THE IRONY OF IRON – LIFE’S MAJOR TRACE ELEMENT
By Friedhelm von Blanckenburg | December, 2018
All organisms, from lowly microbes to higher forms of life (including humans), need iron. Yet there is irony to iron. Despite being the second most abundant element in the Earth, it is not readily available for consumption. Earth owes this irony to the combined effects of geodynamics and biology. The early segregation of iron into the Earth’s core relegated iron to “only” the fourth most abundant element in the crust. About 2.3 billion years ago, a complex interplay between photosynthesis and redox changes in Earth’s mantle allowed the buildup of free atmospheric oxygen. Today, there is a sufficient supply of photosynthetic oxygen to convert all iron at the Earth’s surface and in its surface waters, including seawater, into its ferric [Fe(III)] form. This ferric form is barely soluble, making it hard to access by organisms. Ironically, life itself made iron a ‘trace element’.
THE “PLASTICENE” EPOCH?
By Nancy Ross | October, 2018
This issue of Elements explores the fascinating realm of deep-ocean deposits that have the potential to provide society with many of the raw mineral resources required to meet the world’s growing needs. While raw materials have always, and always will, play a critical role in meeting these demands, materials made by humans have also become increasingly important, expanding in concert along with the world’s population, industry, and resource use. Most notably, plastics, which are synthetic organic polymers derived from fossil hydrocarbons, have become an indispensable part of our material world because of their remarkable number of uses and versatility. Plastic bottles, bags, credit cards, scotch tape, pipes, toys, to name a few, form part of our everyday life. Not surprisingly, the global production of plastic has increased from 2 metric tons (Mt) in 1950 to 380 Mt in 2015 (Geyer et al. 2017).
ETHICALLY SOURCED METALS
By Jon Blundy | August, 2018
The Central Andes is a land of llamas, salt flats and majestic volcanic peaks. It is one of most remote places on Earth and arguably the driest. In a not unconnected way, the Central Andes is also home to the world’s largest copper mines. The unique combination of magmas, tectonics and climate, described in this issue of Elements, has conspired to create hydrothermal ore deposits that provide a third of the world’s copper and a quarter of its molybdenum (see “Ore Deposits of the Central Andes” by Lluis Fontbote on page 257).
THE MAKING OF GREAT WINE
By Bernard J. Wood | June, 2018
As we set up the publication schedule for each year, the principal editors of Elements try to ensure that the journal maintains enough diversity to hold the interest of you, our readers. In this context, we sometimes accept proposals for issues on very well-known mainstream subjects (such as layered intrusions) which we think can usefully be updated and summarized at a good level. We also try, however, to bring you subjects which are outside the mainstream yet still can be grouped loosely within the areas of geochemistry, mineralogy and petrology. That is how we categories the current issue dealing with the environmental aspects of making high quality wine.
THE EXCITEMENT OF SCIENCE DISCOVERIES IN THE BLUE SKY
By Friedhelm von Blanckenburg | April, 2018
The articles in this “Comets” issue of Elements provide a fascinating account of comets and the making of our planetary system. We learn why comets are visible to the naked eye and about their complex organic geochemistry, the surprising find of free O2, and the likelihood of a comet impact on Earth. Perhaps most impressively, we learn about the tremendous effort that goes into the exploration of comets. These missions require decades of design, planning, and instrument miniaturization and their culmination captures our imagination in a way little else can. Who could not be enthralled by the evocatively named Stardust mission returning a few thousand grains of dust from comet Wild 2 to Earth? We collectively shared the despair when communication was lost from Rosetta’s Philae lander on comet 67P/Churyumov–Gerasimenko, and the excitement about the unparalleled wealth of information sent back during its 70 hours of life on the comet’s surface.
FOOD FOR GEOLOGICAL THOUGHT
By Nancy L. Ross | February, 2018
I recently asked a first-year student what the difference was between a rock and a mineral and he replied, “A rock is like a salad…” His immediate reply started me thinking about using food analogues to teach geological concepts. I subsequently found this approach has been widely studied and proven to be effective. For example, Baker et al. (2004) used the viscosities of common foods as analogues for silicate melts to help teach students about igneous processes.