Speleothem

Speleothems ( /ˈspiːliːəθɛm/; Ancient Greek: 'cave deposit'), commonly known as cave formations, are secondary mineral deposits formed in a cave. Speleothems typically form in limestone or dolomite solutional caves. The term 'speleothem' as first introduced by Moore (1952), is derived from the Greek words spēlaion 'cave' + théma 'deposit'. The definition of 'speleothem' in most publications, specifically excludes secondary mineral deposits in mines, tunnels and on man-made structures. Hill and Forti more concisely defined 'secondary minerals' which create speleothems in caves as;A 'secondary' mineral is one which is derived by a physicochemical reaction from a primary mineral in bedrock or detritus, and/or deposited because of a unique set of conditions in a cave; i.e., the cave environment has influenced the mineral's deposition.Various formations in the Hall of the Mountain Kings, Ogof Craig a Ffynnon, South Wales, Great Britain.Stalactites and columns in Natural Bridge Caverns, Texas, U.S..More Formations in Natural Bridge Caverns, Texas, U.S..Cave curtain formation in the Marble Arch Caves, County Fermanagh, Northern Ireland.California Caverns, Calaveras County, California; one of many caverns located in the Sierra Foothills of California.Stalagnates (columns) in the cave Biserujka, Dobrinj, Island Krk, Croatia. Speleothems ( /ˈspiːliːəθɛm/; Ancient Greek: 'cave deposit'), commonly known as cave formations, are secondary mineral deposits formed in a cave. Speleothems typically form in limestone or dolomite solutional caves. The term 'speleothem' as first introduced by Moore (1952), is derived from the Greek words spēlaion 'cave' + théma 'deposit'. The definition of 'speleothem' in most publications, specifically excludes secondary mineral deposits in mines, tunnels and on man-made structures. Hill and Forti more concisely defined 'secondary minerals' which create speleothems in caves as; 319 variations of cave mineral deposits have been identified. The vast majority of speleothems are calcareous, composed of calcium carbonate in the form of calcite or aragonite, or calcium sulfate in the form of gypsum. Calcareous speleothems form via carbonate dissolution reactions. Rainwater in the soil zone reacts with soil CO2 to create weakly acidic water via the reaction: As the lower pH water travels through the calcium carbonate bedrock from the surface to the cave ceiling, it dissolves the bedrock via the reaction: When the solution reaches a cave, degassing due to lower cave pCO2 drives precipitation of CaCO3: Over time the accumulation of these precipitates form stalagmites, stalactites, and flowstones, which compose the major categories of speleothems. Calthemites which occur on concrete structures, are created by completely different chemistry to speleothems. Speleothems take various forms, depending on whether the water drips, seeps, condenses, flows, or ponds. Many speleothems are named for their resemblance to man-made or natural objects. Types of speleothems include: Speleothems made of sulfates, carbonates, mirabilite or opal occur in some lava tubes. Although sometimes similar in appearance to speleothems in caves formed by dissolution, lava stalactites are formed by the cooling of residual lava within the lava tube.