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Topic: Vaterite

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Aragonite

Calcite

Pyrolusite

Calcium carbonate

Manganese(IV) oxide

Haematite

Calcium hydroxide

Manganese

Slaked lime

Magnesium oxide

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	Vaterite - Definition, explanation
		Unlike the other calcium carbonate polymorphs, calcite and aragonite, vaterite is thought to be a metastable phase and has higher solubility than the other forms of calcium carbonate.
		Therefore, once vaterite is exposed to water, it converts to calcite (at low temperature) or aragonite (at high temperature: ~60°C).
		The color of vaterite is usually white, its shape is spherical, and its diameter is small, ranging from 0.05 to 5 μm.
	www.calsky.com /lexikon/en/txt/v/va/vaterite.php (193 words)

	Reference.com/Encyclopedia/Vaterite
		Unlike the other calcium carbonate polymorphs, calcite and aragonite, vaterite is thought to be a metastable phase and has higher solubility than the other forms of calcium carbonate.
		Therefore, once vaterite is exposed to water, it converts to calcite (at low temperature) or aragonite (at high temperature: ~60°C).
		The color of vaterite is usually white, its shape is spherical, and its diameter is small, ranging from 0.05 to 5 μm.
	www.reference.com /browse/wiki/Vaterite (217 words)

	Vaterite at AllExperts
		Unlike the other calcium carbonate polymorphs, calcite and aragonite, vaterite is thought to be a metastable phase and has higher solubility than the other forms of calcium carbonate.
		Therefore, once vaterite is exposed to water, it converts to calcite (at low temperature) or aragonite (at high temperature: ~60Â°C).
		The color of vaterite is usually white, its shape is spherical, and its diameter is small, ranging from 0.05 to 5 μm.
	en.allexperts.com /e/v/va/vaterite.htm (258 words)

	Controlled crystallization of CaCO3 under stearic acid monolayers
		The vaterite nuclei are aligned with their (0001) face parallel to the plane of the organic substrate and develop initially in the form of disk-shaped single crystals.
		The degree of compression of the monolayer dictates the homogeneity of vaterite nucleation.
		In particular, partially compressed films are optimal for controlled crystallization, suggesting that the mobility of organic surfaces may be of general importance.
	www.nature.com /doifinder/10.1038/334692a0 (245 words)

	Method for manufacturing monodisperse vaterite type calcium carbonate - Patent 5494651
		Although it is possible to obtain vaterite type calcium carbonate at a high yield, arbitrary control of the particle size and shape thereof is infeasible, a further defect being that stable manufacture of monodisperse spherical, ellipsoidal or plate-like vaterite type calcium carbonate is also infeasible.
		In case spherical or ellipsoidal vaterite type calcium carbonate is intentionally manufactured by the method according to the second invention, the time elapsed from the start of carbonation reaction to where the conductivity in the carbonation reaction reaches the point D on the curve of conductivity variation in FIG.
		The vaterite type calcium carbonate obtained in Comparative Example 3 was found contaminated by many calcium carbonate particles of calcite type and aragonite type by X-ray diffraction measurement, and also confirmed to be broad in particle size distribution and inferior in quality by the experimental data in Table 4.
	www.freepatentsonline.com /5494651.html (9799 words)

	[No title]
		Vaterite and portlandite in the debris of oil-field drilling
		Vaterite and portlandite are not common in sediments, but we find these two minerals by X-ray analysis from the samples of marine carbonate rock.
		In our studies, the vaterite is a crystalline in the debris samples and not in the form of a colloid material.
	aapg.confex.com /aapg/no2000/techprogram/paper_3053.htm (284 words)

	Vaterite
		Although vaterite is the least stable anhydrous calcium carbonate polymorph, it is formed as a metastable...
		Vaterite (CaCO3) is a polymorph of aragonite and calcite.
		Vaterite, a CaCO[sub 3] polymorph, is a very rare mineral that is thought to be...
	www.toprocks.net /MineralList/97/Vaterite.asp (452 words)

