Cave popcorn, or cave coral, is a very common cave formation

Speleothem

A speleothem , commonly known as a cave formation, is a secondary mineral deposit formed in a cave. Speleothems are typically formed in limestone or dolostone solutional caves.-Origin and composition:...

. It actually comes in many sizes, shapes, and colors, but is most often found in small, knobby clusters resembling popcorn

Popcorn

Popcorn, or popping corn, is corn which expands from the kernel and puffs up when heated. Corn is able to pop because, like sorghum, quinoa and millet, its kernels have a hard moisture-sealed hull and a dense starchy interior. This allows pressure to build inside the kernel until an explosive...

. It is considered a subcategory of a more diverse type of speleothem called a coralloid.

Cave popcorn is composed of calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

and forms by several different mechanisms, including deposition by seeping water and underwater deposition on the walls and floors of pools. Sometimes, cave coral forms as knobs or branching stems that extend several inches from walls or floors.

External links

• The Virtual Cave's page on cave popcorn
• The Virtual Cave's page on coralloids