At the blurry edge of mineralogy

Nanominerals are characterized by crystal dimensions that fall between 100 and 1 nm, and as the length scale of atomic ordering approaches the lower end of this range, a material's physical and chemical properties may dramatically diverge from what is observed at the macroscale. Indeed, when atomic correlation lengths approximate the dimensions of the unitcell, one can reasonably ask whether a natural material should be classified as a mineral at all. In their Outlook contribution, Caraballo et al. (2014) offer a state-of-the-art assessment of the science of environmental nanominerals, with an emphasis on the role that crystallinity plays in their behavior.