The Illinois State Geological Survey (ISGS) manages one of the largest collections of geologic samples in the United States. The collections are housed in the Geological Samples Library (GSL), located in the Natural Resources Studies Annex on the campus of the University of Illinois at Urbana-Champaign. The Geological Samples Library is the legislatively mandated repository for drill-hole samples in Illinois (State Law 225 ILCS 730/2), including cores drilled for mineral exploration and geologic investigations.