If you're likely to get confused between the two terms, remember stalactite as the one which has a 'c' in its spelling (c stands for ceiling), and remember stalagmite as the one which has a 'g' in its spelling (g stands for ground). Hence stalactites descend from the ceiling and stalagmites rise from the ground.
Both stalactites and stalagmites are collectively referred to as dripstones and belong to a wide category of cave formations technically referred to as speleothems. A speleothem is a cave formation which results from moving water containing limestone (calcium carbonate) or other types of minerals. Hence these type of structures are found mostly in limestone or dolostone caves.
Stalactites and stalagmites vary in shape size and color. A lot of factors contribute to these variations, some of the important ones being the intensity of the mineral in water, rate and direction of the moving water, temperature of the cave, amount of annual rainfall, air currents, etc.
Refer below to a photograph of a limestone cave showing both stalactites and stalagmites, and a brief comparison between the two based on their formation.
Stalactites and Stalagmites: What's the difference?
➤ The first fundamental difference between the two is the place of formation. Both are formed in caves, however, stalactites extend from the ceiling whereas stalagmites rise from the ground.
➤ Stalactites are formed as a result of water dripping from the ceiling. This water carries a mineral Calcite essentially found in limestone caves as it flows, and leaves the mineral's deposits as it drips down the ceiling. Stalagmites, on the other hand are also deposits of the same mineral, but are formed out of the water hitting the floor.
➤ Stalactites lead to the formation of stalagmites, however the converse isn't possible.
➤ Stalactite comes from the Greek word stalasso, which means 'to drip'. Stalagmite originates from the Greek word stalagma which means 'dropping' or 'trickling'.
➤ Stalactites occur in different formations, for instance, Soda straw stalactites are very thin and long and are more cylindrical than conical. Some more stalactite types include, Helictites and Chandeliers. Stalagmites too have different types which are Broomstick stalagmites, Totem pole stalagmites, and Fried eggs stalagmites.
Interesting Facts about Mineral Deposits
Draperies are thin, wavy, fabric-like sheets of mineral which descend from the ceiling.
Cave formations can be composed of different materials; for instance, lava, minerals, mud, ice, and the like.
Cave pearls on the other hand, are small seed like structures caused due to water dripping from an extensive height. These are referred to pearls because they form almost perfect spheres.
Lava speleothems are formed by cooling of residual lava, and not by dissolution of minerals.
Calcium carbonate speleothems look translucent white, whereas those from other minerals could be brown due to the inclusion of mud particles.