A Stalactite is growth of precipitated calcite downwards from a cave roof below the joint through which its feed solution emerges. The corresponding floor formation is a Stalagmite.
water and something else
A stalagmite forms when water containing dissolved minerals drips from the ceiling of a cave. As the water drips down, the minerals are deposited on the floor, slowly building up over time to create a cone-shaped sedimentary deposit known as a stalagmite.