Infobox mineral name Aragonite category Carbonate mineral boxwidth boxbgcolor image Aragonite Salsigne France.jpg imagesize caption Aragonite from Salsignes Mine, Aude department, France Size 30x30x20 ... ref ref name Webmin http webmineral.com data Aragonite.shtml Webmineral data ref Aragonite is a carbonate ... and freshwater environments. Aragonite s crystal lattice differs from that of calcite, resulting in a different ... twinning results in pseudo hexagonal forms. Aragonite may be columnar or fibrous, occasionally in branching ... location for aragonite is Molina de Arag n Province of Guadalajara Guadalajara , Spain , 25 km from Aragon for which it was named in 1797. ref name Mindat An aragonite cave, the Ochtinsk Aragonite Cave , is situated in Slovakia . In the USA, aragonite in the form of stalactite s and cave flowers anthodite is known from Carlsbad Caverns and other caves. Massive deposits of oolitic aragonite sand are found on the seabed in the Bahamas . Aragonite forms naturally in almost all mollusk shells ... different from those of inorganic aragonite. In some mollusks, the entire shell is aragonite in others, aragonite forms only discrete parts of a bimineralic shell aragonite plus calcite . Aragonite ... s, respectively. The nacreous layer of the aragonite fossil shells of some extinct ammonite s forms an iridescent material called ammolite . Ammolite is primarily aragonite with impurities that make it iridescent and valuable as a gemstone . Aragonite is metastable and is thus commonly replaced by calcite in fossils. Aragonite older than the Carboniferous is essentially unknown. ref cite doi 10.1080 03115518508618971 ref Physical properties Aragonite is thermodynamics thermodynamically unstable ... even more readily than aragonite. Uses In aquaria , aragonite is considered essential for the replication ... level. Gallery gallery widths 200px heights 200px Image Aragonite 2 Enguidanos.jpg Aragonite crystals from Cuenca, Castile La Mancha, Spain File Aragonite 232887.jpg Cluster of twinned aragonite from ... more details
Image CalciteAragonite.jpg thumb right The alternation of calcite and aragonite seas through geologic time . An aragonite sea contains aragonite and high magnesium calcite as the primary inorganic carbonate precipitates. Therefore, the chemical conditions of the seawater must be notably high in magnesium content for an aragonite sea to form. This is in contrast to a calcite sea in which low magnesium calcite is the primary inorganic marine calcium carbonate precipitate. The Early Paleozoic and the Middle to Late Mesozoic oceans were predominantly calcite seas, whereas the Middle Paleozoic through the Early Mesozoic and the Cenozoic including today are characterized by aragonite seas. ref harvnb Wilkinson Owen Carroll 1985 ref ref harvnb Wilkinson Given 1986 ref ref harvnb Morse Mackenzie 1990 ref ref harvnb Lowenstein Timofeeff Brennan Hardie 2001 ref ref harvnb Palmer Wilson 2004 ref Aragonite seas form due to several factors, the most obvious of these is a high magnesium content. However, the sea level and the temperature of the surrounding system also determine whether an aragonite sea will form. ref harvnb Adabi 2004 ref Aragonite is the predominant mineral in warm, shallow marine environments. Calcite on the other hand, is the dominant mineral in cool marine water environments. This trend has been observed by looking at the chemistry of carbonates, dating them and analyzing the conditions under which they were formed. One study has examined the temporal and spatial distribution ... similar to today s seas which favor aragonite production. ref harvnb Westphall Munnecke 2003 ref Citations ... as evidence of large scale, early skeletal aragonite dissolution in a Silurian Sea journal Geology ..., A. year 2004 title A re evaluation of aragonite versus calcite seas journal Carbonates and Evaporites ... of biogenic aragonite in shallow Ordovician calcite seas journal Lethaia volume 37 pages 417 427 ... evidence for early aragonite dissolution in ancient calcite seas journal Nature volume 335 ... more details
