Short answer
A stalactite is a lasting mineral deposit that grows as dissolved minerals are left behind by water. An icicle is frozen water formed from drips in cold conditions. Both can hang downward, but they consist of different material and form by different processes. 1 2
They can look alike, but mineral deposition versus freezing determines what each is.
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At a glance
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| Question | Stalactite | Icicle |
|---|---|---|
| Material | Usually calcite or another mineral | Water ice |
| Growth process | Mineral precipitation from water | Freezing of dripping water |
| Temperature dependence | Can persist without freezing | Melts when warmed sufficiently |
The table summarizes the cited definitions and the article’s stated scope. 1 2
What each thing is
Stalactite. A mineral deposit hanging from a cave ceiling or other overhead surface, built by deposition from dripping water. 1
Icicle. A hanging spike of ice formed as dripping water freezes. 2
Key differences
The shape is a weak test because stalactites are often described as icicle-like. In limestone caves, mineral-rich water can release carbon dioxide and leave calcite behind. An icicle forms as liquid water freezes into solid ice. 1 2
How to tell them apart
Consider the setting and material. A persistent stone-like formation on a cave ceiling is a stalactite; a clear or whitish frozen spike under a cold roof edge is an icicle. Avoid touching cave formations; they can be fragile. 1 2
Where they overlap
Both depend on dripping water and gravity, and both may appear as tapering downward projections. A cave can contain actual seasonal ice formations as well as mineral speleothems. 1 2
Edge cases
Not every stalactite is calcite, and some mineral deposits form outside natural caves. Ice caves can have hanging ice that resembles mineral stalactites; classify by substance and growth mechanism, not cave location alone. 1 2
Why the distinction exists
The distinction separates a geological depositional feature from a temporary frozen-water feature, despite their shared silhouette. 1 2
Common misconceptions
A stalactite is not simply a cave icicle that never melted. It accumulates mineral matter through a different process. 1 2
Examples
A calcite formation hanging for centuries in Mammoth Cave is a stalactite. Frozen runoff hanging from a gutter in winter is an icicle. 1 2
Sources
Sources checked October 3, 2026.
- National Park Service — Stalactites, Stalagmites, and Cave Formations. Stalactites.
- National Snow and Ice Data Center — Icicle. Glossary definition.