Stalactites are secondary mineral formations that grow from the ceilings of limestone caves. They are a sub-class of speleothems, which are mineral deposits formed by the slow precipitation of dissolved minerals, such as calcite, from dripping water. Stalactites are characterized by their icicle-like shape, tapering from a broad base at the ceiling to a narrow tip as they grow downward. Their size can vary greatly, with some extending just a few centimeters, while others reach several meters in length.

Mineral Makeup

Stalactites are primarily composed of calcite, a calcium carbonate mineral. Other minerals, such as aragonite, gypsum, or even amorphous silica, can also form stalactites under specific conditions. The mineral composition of a stalactite is determined by the dissolved minerals present in the groundwater and the cave’s unique environment.


Stalactites form as a result of the slow precipitation of dissolved minerals from dripping water in limestone caves. When mineral-rich water drips from the cave ceiling, dissolved calcium carbonate reacts with carbon dioxide in the air and precipitates as calcite. Over time, these calcite deposits accumulate, creating the icicle-like shape of the stalactite.


Stalactites can be found in limestone caves worldwide, with some of the most impressive examples located in Carlsbad Caverns National Park (United States), Postojna Cave (Slovenia), and the Waitomo Glowworm Caves (New Zealand). The formation of stalactites requires specific environmental conditions, such as a constant water supply, dissolved minerals, and stable temperatures.


Stalactites are believed to possess metaphysical properties that promote spiritual growth, emotional healing, and connection to the Earth’s energy. They are thought to help individuals find inner strength and resilience in times of change or adversity. Stalactites are also associated with the passage of time and the patience required for personal transformation and growth.

ClassSedimentary (Chemical)
Mineral MakeupPrimarily calcite, with possible aragonite, gypsum, or amorphous silica 
LusterVitreous to pearly 
Hardness (Mohs)3 (calcite) – varies depending on mineral composition 
StreakWhite (calcite) – varies depending on mineral composition
ColorWhite, cream, or light brown – varies depending on mineral composition and impurities 
CleavagePerfect in three directions, rhombohedral (calcite) – varies depending on mineral composition
Specific Gravity2.71 (calcite) – varies depending on mineral composition