Oolitic aragonite sand forms in tropical waters. Most of the topography of the Bahama Banks is composed of calcium carbonate Oolite oolitic aragonite sand material. The natural formation through Precipitation chemistry precipitation and sedimentation of aragonite sand in the Bahamas surpasses anyplace else in the world. Fact date June 2009 There are billions of tons of this type of sand material in reserve and millions of tons more created annually. Fact date June 2009 Commercial uses Commercial uses are similar to limestone and other high calcium carbonate materials. References http coralreefwatch.noaa.gov satellite oa description oaps intro aragonite ss.html An Introduction to Ocean Acidification See also List of types of limestone Category Sediments ocean stub ... more details
Image Ochtina Aragonite Cave 38.jpg thumb 240px White aragonite forms the cave s rare decoration Ochtinsk Aragonite Cave lang sk Ochtinsk aragonitov jasky a , lang hu Martonh zi aragonitbarlang Citation needed date August 2008 the Magyar Wikipedia article uses a different title is a unique aragonite cave situated in southern Slovakia , near Ro ava . Although only 300 m long, it is famous for its rare aragonite filling. ref name Mallows Mallows cite book last Lucinda Mallows first Lucy Mallows title Slovakia The Bradt Travel Guide year 2007 publisher Bradt Travel Guides isbn 1841621889 pages 6 url http books.google.cz books?id E xg8GbdZykC&pg PA6&dq ochtinsk C3 A1 aragonite cave&hl cs&sa X&ei 1i8wT7SeN8vqggfK oH3Dw&ved 0CDwQuwUwAg v onepage&q ochtinsk C3 A1 20aragonite 20cave&f false ref Description There are only three aragonite caves discovered in the world so far. In the so called Milky Way Hall, the main attraction of the cave, white branches and clusters of aragonite shine like stars in the Milky Way . The cave was discovered by Martin Cang r and Jiri Prosek in 1954 and opened to the public in 1972. Along with other caves of the Slovak Karst , it is included in the UNESCO World Heritage list as a component of Caves of Aggtelek Karst and Slovak Karst site. See also List of caves in Slovakia Gallery gallery Image Ochtina Aragonite Cave 28.jpg Aragonite inside the cave. gallery References Reflist External links Commons category Ochtina Aragonite Cave http www.sacr.sk article?id 14&category 9&lang en Short overview for tourists http www.ssj.sk jaskyne spristupnene ochtinska aragonitova Official site with pictures, map of the cave, and contact information World Heritage Sites in Slovakia coord 48 39 49.12 N 20 18 20.35 E dim 200 scale 2000 region SK type landmark source dewiki display title DEFAULTSORT Ochtinska Aragonite Cave Category Show caves in Slovakia Category World Heritage Sites in Slovakia Slovakia geo stub be be x old ... more details
3 sub and has a JCPDS number of 13 192. Vaterite, like aragonite, is a metastable phase of calcium ... or aragonite, vaterite has a higher solubility than either of these phases. Therefore, once vaterite is exposed to water , it converts to calcite at low temperature or aragonite at high temperature ... the vaterite and prevent its transformation into calcite or aragonite. Vaterite is usually colorless ... in some aragonite shelled mollusks e.g. gastropods . Subsequent shell deposition occurs as aragonite ... after aragonite. The crystal contains triplet of aragonite inside of it. On the its termination twin seams of aragonite triplet are well visible. Vaterite belongs to the hexagonal crystal system , whereas calcite is trigonal and aragonite is orthorhombic . See also Monohydrocalcite Monohydrocalcite ... more details
Image Jewel Cave 3.jpg thumb upright 1.75 alt frostwork Frostwork in Jewel Cave, South Dakota. Frostwork is a type of speleothem cave formation composed of acicular needle like growths almost always composed of aragonite a Polymorphism materials science polymorph of calcite or calcite replaced by aragonite ref Hill, C. and Forti, P. 1997 , Cave Minerals of the World , National Speleological Society , 2nd Edition. ref . It is a variety of anthodite . In some caves frostwork may grow on top of cave popcorn or boxwork . Formation The origin of frostwork is somewhat controversial. Formation of cave frostwork has been attributed to moist, circulating air which, containing dissolved calcium carbonate , drifted against rock surfaces and coated them with the delicate crystals. Frostwork has also been attributed to water seepage from cave passageways in which there are relatively high evaporation rates. Occurrence Notable frostwork deposits are found in a number of cave s in the Black Hills region of South Dakota , USA , most notable in Wind Cave National Park and Jewel Cave National Monument . Perhaps the most extensive displays known are found in Lechuguilla Cave , New Mexico. References references External links http www.nps.gov archive wica Speleothems.htm Wind Cave National Park Speleothems http www.goodearthgraphics.com virtcave aragonit aragonit.html The Virtual Cave s page on aragonite and frostwork Category Speleothems geology stub ... more details
