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Topic: Anhydrite

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	anhydrite.htm (Site not responding. Last check: 2007-10-13)
		Description: Anhydrite is a relatively common mineral usually formed as a chemical precipitate from saline water, forming in limestone, dolostone, and salt beds.
		MARATHON COUNTY: Anhydrite forms rare small inclusions in quartz in pockets in the pegmatites of the Wausau pluton such as are exposed in the "rotten granite" quarries in Sec.
		RUSK COUNTY: Anhydrite and gypsum occur with serpentine, chlorite and carbonates in an unusual metamorphosed mafic tuff in the Eisenbrey deposit, north of Ladysmith (NW sec.
	www.uwrf.edu /~wc01/anhydrite.htm (204 words)

	Anhydrite - Wikipedia, the free encyclopedia
		Anhydrite is commonly associated with calcite, halite, and sulfides such as galena, chalcopyrite, molybdenite, and pyrite in vein deposits.
		Anhydrite is most frequently found in salt deposits with gypsum; it was, for instance, first discovered, in 1794, in a salt mine near Hall in Tirol.
		A peculiar variety occurring as contorted concretionary masses is known as tripe-stone, and a scaly granular variety, from Vulpino, near Bergamo, in Lombardy, as vulpinite; the latter is cut and polished for ornamental purposes.
	en.wikipedia.org /wiki/Anhydrite (375 words)

	Tansill and Salado Formations
		Anhydrite beds are recognized by low response on gamma-ray logs, normal bore-hole diameter on caliper logs (in contrast, halite is commonly strongly embayed because it is dissolved in contact with undersaturated drilling mud), high count on neutron logs, high velocity on sonic logs, and high density log response.
		Anhydrite is typically fairly pure, although bed thickness limits log response from attaining the theoretical values for the thinner beds.
		Anhydrite bed 20 was identified across the entire study area and is distinctive because, in most areas, a thin insoluble residue of mudstone occurs at the base.
	www.beg.utexas.edu /environqlty/salt/salado.htm (1053 words)

	Discussion of Cross Sections
		Anhydrite beds are gradually thicker and more numerous toward the Delaware Basin, but changes in anhydrite-bed thickness are specific to each master cycle, and no evidence for a consistent break is identified within the limits of the techniques used.
		Anhydrite bed 40, which defines the base of the next 100- to 200-ft-thick master cycle, is discontinuous across the basin, and correlation of beds within this interval is therefore somewhat arbitrary.
		Anhydrite bed 50 is continuous and well defined across the Central Basin Platform and Midland Basin and forms the base of the 75-ft-thick master cycle containing three to five halite-mudstone cycles.
	www.beg.utexas.edu /environqlty/salt/discussion.htm (969 words)

	NSDNR, MRB, IC ME 16
		Uncalcined gypsum is also used to a lesser degree as a filler in paints, as a flux in the smelting of certain nickel ores, in the manufacture of crayons, in asbestos packing gaskets and as a sculpture medium when in the form of alabaster.
		Anhydrite bodies usually underlie the gypsum layers and in some instances are exposed at surface.
		Anhydrite is considered to be a Crown mineral in Nova Scotia and therefore is subject to regulation according to the Mineral Resources Act.
	www.gov.ns.ca /natr/meb/ic/ic16.htm (2543 words)

	WHOI : Oceanus : How to Build a Black Smoker Chimney
		Analyses of strontium isotopes from anhydrite grains recovered from various depths in the mound demonstrated that anhydrite was forming from mixtures that ranged from 99.5 percent seawater and 0.5 percent hydrothermal fluid to 52 percent seawater and 48 percent hydrothermal fluid.
		Samples of anhydrite grains recovered from drilled cores were also used to determine the temperature and salinity of fluids at various points within the mound.
		Our fluid inclusion measurements, however, indicated that the anhydrite grains were nearly all precipitating at much higher temperatures, 187°C to 388°C. The logical conclusion is that the seawater and seawater-hydrothermal fluid mixtures that are entering and travelling through the mound are being heated by conduction.
	www.whoi.edu /oceanus/viewArticle.do?id=2400 (2750 words)

	anhydrite
		Anhydrite (CaSO4) is found in evaporite beds throughout the world, often found with other evaporites such as gypsum, sulfur, halite, calcite and dolomite.
		Anhydrite is distinguishable from gypsum by its higher specific gravity and hardness.
		Since anhydrite has such a low permeability when the fluids are being pushed towards the surface they get trapped under the dome and the hydrocarbons float to the top of the fluids and can be extracted more easily.
	www.und.edu /instruct/mineral/geol318/webpage/gorecki (702 words)

