| Cavern speleothems (cave deposits, such as these stalagmites) consist of the mineral calcite (CaCO3) that precipitates from groundwater that enters a cavern and evaporates into the air. Accumulations of calcite deposits form the rock called travertine (a variety of limestone deposited in freshwater environments). Other minerals, including oxides of iron and manganese, clay minerals, and organic matter stain travertine speleothems and cavern walls, giving the rock a variety of colors other than the typical white of pure calcite-rich travertine. Some speleothems are also composed of aragonite and gypsum (Davis, 2000; NPS, 2009; NPS, 2010]. |
