Stalactite in the context of Treak Cliff Cavern

43°12′16″N 23°29′28″E / 43.20444°N 23.49111°E / 43.20444; 23.49111

Ledenika (Bulgarian: Леденика, English: icy or glacial) is a cave in the Northwestern parts of the Balkan Mountains, 16 km away from the Bulgarian city of Vratsa. Its entrance is approximately 830 m above sea level. The cave features an abundance of galleries and impressive karst formations including stalactites and stalagmites. It was first discovered around the beginning of the 20th century and has been open to tourists since 1961. Ledenika Peak on Graham Land in Antarctica is named after the cave, in recognition of its cultural importance.

The Bacho Kiro cave (Bulgarian: пещера "Бачо Киро") is situated 5 km (3.1 mi) west of the town Dryanovo, Bulgaria, only 300 m (980 ft) away from the Dryanovo Monastery. It is embedded in the canyons of the Andaka and Dryanovo River. It was opened in 1890 and the first recreational visitors entered the cave in 1938, two years before it was renamed in honor of Bulgarian National Revival leader, teacher and revolutionary Bacho Kiro. The cave is a four-storey labyrinth of galleries and corridors with a total length of 3,600 m (11,800 ft), 700 m (2,300 ft) of which are maintained for public access and equipped with electrical lights since 1964. An underground river has over time carved out the many galleries that contain countless stalactone, stalactite, and stalagmite speleothem formations of great beauty. Galleries and caverns of a 1,200 m (3,900 ft) long section have been musingly named as a popular description of this fairy-tale underground world. The formations succession: Bacho Kiro's Throne, The Dwarfs, The Sleeping Princess, The Throne Hall, The Reception Hall, The Haidouti Meeting-Ground, The Fountain and the Sacrificial Altar.

A stalagmite (UK: /ˈstæləɡˌmaɪt/, US: /stəˈlæɡmaɪt/; from Greek σταλαγμίτης (stalagmítēs); from Ancient Greek σταλαγμίας (stalagmías) 'dropping, trickling' and -ίτης (-ítēs) 'one connected to, a member of')is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites are typically composed of calcium carbonate, but may consist of lava, mud, peat, pitch, sand, sinter, and amberat (crystallized urine of pack rats).

The corresponding formation hanging down from the ceiling of a cave is a stalactite.

A speleothem (/ˈspiːliəθɛm/; from Ancient Greek σπήλαιον (spḗlaion) 'cave' and θέμα (théma) 'deposit') is a geological formation made by mineral deposits that accumulate over time in natural caves. They can take a variety of forms, depending on their depositional history and environment. Common forms include stalagmites, stalactites, and flowstones.

Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. Their chemical composition, gradual growth, and preservation in caves make them useful paleoclimatic proxies.

Travertine (/ˈtrævərtiːn/ TRAV-ər-teen) is a form of fresh water limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and rusty varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. In the latter, it can form stalactites, stalagmites, and other speleothems.

Travertine is frequently used in Italy and elsewhere as a building material. Similar, but softer and extremely porous deposits formed from ambient-temperature water are known as tufa.

Fiorite is a hydrated silica mineraloid, a form of opal, found in cavities in volcanic tuff. It is a globular, botryoidal, or stalactic concretionary form of opal. The mineraloid has a pearly lustre and forms botryoidal masses. Named after Santa Fiora, Italy, fiorite is used as a gemstone.

A lava tube, more rarely called a pyroduct, is a 'roofed conduit through which molten lava travels away from its vent'. If lava in the tube drains out, it will leave an empty cave. Lava tubes are common in low-viscosity volcanic systems. Lava tubes are important as they are able to transport molten lava much further away from the eruptive vent than lava channels. A tube-forming lava flow can emplace on longer distance due to the presence of a solid crust protecting the molten lava from atmospheric cooling. Lava tubes are often considered when preparing hazard maps or managing an eruptive crisis.

The Qutb Minar, also spelled Qutub Minar and Qutab Minar, is a minaret and victory tower, built during the Delhi sultanate, and comprising the Qutb complex, a UNESCO World Heritage Site in Mehrauli, South Delhi, India. It was mostly built between 1199 and 1220, contains 399 steps, and is one of the most-frequented heritage spots in the city. After defeating Prithviraj Chauhan, the last Hindu ruler of Delhi before the Ghurid conquest of the region, Qutab-ud-din Aibak initiated the construction of the victory tower, but only managed to finish the first level. It was to mark the beginning of Islamic rule in the region. Successive dynasties of the Delhi Sultanate continued the construction, and, in 1368, Firuz Shah Tughlaq rebuilt the top parts and added a cupola.

It can be compared to the 62-metre all-brick Minaret of Jam in Afghanistan, of c. 1190, which was constructed a decade or so before the probable start of the Delhi tower. The surfaces of both are elaborately decorated with inscriptions and geometric patterns. The Qutb Minar has a shaft that is fluted with "superb stalactite bracketing under the balconies" at the top of each stage. In general, minarets were slow to be used in India and are often detached from the main mosque where they exist.

Goethite (/ˈɡɜːrtaɪt/, US also /ˈɡoʊθaɪt/) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the α-polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient times for its use as a pigment (brown ochre). Evidence has been found of its use in paint pigment samples taken from the caves of Lascaux in France. It was first described in 1806 based on samples found in the Hollertszug Mine in Herdorf, Germany. The mineral was named after the German polymath and poet Johann Wolfgang von Goethe (1749–1832).

A soda straw (or simply straw) is a speleothem in the form of a hollow mineral cylindrical tube. They are also known as tubular stalactites. Soda straws grow in places where water leaches slowly through cracks in rock, such as on the roofs of caves. Soda straws in caves rarely grow more than a few millimetres per year and may average one tenth of a millimetre per year. A soda straw can turn into a stalactite if the hole at the bottom is blocked, or if the water begins flowing on the outside surface of the hollow tube. Soda straws can also form outside the cave environment on exposed concrete surfaces as a type of calthemite, growing significantly faster than those formed on rock.

The Cradle of Humankind is a paleoanthropological site that is located about 50 km (31 mi) northwest of Johannesburg, South Africa, in the Gauteng province. Declared a World Heritage Site by UNESCO in 1999, the site is home to the largest known concentration of human ancestral remains anywhere in the world. The site currently occupies 47,000 hectares (120,000 acres) and contains a complex system of limestone caves. The registered name of the site in the list of World Heritage Sites is Fossil Hominid Sites of South Africa.

According to the South African Journal of Science, Bolt's Farm is the place where the earliest primates were discovered. Bolt's Farm was heavily mined for speleothem (calcium carbonate from stalagmites, stalactites, and flowstones) in the terminal nineteenth and early twentieth centuries.

A solutional cave, solution cave, or karst cave is usually formed in a soluble rock like limestone, of which calcium carbonate (CaCO₃) composes. Being the most common type of cave, it can also form in other rocks, including chalk, dolomite, marble, salt beds, and gypsum.