	ABSTRACT: Naturally precipitating vaterite (mu-CaCO3) spheres: Unusual carbonates formed in an extreme environment. (Site not responding. Last check: )
		Vaterite, a rare hexagonal CaCO3 Polymorph, was identified in precipitates forming at a supraglacial sulfur spring, in Borup Fiord Pass, northern Ellesmere Island, Canadian High Arctic.
		Vaterite occurs in a precipitate mound along with calcite, gypsum, and native sulfur.
		Vaterite found at the site is characterized by 2- to 10-mum rounded to spherical shaped particles (comprising smaller 0.5- to 2-mum spheres) as both individuals and in chainlike structures.
	cgrg.geog.uvic.ca /abstracts/GrasbyNaturallyVaterite.html (197 words)

	Vateritic Otoliths - JPW Marine Research
		The aragonite matrix of the saggita was replaced either partially or completely by vaterite - another structural form of calcium carbonate usually only found in the astericii.
		This 10 year old white seabass began depositing vaterite instead of aragonite on one side at age 3 and was captured at age 10.
		It has been suggested that I map the different matrix areas; perform chemical analysis of whole otoliths, vaterite sections, or transition areas; determine at what age (and therefore approximate date) the transition occured; or simply run statistical analyses to determine any pattern in catch month, year, site, etc.
	www.jpwmarineresearch.com /vaterite.html (333 words)

	Conservation of Ornamental Stone by Myxococcus xanthus-Induced Carbonate Biomineralization -- Rodriguez-Navarro et al. ...
		Representative MIP plots showing both the cumulative intrusion curves (i.e., porosity) and pore size distribution curves [i.e., log of differential intrusion, or log(dv/dr), versus r, where v is the intruded volume and r is the pore radius] for fresh (solid line) and biomineralized (dotted line) stone samples.
		Microbial biscuits of vaterite in lake Issyk-Kul (Republic of Kyrgyzstan).
		The transformation of vaterite to calcite: effect of the conditions of the solutions in contact with the mineral phase.
	aem.asm.org /cgi/content/full/69/4/2182 (6504 words)

	Science/AAAS \| Editors' Choice : 09 May 2003; 300 (5621) (Site not responding. Last check: )
		Inorganic vaterite is rarely found on Earth and has never been conclusively found to precipitate from natural waters.
		Vaterite precipitation is favored because the water is extremely cold (1° to 2°C) and highly alkaline (pH 7.3 to 9.5).
		Understanding how vaterite forms in this extreme biogenic environment can help to explain carbonate precipitation under different conditions and provides clues about terrestrial extremophiles and their biomarkers, and perhaps useful analogs for other planetary environs.
	www.sciencemag.org /content/vol300/issue5621/twil.dtl (1319 words)

	Aragonite Mineral,Aragonite Information,Aragonite Uses,Aragonite Mineral Properties
		A very rare mineral called vaterite is also a polymorph of aragonite and calcite; making them all trimorphs.
		Vaterite has an hexagonal symmetry (6/m 2/m 2/m).
		Carbonate minerals with this same structure as aragonite belong to the Aragonite Group of minerals.
	www.mineralszone.com /minerals/aragonite.html (851 words)

	Hent.no - Norsk Pay Per Click Søkemotor: Vaterite (10) (Site not responding. Last check: )
		Aragonite and vaterite are polymorphs (latin for "many shapes") with calcite, meaning they all have the same chemistry, but different...
		It revealed that the main phases of CaCO 3 produced, are Calcite and Vaterite, and that their abundance is strongly dependent on the concentration of the organic additive.
		Spherical particles of vaterite Vaterite is a rare crystal form of calcium carbonate that is observed in the sulfur springs at Borup Fiord Pass, Ellesmere Island, Canada.
	www.hent.no /hent/search.php?Terms=Vaterite (294 words)

