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
Blombos Cave terrain abruptly drops down towards shoreline that lies some 34,5 meters below the cave entrance. The talus, which primarily consists of Middle Stone Age deposit, rock fall and unconsolidated sediments, is stabilised by an area of large, exposed blocks (14m²). At some stage - and in between the prehistoric occupation of the cave site - these blocks have fallen down from the rock face above, effectively preventing site erosion and allowing sediments to stabilize and accumulate in front of the cave's drip line. Calcium carbonate (CaCO3) rich ground water seeps in from the cave roof and percolates through the interior