How do stalactites form?

Stalactites form primarily through the precipitation of minerals from dripping water. When water percolates through the ground and into a cave, it often contains dissolved calcium carbonate and other minerals. As the water drips from the cave ceiling, it loses carbon dioxide to the cave atmosphere, which causes the dissolved minerals to precipitate and crystallize, gradually building up the stalactite over time.

This process relies on the slow deposition of minerals as water repeatedly drips and evaporates, creating the characteristic formations we associate with caves. The formation of stalactites is linked to the specific conditions within the cave environment, including humidity and the chemical composition of the infiltrating water.

Other options don't accurately describe the process: evaporation of water may contribute to mineral deposition but does not itself lead directly to the formation of stalactites; bacteria growth does not produce stalactites but can affect cave ecosystems; and mineral deposits blown in by wind are not a mechanism for stalactite formation, as this process requires specific environmental conditions found within caves.