orphan date January 2010 Coleolids are Cambrian Small shelly fossils with an aragonite skeleton. ref name Porter cite doi 10.1126 science.1137284 ref Their affinity is unknown but they were probably produced by an organism of the annelid grade of complexity. ref name BriggsCrowther cite book title Palaeobiology II By Derek E. G. Briggs, Peter R. Crowther ref rp 37 References reflist Category Cambrian animals Category Prehistoric life paleo stub ... more details
Image CalciteAragonite.jpg thumb right The alternation of calcite and aragonite seas through geologic time . A calcite sea is one in which low magnesium calcite is the primary inorganic marine calcium carbonate precipitate. An aragonite sea is the alternate seawater chemistry in which aragonite and high magnesium calcite are the primary inorganic carbonate precipitates. The Early Paleozoic and the Middle to Late Mesozoic oceans were predominantly calcite seas, whereas the Middle Paleozoic through the Early Mesozoic and the Cenozoic including today are characterized by aragonite seas Wilkinson et al., 1985 Wilkinson and Given, 1986 Morse and Mackenzie, 1990 Lowenstein et al., 2001 Palmer and Wilson, 2004 . Image CarmelHdgd.jpg thumb left Jurassic hardground with encrusting oysters and borings. The most significant geological and biological effects of calcite sea conditions include rapid and widespread ... , and the contemporaneous dissolution of aragonite shells in shallow warm seas Cherns and Wright ... and Jurassic , but virtually absent from the aragonite seas of the Permian Palmer, 1982 ... infaunal and or had thick periostraca Pojeta, 1971 , or had an inner shell of aragonite and an outer shell of calcite Harper et al., 1997 . This was apparently because aragonite dissolved quickly on the seafloor ... in the Mg Ca ratio favors the precipitation of calcite over aragonite. Increased seafloor ... et al., 2001 . gallery Image CalciteSeasTable.jpg Table showing the conditions for calcite and aragonite ... of the original aragonite shell and calcitic cementation of the mold. Image NautiloidInternalExternal.jpg ... aragonite shell and calcitic cementation. Image Paleosabella4CS.jpg The boring Palaeosabella ... Missing molluscs as evidence of large scale, early skeletal aragonite dissolution in a Silurian ... aragonite in shallow Ordovician calcite seas journal Lethaia volume 37 issue 4 pages 417 427 http ..., Hudson, J.D., Wilson, M.A. year 1988 title Palaeoecological evidence for early aragonite dissolution ... more details
Aragonite Cave is just 300 m long with a tourist circuit not longer than 230 m, it is famous for its rare aragonite filling since there are only three aragonite caves discovered in the world so far. In the so called Milky Way Hall, the main attraction of the cave, white branches and clusters of aragonite ... Image Okt 15.jpg Baradla Cave Image Ochtina Aragonite Cave 54.jpg Ochtina Aragonite Cave Image Ochtina Aragonite Cave 29.jpg Ochtina Aragonite Cave Image Ochtina Aragonite Cave 12.jpg Ochtina Aragonite Cave Image Ochtina Aragonite Cave 38.jpg Detail of the aragonite decoration Image Ochtina Aragonite Cave 22.jpg Detail of the aragonite decoration Image Jaskinia Gombasecka 3.jpg Gombasek Cave Image ... more details
and ancient rocks, indicating the removal of a soluble polymorph usually aragonite . Variation ... of growth by accretion like a snowball from the polymineralic sediment of fine aragonite, high magnesium calcite HMC and low magnesium calcite LMC , must explain how only aragonite needles ... more details
