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Anthodites (
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
ἄνθος ''ánthos'', "flower", ''-ode'', adjectival combining form, ''-ite'' adjectival suffix) are
speleothem A speleothem (; ) is a geological formation by mineral deposits that accumulate over time in natural caves. Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. They can take a variety of forms, depending on ...
s (cave formations) composed of long needle-like crystals situated in clusters which radiate outward from a common base. The "needles" may be quill-like or feathery. Most anthodites are made of the mineral
aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including prec ...
(a variety of calcium carbonate, CaCO3), although some are composed of
gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...
(CaSO4·2H2O). The term ''anthodite'' is first cited in the scientific literature in 1965 by Japanese researcher N. Kashima, who described "flower-like dripstone" composed of "an alternation of calcite and aragonite".


Structure, composition and appearance

The individual crystals of anthodites develop in a form described as "acicular" (needle-like) and often branch out as they grow. They usually grow downward from a cave's ceiling. Aragonite crystals are contrasted with those made of calcite (another variety of calcium carbonate) in that the latter tend to be stubby or dog-tooth-like ("rhombohedral", rather than acicular). Anthodites often have a solid core of aragonite and may have
huntite Huntite is a carbonate mineral with the chemical formula Mg3Ca(CO3)4. Huntite crystallizes in the trigonal system and typically occurs as platy crystals and powdery masses. For most of recorded history its main use was as a white pigment. Today ...
or
hydromagnesite Hydromagnesite is a hydrated magnesium carbonate mineral with the formula Mg5(CO3)4(OH)2·4H2O. It generally occurs associated with the weathering products of magnesium containing minerals such as serpentine or brucite. It occurs as incrustations ...
deposited near the ends of the branches. Anthodite crystals vary in size from less than a millimeter to about a meter, but are commonly between 1 and 20 millimeters in length.


Occurrence

Anthodites may occur sporadically throughout some limestone caves, but may be spectacularly abundant in others, with clean white crystals growing all over the calcite or other rock surfaces. Examples of sites with abundant anthodite displays include
Carlsbad Caverns Carlsbad Caverns National Park is an American national park in the Guadalupe Mountains of southeastern New Mexico. The primary attraction of the park is the show cave Carlsbad Cavern. Visitors to the cave can hike in on their own via the natura ...
,
Craighead Caverns Craighead Caverns is an extensive cave system located in between Sweetwater and Madisonville, Tennessee. It is best known for containing the United States' largest and the world's second largest non- subglacial underground lake, The Lost Sea. ...
,
Skyline Caverns Skyline Caverns is a series of geologic caves and a tourist attraction located in Warren County, Virginia, south of Front Royal, Virginia, Front Royal. The caverns were discovered by Walter S. Amos, a retired geologist and mineralogist from Winch ...
in the United States and the
Grotte de Moulis Grotte may refer to: *Grotte, Sicily, a comune in the province of Agrigento, Italy * Grotte di Castro, a comune in the Province of Viterbo in the Italian region Latium *Robert Grotte, a New Zealand professional rugby league footballer * Nicolas ...
in France.


Types

Among the "quill-like" varieties of anthodite is sometimes included the "sea urchin-like" formation known as ''
flos ferri ''Flos'' is a genus of butterflies in the family Lycaenidae. The species of this genus are commonly known as plushblues and are found in the Indomalayan realm. Species *'' Flos diardi'' (Hewitson, 1862) - shining plushblue, bifid plushblue * ...
'', although othersShaw, T. (1992), ''History of Cave Science: The Exploration and Study of Limestone Caves to 1900'', 2nd ed.,
Sydney Speleological Society The Sydney Speleological Society Inc. (SSS) is a caving group based in Sydney, Australia. The Sydney Speleological Society was founded in 1954 and is one of the oldest caving groups in Australia. The Sydney Speleological Society has organised cavi ...
, Broadway, NSW, Australia.
have considered them a slender variety of
helictite A helictite is a speleothem (cave-formed mineral) found in a limestone cave that changes its axis from the vertical at one or more stages during its growth. Helictites have a curving or angular form that looks as if they were grown in zero grav ...
. Among the "feathery" varieties of anthodite is "
frostwork In geology, frostwork is a type of speleothem (cave formation) with acicular ("needle-like") growths almost always composed of aragonite (a polymorph of calcite) or calcite replaced aragonite. It is a variety of anthodite. Frostwork can also be ...
", a type of speleothem consisting of "bushes" of fine acicular aragonite crystals in radiating clusters. Their appearance is often compared to that of a cactus or thistle plant. In its composite
stalagmite A stalagmite (, ; from the Greek , from , "dropping, trickling") 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 ...
form, frostwork may possess spiny limbs like a miniature fir tree. The term was first used by cave guides at
Wind Cave Wind Cave National Park is an American national park located north of the town of Hot Springs in western South Dakota. Established on January 3, 1903 by President Theodore Roosevelt, it was the sixth national park in the U.S. and the first ca ...
in South Dakota, USA, during the 1890s to describe speleothems which looked like ice "frostwork".


Anthodite-like formations

*
Helictite A helictite is a speleothem (cave-formed mineral) found in a limestone cave that changes its axis from the vertical at one or more stages during its growth. Helictites have a curving or angular form that looks as if they were grown in zero grav ...
s are curved or angular twig-like lateral projections of calcium carbonate, which appear to defy gravity. Rather than radial clusters, helictites often occur in tangled masses. The "twigs" have a tiny central canal. *
Cave flower A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...
s (also known as "gypsum flowers" or "oulopholites") consist of gypsum or
epsomite Epsomite, Epsom salt, or magnesium sulfate heptahydrate, is a hydrous magnesium sulfate mineral with formula MgSO4·7H2O. Epsomite crystallizes in the orthorhombic system as rarely found acicular or fibrous crystals, the normal form is as massi ...
. In contrast to anthodites, the needles or "petals" of cave flowers grow from the attached end. * Cave cotton (also called "gypsum cotton") is very thin, flexible filaments of gypsum or epsomite projecting from a cave wall.


References

Speleothems