Diamonds in Ureilites: The Never Ending Story

Diamond is the most illustrious of all minerals. Made of pure carbon atoms packed into a dense isometric structure, diamond is treasured as a gemstone for its brilliant (adamantine) luster and supreme hardness, and is in demand for many industrial applications because of these same properties. On Earth, most natural diamonds form deep (>160 km) under continental cratons, where high static pressures (>45 kilobars) stabilize diamond relative to graphite, which is the low-pressure polymorph of pure carbon. Such diamonds are only fortuitously brought to the surface, carried as xenoliths or xenocrysts in explosive volcanic pipes known as kimberlites. To geoscientists, diamonds provide invaluable records of the extreme conditions and otherwise inaccessible environments in which they formed. Diamonds can also probe exotic extraterrestrial environments. Nanometer-sized diamonds also occur as a rare component of the most primitive carbonaceous chondrite meteorites, rocks which preserve the original components of the Solar System.

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v17n4 From the Editors

For centuries, philosophers and scientists had proposed the existence of planets outside of our own Solar System. Yet, it wasn’t until late 20th century that scientists first confirmed the existence of exoplanets. How does one study planets that are thousands of light years away from Earth? Exoplanet studies are not purely within the domain of astrophysicists. As you will discover in the articles of this issue, exoplanet research requires an interdisciplinary approach.

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People in the News: Rieder Retires

Milan Rieder is one of those tireless heroes of the publishing world. Since 1977, Milan has been Editor of Physics and Chemistry of Minerals, published by Springer Nature, and now, in 2021, he has finally decided to retire.

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Vectors, Scalars, and How Science Works

The Oxford English Dictionary defines ‘vector’ as a quantity having direction as well as magnitude, and ‘scalar’ as a quantity having only magnitude, not direction. Much geological research starts with fieldwork, manifestly a vector activity. In Figure 1A, the geologists are exploring the intersection of a complex, 3-D body, the layered Klokken syenite, a 4 × 3 km igneous intrusion in the Gardar alkaline province of SW Greenland, with a mountainous 3-D land-surface. I described the unusual layering in Elements v10n1 (Parsons 2014). The igneous rocks were emplaced 1,166.3 ± 1.2 million years ago, and the 650 m of 3-D topography, which reveals the inner workings of the magma chamber, was carved by the advance and retreat of the mighty Greenland ice sheet in the last few thousand years. Only the age (a U–Pb age from baddelyite, ZrO2) is a scalar quantity.

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Silicon Carbide Dust? The Answer is Blowin’ in the Wind

Silicon carbide (SiC) minerals, which were argued to condense in stellar winds, were first isolated and imaged in 1987 (Bernatowicz et al. 1987). However, their existence in meteorites had been speculated from extensive noble gas studies. These studies suggested that SiC minerals are the carrier phases of the exotic 128,130Xe and 22Ne isotopic anomalies that can be found in primitive meteorites (e.g., Anders and Zinner 1993). In fact, SiC stardust does carry large isotopic anomalies, up to 4 orders of magnitude, both in light mass elements (e.g., carbon, nitrogen) and in medium mass elements (e.g., magnesium, iron, titanium). These anomalies can only be produced in stars through nuclear reactions occurring at extreme temperatures, by which the structure of the atomic nucleus is altered. The extreme isotopic anomalies in the SiC dust grains were not completely homogenized during the first 10 million years of planet formation and Solar System evolution, so they have kept their compositions intact until today. The dust grains carrying these enormous anomalies can be identified in extraterrestrial rocks that fall to Earth.

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Diversity among Editorial Boards of Elements and other selected Geochemistry, Cosmochemistry, Mineralogy and Petrology journals

The publication of scientific work is foundational to our disciplines. To ensure equitable publication standards during the global flow of knowledge production, professional societies and publishers must take positive steps to avoid biases that might hinder the publication of scientific work (see Liévano-Latorre et al. 2020). Biases among editors and reviewers can be unconscious and be influenced by different aspects of an author’s identity: country of origin, first language, affiliation, gender identity, ethnicity, and/or other factors. These biases could result in challenges to publication rates and visibility in key journal forums for under-represented groups (Lerback et al. 2020). Ensuring that there is diversity in the peer review and publishing process, and on editorial boards, may help to eliminate bias.

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v17n3 From the Editors

In just about every physical science course the concept of the atom is taught. Students are introduced to the three subatomic particles of electrons, protons, and neutrons. Usually, there is a lot of emphasis on electrons, because their configuration determines the chemical properties of an atom. And the protons get a lot of attention as well: who doesn’t like H+? Sadly, too often, neutrons are left in the “Oh, there is another part of an atom” category … that neutral subatomic particle that adds weight to the atom.

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Nature’s Underground Libraries

The city of Oxford (UK), where I have relocated since my last editorial, is a provincial metropolis of some 150,000 souls about 90 km northeast of London. Oxford is famous for its ancient collegiate university, with colleges dating back to 1096. The University of Oxford is slightly less well-known for its remarkable Bodleian Library, created in its present form in 1598 by Sir Thomas Bodley. It is one of just six copyright libraries in Britain and Ireland. A copyright library (or ‘library of legal deposit’) is one that, since 1662, has the right to request and store for posterity a copy of every new work published in English. As you can imagine, one copy of every book published in English amounts to quite a few books over the years. The challenge for any of the copyright libraries is where to store them all. For the Bodleian, in the spirit of the iceberg, the answer lies under the surface, where a substantial fraction of its 13 million print items is stored in vast underground vaults.

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