The Fort Stanton-Snowy River cave system (FSC) is located in Lincoln County, New Mexico in the upper Rio Hondo Basin. The entrance of the cave is on Bureau of Land Management (BLM) land near the site of historic Fort Stanton. In 2001, the Snowy River Formation was discovered. This formation, a white calcite deposit that lines a streambed within the cave, is now considered to be the largest cave formation in the world. Initially thought to be hydrologically inactive, the Snowy River passage has intermittently flooded in response to large precipitation events such as the passage of Hurricane Dolly in 2008 and a large spring snowmelt runoff in 2010. There is interest in determining the source of the water that flows through the cave and deposits the Snowy River Formation. These data represent the rock chemistry from the geologic units surrounding the cave and chemistry from a calcite core drilled into the Snowy River Formation.