Editorials

The concept of oxidation as the process that turns iron metal into rust is familiar to all of us. We might be equally familiar with reduction, the “reverse” of oxidation, by which iron metal is produced by heating iron ore with coke in a blast furnace. Rusting and smelting of iron are just two examples of reduction–oxidation (“redox”) reactions. As one species (e.g., the iron ore) becomes reduced, so the other (e.g., the coke) becomes oxidised. In redox, there is always something being oxidised and something else being reduced; it’s the yin and the yang of geochemistry, as the guest editors of this issue of Elements refer to it (cover).

This past year has seen the departure of many of our great colleagues who shaped the fields of mineralogy, petrology, and geochemistry. They were part of our extended academic family and will be greatly missed. Although their academic contributions can be found in their curriculum vitae and scientific publications, their personal histories, the things that shaped their lives and careers, are more elusive. However, personal histories, where published, can capture the “human” aspect behind the scientist and include stories filled with happiness and humor, hardship and perseverance, and, above all, serendipity.

I would like to know, now that we’ve reached the year 2020, where is the hydrogen economy I was promised? Hydrogen fuel cell cars lurk at the margins of the marketplace, and several governments and corporations continue to make large bets on hydrogen’s future, but as I look out the window at my battery assisted, hybrid car, I’m still left wondering “what went wrong”?