	e-Prints Soton - Stimulation of human bone marrow stromal cells using growth factor encapsulated calcium carbonate ... (Site not responding. Last check: )
		In this work, 5–30 µm-sized calcium carbonate (vaterite) spheroids with elaborate sponge-like macroporous architectures were prepared by passive evaporation of water-in-oil microemulsions, and investigated as potential vehicles for the delivery of skeletal growth factors to human bone marrow stromal cells maintained in culture.
		Use of vaterite microspheres to adsorb and deliver active growth factors such as pleiotrophin and an admixture of bone morphogenetic proteins derived from an osteosarcoma (SaOS retentate) was demonstrated using human bone marrow stromal cells.
		Ex vivo chorioallantoic membrane culture of pelleted vaterite spheres and human bone marrow cells placed into a chick femur defect resulted in the secretion of an organised collagen matrix.
	eprints.soton.ac.uk /25556 (408 words)

	Linda C. Kah (Site not responding. Last check: )
		Vaterite is a highly unstable polymorph of CaCO3 that precipitates as homogeneously nucleated sub-spherical crystals under supersaturated laboratory conditions and converts rapidly to calcite.
		If this is the case, determining environmental parameters (pH, temperature, carbonate saturation, presence of dissolved organics, etc.) that control the precipitation of spheroidal vaterite morphologies may provide an invaluable constraint on the chemistry and evolution of marine waters in the Precambrian.
		To this end, Adam is currently developing laboratory protocols for a series of vaterite precipitation experiments aimed at precipitating spheroidal carbonate crystal morphologies and determining the range of conditions under which these morphologies are reproducible.
	geoweb.gg.utk.edu /faculty/kah/students.html (1412 words)

	Blue Calcite
		Aragonite and vaterite are polymorphs with calcite, meaning they all have the same chemistry, but different crystal structures and symmetries.
		Aragonite is a common mineral, Vaterite on the other hand is extremely scarce and rarely seen.
		Calcite is polymorphous, (having the same chemical formula but different crystal structure) with the minerals aragonite and vaterite as well as with several other forms that apparently exist only under extreme experimental conditions.
	www.seabgems.com /blue_calcite.htm (854 words)

	Europa on Earth: The Sulfur Springs of Borup Fiord Pass, Ellesmere Island - Explore the Cosmos \| The Planetary Society
		Vaterite is a rare crystal form of calcium carbonate that is observed in the sulfur springs at Borup Fiord Pass, Ellesmere Island, Canada.
		Vaterite is one of many crystalline forms of calcium carbonate.
		This is only the second location on Earth where vaterite has been found to occur naturally.
	www.planetary.org /explore/topics/planetary_analogs/borup_fiord.html (1695 words)

	Iran Calcite,calcite mineral,calcite (Site not responding. Last check: )
		Aragonite and vaterite are polymorphs (latin for "many shapes") with calcite, meaning they all have the same chemistry, but different crystal structures and symmetries.
		Aragonite is a common mineral, but is vastly out distanced by calcite which is the more stable mineral at most temperatures and pressures and in most environments.
		Vaterite on the other hand is extremely scarce and rarely seen.
	www.redironoxide.com /calcite.php (1979 words)

	Descaling of water
		It is formed primarily because the solubility of calcium carbonate decreases with increasing temperature.
		Limescale is only a problem if calcium carbonate deposits rhombohedral calcite crystals, which may form directly or subsequent to metastable hexagonal and fibrous vaterite crystal formation.
		) the magnetic field produces mainly a mixture of aragonite (44%) and vaterite (42%) whereas without it well-crystallized calcite (34%) is formed with little aragonite (14%) [252].
	www.lsbu.ac.uk /water/descal.html (835 words)

