WHY NATURALLY-OCCURRING NANOPARTICLES ARE IMPORTANT IN UNDERSTANDING HOW EARTH WORKS: A TRIBUTE TO BENJAMIN GILBERT

It has been a half-century since deviating properties of minerals in the nanometer size range were first recognized in a modern scientific sense, but the critical mass of pioneering scientists was not realized, and this branch of geoscience did not flourish. It has only been in the last decade that this field has finally gained momentum and is in fact now growing exponentially, driven in large part by new young visionaries like Ben Gilbert. Dr. Gilbert and others have shown how and why the structure, properties, and the resulting expressed reactivity of mineral nanoparticles, generally speaking, vary from their bulk cousins, as do most other materials studied in this size range. In addition, they have discovered more and more about the peculiarities of nanominerals, and at the same time recognized new species of nanominerals. But the devil is in the details of structure/property/size-shape relationships, and they are highly challenging to elucidate. Beyond this, are these relationships materials science curiosities, or in fact key to the workings of major Earth systems? Simply put, is all this truly important to Earth science in a board and fundamental sense, and if so, exactly in what ways?

Multiple examples will be given in this presentation of how recent discoveries have made nanominerals, mineral nanoparticles, and the so-called indirect incidental nanoparticles (another recently recognized naturally-occurring nanomaterial) a central, critical theme in understanding the atmosphere (from global climate change to respiratory disease), the lithosphere (from the critical zone to the mantle), the hydrosphere (from ocean composition and biogeochemistry to pollutant transport in groundwater), and even extraterrestrial materials (from Martian soils to interplanetary and interstellar dust). In addition, geologic processes that have rarely, if ever, been considered to have nanoscience connections, such as ore deposit formation and shallow to deep-Earth fault generation and earthquake mechanics, have now been shown to be clearly related to nano-properties and processes. In all cases, the fascinating structure/property/size-shape relationships of these naturally-occurring nanomaterials are central to understanding all of the key roles that they play on Earth.