Cave of the Mounds the Interior and the National Park Service. To be considered a NNL, "a site must be one of the best examples of a natural region's characteristic biotic or geologic features." Cave of the Mounds is home to many varieties of speleothems. As with most caves, stalactites and stalagmites are common. Formations found inside the cave include: These formations come in many different brilliant colors such as reds, browns, blues, and grays. The reds and browns are caused by the presence of iron oxide in the formation. Similarly, blues and grays are caused by manganese oxide. Some speleothems are even partially
Cave of the Crystals much smaller, with small "cauliflower" formations and fine, threadlike crystals. All of the caves discovered are: Cave of Crystals, Queen's Eye, Candles Cave, Ice Palace and Cave of Swords. A scientific team coordinated by Paolo Forti, specialist of cave minerals and crystallographer at the University of Bologna (Italy) explored the cave in detail in 2006. To survive and to be able to work in the extreme temperature and humid conditions which prevent prolonged incursion in the crystal chamber, they developed their own refrigerated suits and cold breathing systems (respectively dubbed Tolomea suit and Sinusit respirator). Special caving overalls were fitted