Unreferenced date November 2006 Taxobox name Linguliformea regnum Animal ia phylum Brachiopod a subphylum Linguliformea subdivision ranks Classes subdivision Lingulata br Paterinata Linguliformea is a subphylum of inarticulate brachiopod s. These were the earliest of brachiopods, ranging from the Cambrian into the Holocene . They rapidly diversified during the Cambrian into the Ordovician , but most families went extinct by the end of the Devonian . The articulation in these brachiopods is lacking. These brachiopods have adductor and oblique muscles, but no diductor muscles. The anus is located at the side of the body. The pedicle is a hollow extension of the ventral body wall. Posterior body wall separates dorsal and ventral mantles. The shells are usually made up of apatite calcium phosphate , however rare cases have calcite or aragonite shells. Category Brachiopods Brachiopod stub ... more details
Hermatypic corals , or stony corals , are reef building coral s, while corals that do not deposit aragonite structures and contribute to coral reef development are referred to as ahermatypic non reef building species. ref cite journal author Schuhmacher H, Zibrowius H title What is hermatypic? journal Coral Reefs volume 4 issue pages 1 9 year 2006 doi 10.1007 BF00302198 ref References reflist invertebrate stub corals Category Anthozoa Category Coral reefs la Curalium hermatypicum zh ... more details
Speciesbox genus Heloplax species papilla authority Cherns, 1998 Heloplax is a worm like mollusc . Its soft parts are preserved in three dimensions in the Silurian Herefordshire lagerstatte its disarticulated valves are known from other Silurian deposits. ref name Sutton2004 cite doi 10.1111 j.0031 0239.2004.00374.x ref It is very bizarre by modern standards it bears serially repeated units, and has spines. It probably falls somewhere between the aplacophorans and polyplacophora its valves were composed of aragonite ref name Sutton2004 References reflist Category Chitons Chiton stub ... more details
Automatic taxobox taxon Cambroclavida authority Conway Morris and Chen, 1991 fossil range Fossil range Lower Cambrian Middle Cambrian Cambroclaves are a group of enigmatic, phosphatized, hollow spine shaped sclerites, known from their geographically widespread Early to Middle Cambrian fossils. ref name Wotte2009 cite doi 10.1666 08 039R.1 ref They were probably originally aragonitic. ref name Porter2010 cite doi 10.1111 j.1472 4669.2010.00246.x ref They are lobate with long spines protruding centrally these spines are in some cases e.g. Zhijinites pillar like, constituted of a bundle rods originally aragonite? with an Ionic like appearance. Ref Cite palaeontology volume 40 first page 167 last page 189 ref reflist Category Scientific classification Category Incertae sedis ... more details
Image StenotremaFlorida1.jpg thumb right 200px The shell of Stenotrema florida , a land snail. The periostracum is an organic layer of protein which, in this species, is developed into minute hairs, giving the snail a velvety look and feel Conchiolin sometimes referred to as conchin and perlucin are complex protein s which are secreted by a mollusc s outer epithelium the mantle mollusc mantle . These proteins are part of a matrix of organic macromolecules, mainly proteins and polysaccharides, that assembled together form the microenvironment where crystals nucleate and grow. This organic matrix also holds and binds to the crystals of aragonite which give such shells their stiffness. The ion s necessary to form calcium carbonate are also secreted by the mantle, but it is the tailored environment created by the organic matrix which causes aragonite rather than calcite crystals to nucleate, in much the same way that collagen nucleates hydroxyapatite crystals. Conchiolin serves as a relatively flexible, crack deflecting extracellular matrix matrix for the mineral aggregate composite aggregate particles its strength and the strong bonding of perlucin can in some cases such as in the formation of nacre give the finished material an impressive level of toughness . As well as providing a matrix into which the hard calcium carbonate part of the shell is precipitated, many species of mollusks such as the land snail shown above also have an outer shell layer called the periostracum which is composed of the protein conchiolin. See also Mollusc shell Periostracum Corneous Chitin Tectin secretion Tectin Sporopollenin External links http www.jcb.org cgi content abstract 9 2 395 Structure of the conchiolin cases of the prisms in Mytilus edulis , Charles Gr goire, 1960 Category Proteins Category Molluscs protein stub de Conchiolin es Conquiolina fr Conchyoline it Conchiolina nl Conchioline pl Konchiolina pt Conchiolina ru ... more details
