Final answer:
Stalactites are formed from dripping mineral deposits on cave ceilings, and stalagmites form on the ground below them. Both consist of calcium carbonate and are products of limestone dissolution by acidic water containing CO2, leading to CaCO3 precipitation.
Step-by-step explanation:
The feature in a cave produced from a chemical reaction that drips from the ceiling is known as stalactites, while the features that are formed from the ground are called stalagmites. These cave formations are made up of calcium carbonate (CaCO3) and are a result of limestone being dissolved by water containing carbon dioxide, which then precipitates to form these structures.
When the dissolved CaCO3-rich water reaches the ceiling of a cave, it drips down and, upon losing carbon dioxide to the air, the water's pH increases, causing calcium carbonate crystals to form. The deposited limestone can take thousands of years to develop into the fantastical shapes that attract visitors to caves around the world.