No other species in Earth’s history has left a mark on the planet as profound and lasting as Homo sapiens. So much so that scientists are increasingly making a case for designating a new geological time period: the Anthropocene. In a paper published this month in the journal American Mineralogist, two UA scientists lend further merit to this idea by identifying for the first time a group of 208 mineral species that originated either principally or exclusively because of human activities.