File Cave popcorn trays.jpg thumb right Cave popcorn trays Cave popcorn , or coralloids, are small nodes of calcite , aragonite or gypsum that form on surfaces in cave s, especially limestone caves. ref name PALMER cite book last Palmer first Arthur N. title Cave Geology year 2007 publisher CAVE BOOKS location Dayton, OH isbn 978 0 939748 66 2 page 288 ref ref name HILL cite book last1 Hill first1 Carol first2 Paolo last2 Forti title Cave Minerals of the World Second Edition ed. year 1997 publisher National Speleological Society location Huntsville, AL isbn 1 879961 07 5 pages 59 61 ref They are a common type of speleothem . ref name PALMER ref name HILL Appearance The individual nodules of cave popcorn range in size from 5 20 mm and may be decorated by other speleothems especially aragonite needles or frostwork . ref name PALMER ref name HILL The nodules tend to grow in clusters on bedrock or the sides of other speleothems. ref name PALMER These clusters may terminate suddenly in either an upward or downward direction forming a stratographic layer. ref name PALMER When they terminate in a downward direction, they may appear as flat bottomed formations otherwise known as trays. ref name PALMER The color of cave popcorn is usually white but various other colors are possible depending on the composition. ref name HILL Formation Cave popcorn can form by precipitation by the loss of CO sub 2 sub . ref name PALMER When formed in this way the nodules have the characteristics of small balls of flowstone . ref name PALMER It can also form by evaporation in which case it is chalky and white like edible popcorn . ref name PALMER In the right conditions, evaporative cave popcorn may grow on the windward side of the surface to which it is attached or appear on the edges of projecting surfaces. ref name PALMER References reflist External links http www.goodearthgraphics.com virtcave popcorn popcorn.html The Virtual Cave s page on cave popcorn http www.goodearthgraphics.com virtc ... more details
Calcareous sinter is a freshwater calcium carbonate deposit, also known as calc sinter . Deposits are characterised by low porosity and well developed lamination. Calcareous sinter should not be confused with siliceous sinter , which the term sinter more frequently refers to. It has been suggested that the term sinter should be restricted to siliceous spring deposits and be dropped for calcareous deposits entirely. Features Calcareous sinter is characterised by laminations of prismatic crystals growing perpendicular to the substrate laminations are separated by thin layers of microcrystalline carbonate. ref Fl gel, E. 2004. Microfacies of Carbonate Rocks . Germany Spring Verlag. ISBN 3 540 22016 X ref Macrophyte s are absent, consequently porosity is very low. Exclusion of species is due either to high temperature travertine , high pH ion content tufa or absence of light speleothem s . Pedley 1990 ref Pedley, H.M. 1990. Classification and environmental models of cool freshwater tufas. Sedimentary Geology 68 , pp. 143 154. ref suggests the term be abandoned in favour of tufa for ambient temperature deposits and presumably travertine for geothermally heated deposits . This avoids any potential confusion with siliceous sinter and prevents deposits formed in different environmental conditions hot spring deposits, cold spring deposits and speleothems are all lumped together under the term sinter from being amalgamated into one group. Geochemistry Deposits are formed from either calcite or aragonite . Precipitation is brought about by degassing of CO sub 2 sub , which decreases the solubility of calcite aragonite. See tufa Geochemistry tufa geochemistry Notable Deposits gallery Image Kalksinter.JPG Pure calc sinter, typical for aqueduct s and all kinds of water facilities. Image Eifelwasserleitung05.jpg Roman aqueduct in Germania Inferior . Eifel Aqueduct , clogged by fine sinter. Image Travertine mound Bridgeport CA.jpg Deposits of several thousand years of calc sinter t ... more details
