Indiana Caverns the calcium carbonate precipitates out of the water. The calcium carbonate, in the form of the mineral calcite, a solid, crystallizes onto the bottoms and sides of existing stalactites, stalagmites, helictites, and sheets of flowstone to grow the formations over time. Other minerals are brought into the cave by flowing of water to create white, red, tan, and gray colors on the formations and walls. St. Louis Limestone is primarily made of calcite, but is also known to contain magnesium sulfate, manganese dioxide, ferric oxide, gypsum, dolomite, and aragonite. On the show tour, deposits of calcite, manganese dioxide, and ferric
Calcium carbonate contains calcium atoms coordinated by 6 oxygen atoms, in aragonite they are coordinated by 9 oxygen atoms. The vaterite structure is not fully understood. Magnesium carbonate MgCO has the calcite structure, whereas strontium and barium carbonate (SrCO and BaCO) adopt the aragonite structure, reflecting their larger ionic radii. Calcite, aragonite and vaterite are pure calcium carbonate minerals. Industrially important source rocks which are predominantly calcium carbonate include limestone, chalk, marble and travertine. Eggshells, snail shells and most seashells are predominantly calcium carbonate and can be used as industrial sources of that chemical. Oyster shells have enjoyed recent recognition as a