	Overbased vaterite containing salt composition invention
		An overbased vaterite containing salt composition, comprising: a disperse medium, and a calcium salt and calcium carbonate dispersed in the disperse medium, at least about 50% by weight of the calcium carbonate being in the form of vaterite, the composition being substantially haze free.
		The process of claim 12 wherein the weight ratio of lower alcohol to midlevel alcohol is in the range from about 7:1 to about 1:2.
		A process for making an overbased vaterite containing salt composition, comprising: (i) mixing an overbased amorphous calcium carbonate containing salt composition with water and an alcoholic mixture comprising methanol, isobutyl alcohol and amyl alcohol; and (ii) contacting the resulting mixture with CO.sub.2 at a temperature in the range from about 45.degree.
	www.freshpatents.com /Overbased-vaterite-containing-salt-composition-dt20060817ptan20060183650.php?type=claims (837 words)

	LABORATORY PRECIPITATION AND GEOCHEMICAL INVESTIGATION OF UNSTABLE CACO3 POLYMORPHS: IMPLICATIONS FOR THE ORIGIN OF ... (Site not responding. Last check: )
		The volumetrically significant and global occurrence of MT calcite in shallow marine strata suggests linkages between carbonate fabric development and the broad-scale geochemical evolution Earth's early oceans.
		Laboratory precipitation of vaterite typically occurs at carbonate saturations far greater than is observed in modern marine systems.
		of a synthetic, pH-buffered seawater solution during laboratory precipitation of vaterite, we are attempting to constrain the conditions under which quantities of spheroidal vaterite, sufficient to fill MT voids, most readily form.
	gsa.confex.com /gsa/2006AM/finalprogram/abstract_116053.htm (412 words)

	Imaging On-Line Store (Site not responding. Last check: )
		As a substitute of expensive silica, calcium carbonate having a crystal form of vaterite was examined in terms of the preparation method for high purity and surface wetting behavior of its coated paper.
		Pure vaterite synthesis was successfully achieved by the modified interfacial reaction method, i.e., at a temperature of 25ºC of all the reacting liquids and high shear rate during mixture.
		Spherical vaterite aggregates developed so is around 1 µm diameter and consists of primary particle less than 100 nm diameter.
	www.imaging.org /store/epub.cfm?abstrid=33385 (250 words)

	Stabilization of the Vaterite Structure in the Presence Of Copper(II): Thermodynamic and Spectroscopic Studies (Site not responding. Last check: )
		The crystalline transformation of vaterite in the presence of copper(II) [Cu(II)] has been investigated in ultrapure water and at room temperature using several techniques; scanning electron microscopy (SEM), infrared (IR) and micro-Raman spectroscopy.
		To prove this suggestion, experiments on solubilities of Cu -vaterite solids were performed and interpreted in terms of thermodynamic equilibrium and stoichiometric saturation concepts.
		Thermodynamic and spectroscopic data demonstrate that the apparent stabilization of vaterite in the presence of Cu(II) is strongly dependent on the existence of water molecules in the lattice of the solid solution Cu
	pubs.acs.org /cgi-bin/abstract.cgi/cmatex/1999/11/i01/abs/cm9803399.html (285 words)

	Precipitation of Vaterite (CaCO3) During Oil Field Drilling (Site not responding. Last check: )
		According to the literature, vaterite precipitated from carbonate solution recrystallizes spontaneously to calcite or aragonite.
		Yet vaterite has been identified in hard tissues of organisms, in gallstones, in contact metamorphic aureoles, in zones of thermal metamorphism, in a meteorite, and in cone-in-cone concretions.
		of New York vaterite is −12.4‰ and that of the Michigan vaterite is −17.6‰, which reflect the oxygen isotopic composition of meteoric freshwater used in drilling.
	www.minersoc.org /pages/Archive-MM/Volume_58/58-392-401.htm (291 words)

	Europa on Earth: The Sulfur Springs of Borup Fiord Pass, Ellesmere Island - Explore the Cosmos \| The Planetary Society
		Vaterite is a rare crystal form of calcium carbonate that is observed in the sulfur springs at Borup Fiord Pass, Ellesmere Island, Canada.
		Vaterite is one of many crystalline forms of calcium carbonate.
		This is only the second location on Earth where vaterite has been found to occur naturally.
	planetary.org /explore/topics/planetary_analogs/borup_fiord.html (1697 words)

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