The bulk of the cave formations that are seen in the caves are formed from calcite. Calcite is the most common crystaline form of the mineral calcium carbonate. As water seeps into a cave it carries with it dissolved calcium carbonate. As the water is exposed to the atmosphere within the cave it is able to release carbon dioxide as well as evaporate slightly. The result of this is to cause calcite to start to precipitate.

Calcite is relatively soft, rating 3 on Moh's hardness scale. This means that if it was any softer it would be possible to scratch it with a fingernail. For this reason it is very important that visitors to caves do not touch the formations as it is very easy to wear the surface away.

Although the usual colour for calcite is white mineral impurities will cause the crystal to adopt other colours. Yellows, reds and browns are commonly created due to the presence of muds or concentrations of iron oxide. Touching calcite allows oils from the skin to penetrate the crystal structure turning it black. A common mistake is to say that the water hardens. This is incorrect - afterall hard water would be ice and since the caves are around 17 degrees Celsius ice formations would quickly melt.