File Flor e bolha.JPG thumb right 220px An uncommon speleothem formed by a flower of aragonite enclosed by a bubble of calcite located inside Gruta da Torrinha. Gruta da Torrinha BA 037 is a cave located in the village of Torrinha , 15 km from the town of Iraquara and 1 km of the highway BA 122, inside the area of the Chapada Diamantina National Park , in the State of Bahia , Brazil . It is considered the most beautiful cave within the area of the state, having the second largest flower of aragonite in the world. ref name Eco Tur cite web last Eco Tur title Torrinha url http www.eco.tur.br ecoguias diamantina ecopontos cavernas torrinha.htm accessdate 30 December 2011 ref Geology The first part of the topographic mapping 600m was made in 1992 by Meanders Speleological Group, from France . The cave was discovered in 1850 and has three routes open to tourist visits with one of them that can be covered within 3 hours. Today there are only 8.300 meters mapped. ref cite web last HjoBrasil title Fotos e dados da Caverna Torrinha url http www.hjobrasil.com ordem.asp?secao 1&categoria 723&subcategoria 1469&id 5191 publisher HjoBasil accessdate 30 December 2011 ref The tourism industry has become the main source of income for the administrator of the local people and neighbors. It is the most complete cave for presenting rare speleothem cave formations s as helictite s, needles of gypsum that look like glass and subterranean lakes. See also List of caves in Brazil References Reflist External links http www4.icmbio.gov.br cecav index.php?id menu 228 Base de Dados do Ministerio do Meio ambiente Governo Federal ICMBIO Official Website Caving stub coord 12 34 59 S 41 59 38 W region BR type landmark source dewiki display title Category Caves of Brazil Category Limestone caves Category Wild caves ... more details
italic title Unreferenced date March 2007 Taxobox name Acanthoplites status fossil fossil range regnum Animal ia phylum Mollusc a classis Cephalopod a subclassis Ammonoidea genus Acanthoplites genus authority subdivision ranks subdivision Acanthoplites is an extinct genus of cephalopod belonging to the Ammonite subclass. Like many other Ammonites, Acanthoplites was a marine nektonic carnivore. Fossil Record The most commonly preserved remains of Acanthoplites are the animals shells, which were composed of Aragonite . This animal first appears in rocks dating to the late Aptian portion of the Cretaceous Period. This means that Acanthoplites fossils are 112 125 million years old. No fossils of Acanthoplites have been found post dating the Aptian. Remains from this genus have been found on multiple continents in the nations of Mexico , Argentina , Morocco and South Africa Species A. aegis A. barryana A. crassicostatus A. gardneri A. gragasensis A. perrini A. spathi A. seunesi A. uhligi Category Ammonitida eu Acanthoplites pl Acanthoplites ... more details
Image California Murphys Mercer cave1.jpg thumb 100px Image California Murphys Mercer cave2.jpg thumb 100px Mercer Caverns are located outside of Murphys, California Murphys in Calaveras County California . They are named after the gold prospector Walter J. Mercer who discovered the cave s around 1885 and filed a claim. They were later renamed as caverns . The caverns have a large number of speleothem s, stalactite s, and stalagmite s. Under the limestone calcite are a range of aragonite minerals that are pure CaCO3 . ref cite web url http www.showcaves.com english usa showcaves Mercer.html title Mercer Caverns publisher accessdate 2007 03 28 ref See also Stalagmite Stalactite Notes references External links http www.mercercaverns.com Mercer Caverns official site http www.viamagazine.com top stories articles caves98.asp Exploring the Caves of Calaveras coord missing Calaveras County, California Category Landforms of Calaveras County, California Category Limestone caves Category Show caves in the United States Category Caves of California Category Visitor attractions in Calaveras County, California US geology stub ... more details
