights into deep time and ancient Earth processes. However, there is still much to learn about Earth’s history from zircon and its behaviour. Zircon cannot be treated simply as a passive “safehouse” of stored isotopic and chemical information but must instead be interpreted carefully, in its petrological, mineralogical, and geological contexts, and in the light of all possible lines of evidence. Zircon has been a wonderful servant in our quest to unravel the history of the Earth—and has so much more to offer as we unlock the secrets of its chemical and physical responses to the processes operating in the Earth.
February 2007 – Volume 3 Number 1 Zircon - Tiny but Timely
This issue will discuss critical issues of nuclear power (nuclear waste and nuclear weapons proliferation) and the required scale of nuclear energy if it is to have a significant impact on reduced CO2 emissions. Each of the four principal types of “waste” that result from the nuclear fuel cycle will be examined.
December 2006 – Volume 2 Number 6 The Nuclear Fuel Cycle: Environmental Aspects
October 2006 - Glasses and Melts: Linking Geochemistry and Materials Science
Melts play a fundamental role in determining the physical and chemical behaviour of magmas and processes in the deep Earth. However, due to the inherent difficulties associated with working at high temperatures, much of the geological research over the last 30 years has used quenched melts or glasses as proxies for melts themselves, as it is assumed that the structure of glass resembles that of melt. Many of the advances in glass science and our understanding of glasses as materials, have come about due to geological researchers.
October 2006 – Volume 2 Number 5 Glasses and Melts: Linking Geochemistry and Materials Science
Georges Calas, Grant S. Henderson, and Jonathan F. Stebbins
The past decade has seen exciting new evidence and understanding of the first billion years of Earth history. This time period has formerly been considered the “dark ages” due to the rarity of preserved samples. Progress has been facilitated by new theory, new samples, and new technology allowing investigation of new isotope systems, smaller sample sizes, and in situ analysis. These studies combine mineralogy and geochemistry with disciplines as diverse as meteoritics, atmospheric physics, and biology.
During the past several decades, a shift of a substantial quantity of scientific real estate has occurred, as spacecraft data have transformed the planets from astronomical objects into geologic worlds. Mars is the current focus of planetary exploration, and NASA’s objectives for this effort are based on the theme, “follow the water.” This issue will address new discoveries from spacecraft and from Martian meteorites about where water or ice was (or is) located, and new insights into the role of water in determining the mineralogy, petrology, and geochemistry of the Martian surface.
Arsenic is an element known throughout history as a classic poison. Currently, very small but highly significant concentrations of this element in drinking water supplies are causing massive health problems to many millions of people in some of the world’s poorest nations, and more localised sources related to mining and processing are also a concern. A review of background information on arsenic chemistry, occurrence in the Earth, production and uses, as well as its toxic properties, leads in to the other articles in this issue of Elements.
February 2006 -- User Research Facilities in the Earth Sciences
Earth scientists rely on effective access to user research facilities that provide state-of-the-art analytical instrumentation. This thematic issue will focus on these facilities and how to use them including scientific impact, descriptions of facilities and analytical techniques currently available, procedures for gaining access to perform experiments, factors that enable effective usage, and a look to the future, particularly in terms of how Earth scientists can best take advantage of new research facilities currently under design and construction.
February 2006 – Volume 2 Number 1 User Research Facilities in the Earth Sciences
December 2005 -- Large Igneous Provinces: Origin and Environmental Consequences
Large igneous provinces record major outpourings of igneous rocks, both on the continents and in ocean basins. Their origin is still vigorously disputed, with models invoking mantle plumes, thermal effects of the lithosphere, and meteorite impacts. The environmental consequences are also hotly debated: some argue that voluminous flood basalt volcanism triggered catastrophic changes to the global climate and mass extinctions, whereas others believe their effects to be much less significant. Six contributions by experts in their respective fields outline the various models for the formation of LIPs and summarise the ideas about the environmental consequences of such massive and prolonged volcanism.
December 2005 – Volume 1 Number 5 Large Igneous Provinces: Origin and Environmental Consequences
September 2005 -- Toxic Metals in the Environment: The Role of Surfaces
Metals are prevalent in the environment. They are derived from both natural and anthropogenic sources. Certain metals are essential for plant growth and for animal and human health. However, at excessive levels they are toxic. Metals undergo an array of processes, including sorption/desorption, precipitation/dissolution, and oxidation/ reduction, with reactive natural surfaces such as clay minerals, metal oxides, humic substances, plant roots, and microbes. These biogeochemical processes control the solubility, mobility, bioavailability, and toxicity of the metals. This issue of Elements will explore research frontiers in the areas of metal mobility and reaction mechanisms on natural surfaces. These advances will be explored at multiple scales, using state-of-the-art analytical techniques.
September 2005 – Volume 1 Number 4 Toxic Metals in the Environment: The Role of Surfaces
Few scientific questions so capture the public imagination, or provoke such lively debate, as how life on Earth emerged. In the next issue of Elements, four of the most creative minds in origins research present their original insights on the geochemical origins of life. Each author has studied the field in depth, and each has come to an inescapable conclusion: rocks and minerals must have played a pivotal role in the transition from the blasted, prebiotic Earth to the living world we now inhabit. Rocks and minerals catalyzed the synthesis of key biomolecules; they selected, protected and concentrated those molecules; they jump-started metabolism; and they may even have acted as life’s first genetic system.
June 2005 – Volume 1 Number 3 Genesis: Rocks, Minerals, and the Geochemical Origin of Life
Diamond, the fascinating ultrahard mineral, is the focus of considerable interest and scientific research. Recent advances particularly relevant to geoscientists include: diamond as a recorder of Earth processes from the perspective of inclusions, chemistry, and conditions of formation; synthesis for research applications and processing to modify color and physical properties, important to diamond gems and anvils; the implications of nanodiamonds from meteorites.
Water and other geofluids play an important role in the geochemical and rheological evolution of the Earth and other bodies in the solar system. These fluids are responsible for the formation of hydrothermal mineral deposits, affect eruption behavior in volcanic systems and the geophysical properties of the mantle, and significantly affect the way in which rocks deform and fracture. Water is required for life to develop and survive, and the search for life beyond Earth defaults to a search for water in the solar system. In this inaugural issue of Elements, current knowledge concerning the distribution and role of water in diverse geological processes and environments is considered.
January 2005 – Volume 1 Number 1 Fluids in Planetary Systems
Robert J. Bodnar
Rodney C. Ewing, Michael F. Hochella, Jr., and Ian Parsons