Gypsum formations form in a similar way to calcite speleothems. Gypsum is a mineral, with the chemical formula CaSO4· 2H2O. Basically, it is calcium sulfate with some water attached. Gypsum can take forms known by cavers as snow, flowers, crust, needles, and hairs, depending on the shape. There are no gypsum formations along the tour route, but there are many in the Gypsum Annex. They tend to be white (or colorless), small, and very fragile.