orphan date December 2007 Neomorphism is a recrystallization geology recrystallization process in sedimentary rock s that changes the size either larger or smaller and form it can include the overgrowth of Polymorphism materials science polymorphous minerals of crystals in the rock. The chemical composition of the rock remains the same. Neomorphism thus destroys the original crystals and builds new crystals that grow over the older ones. In limestone carbonate rocks neomorphism is an important step in the diagenesis of such rocks, in which the micrite micritic matrix geology matrix is exchanged for microspar s bigger, loaf shaped crystals . The process also reduces the amount of under surface conditions instable aragonite and magnesium rich calcite in the rock by replacing them with normal calcite. The name neomorphism was minted by Folk in 1965. ref Folk, R.L. 1965 Some aspects of recrystallization in ancient limestones , Society of Economic Paleontologists and Mineralogists, spec. pub. 13 , p. 14 48. ref References references Category Sedimentology nl Neomorfose ... more details
image Pb29 cut2.jpg frame Ceratoporella nicholsoni , cut specimen from Pedro Bank , Caribbean Sea , about 15 cm wide. Brown sponge tissue covers white massive aragonite skeleton . Sclerosponges are sea sponge sponge s with a soft body that covers a hard, often massive skeleton made of calcium carbonate , either aragonite or calcite . Because of their long life span 500 1,000 years it is thought that analysis of the aragonite skeleton s of these sponges could extend data regarding ocean temperature , salinity , and other variables farther into the past than has been previously possible. Their dense skeletons are deposited in an organized chronological manner, in concentric layers or bands. The layered skeletons look similar to reef coral s. Therefore sclerosponges are also called coralline sponges . Sclerosponges were first proposed as a class of sponges, Sclerospongiae , in 1970 by Hartman and Goreau. ref cite journal author W. D. Hartman and T. F. Goreau year 1970 title Jamaican coralline sponges Their morphology biology morphology , ecology and fossil relatives journal Symp. Zool. Soc. Lond. volume 25 pages 205 243 Cited by http mgg.rsmas.miami.edu groups sil work1.htm . ref However, it was later found by Vacelet that sclerosponges occur in different classes of sea sponge Porifera . ref cite journal author J. Vacelet year 1985 title Coralline sponges and the evolution of the Porifera journal System. Assoc. Spec. volume 28 pages 1 13 ref That means that sclerosponges are not a closely related Taxonomy taxonomic group of sponges. Like bat s and bird s that independently developed the ability to fly, different sponges developed the ability to build a calcareous skeleton independently and during different times in Geologic History of Earth Earth history . Fossil sclerosponges are already known from the Cambrian Period Cambrian period. ref cite journal author J. Reitner year 1992 title Coralline Spongien. Der Versuch einer phylogenetisch taxonomischen Analyse journal B ... more details
Image OoidSurface01.jpg thumb right 250px Ooids on the surface of a limestone Carmel Formation Middle Jurassic of southern Utah, USA. Largest is 1.0 mm in diameter. Allochem is a term introduced by Folk ref name Folk1959a Folk, R.L. 1959 Practical petrographic classification of limestones. American Association of Petroleum Geologists Bulletin. 43, pp. 1 38. ref to describe the recognisable grains in carbonate rocks . Any fragment from around mm upwards in size may be considered an allochem. Examples would include ooids , peloids , oncolite s, Pellets petrology pellets , fossil or pre existing carbonate fragments. Fragments are still termed allochems if they have undergone chemical transformations for example if an aragonite shell were to dissolve and be later replaced by calcite , the replacement would still be deemed an allochem. ref name ScholleOther2003a Scholle, P.A., and D.S. Ulmer Scholle 2003 A Color Guide to the Petrography of Carbonate Rocks Grains, textures, porosity, diagenesis. American Association of Petroleum Geologists Memoir no. 77. Tulsa, Oklahoma, American Association of Petroleum Geologists. 474 pp. ISBN 0891813586 ref The allochems are typically embedded in a Matrix geology matrix of micrite lime mud or sparry calcite. References reflist Category Sedimentology Category Sedimentary rocks Category Limestone geology stub ca Al loqu mic ... more details
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