s. It is a type of dripstone. Formation and type Stalactites are formed by the deposition of calcium carbonate and other minerals, which is precipitated from mineralized water solutions. Limestone is calcium carbonate rock which is dissolved by water that contains carbon dioxide, forming a calcium bicarbonate solution. The chemical formula for this reaction is: » : + + → This solution travels through the rock until it reaches an edge and if this is on the roof of a cave it'll drip down.… (More on Stalactite)