	HYDROTHERMAL ALTERATION
		Anhydrite and pyrite are present throughout the drilled section, generally as trace to minor phases.
		A quartz-illite-dominated alteration assemblage with late anhydrite veining is continued in the uppermost section of Hole 1188F (220-280 mbsf), although chlorite and magnetite are rare and corrensite is absent.
		Anhydrite is most abundant as vein and vesicle fill or in breccia cement, but is also observed in thin sections replacing igneous groundmass or plagioclase, particularly in bleached units between 34 and 125 mbsf in Hole 1188A.
	www-odp.tamu.edu /publications/193_IR/chap_03/c3_3.htm (9001 words)

	Rapid setting cementitious composition - Patent 6641658
		In the present invention, an insoluble anhydrous calcium sulfate (anhydrite) is used as the preferred calcium sulfate.
		Anhydrites formed by calcining at low temperatures are able to rehydrate when exposed to moist conditions.
		The mixes containing insoluble calcium sulfate anhydrite (i.e., the mixes with Snow White F&P) yield final set times that are about 1-1/2 to 2 minutes shorter than those for the mixes containing the dihydrate form of calcium sulfate (i.e., the mixes with Land Plaster).
	www.freepatentsonline.com /6641658.html (9193 words)

	SPI Standards for Microanalysis - Minerals - Anhydrite (Site not responding. Last check: 2007-10-13)
		This is a reflected light micrograph of polished, carbon coated anhydrite crystals.
		Anhydrite has 3 perpendicular cleavages, which explains the rectangular crystals and the triangular cavities in the polished surface.
		Anhydrite, as its name implies, has no water and is therefore more stable, thus making it a good standard for sulfate sulfur.
	www.2spi.com /catalog/standards/spiweb/minerals/anhydrite.html (229 words)

	SULFIDE AND OXIDE PETROLOGY
		The magnetite is contained within microveins, associated with bladed anhydrite crystals and variable modes of pyrite; the pyrite to magnetite ratio varies between 0 and 1.
		Marcasite is present with anhydrite and quartz as platelike bronzy radiating crystals on fracture surfaces.
		Anhydrite that is present as thin veins with pyrite crosscuts quartz-1 (Fig.
	www-odp.tamu.edu /publications/193_IR/chap_03/c3_4.htm (2997 words)

	GemRocks: Anhydrite
		The angelite variety of anhydrite, which is widely marketed as from Peru, is apparently recovered from chalky coated nodules from Peru's coastal lowland that is a so-to-speak northern extension of Chile's Atacama Desert.
		Anhydrite can be dyed; indeed, I have been told that some angelite may be white or gray anhydrite that has been dyed blue.
		There is a widespread so-to-speak reciprocal relationship between rock anhydrite and rock gypsum: Some beds of anhydrite appear to have formed by dehydration of rock gypsum; some rock gypsum has apparently had anhydrite rock as a precursor.
	www.cst.cmich.edu /users/dietr1rv/anhydrite.htm (803 words)

	Anhydrite in high sulfur trioxide (SO3)/alkali clinkers: dissolution kinetics and influence on concrete durability
		Anhydrite is present in the clinker only when the quantity of clinker sulfate is higher than the amount that can be combined by the alkali ions as alkali sulfates and calcium langbeinite.
		Thus, the presence of clinker anhydrite is illusive.
		The objective of this study is to establish what would be the effect of anhydrite on durability in the hypothetical case that this phase was present in clinker.
	www.astm.org /JOURNALS/CEMENT/PAGES/117.htm (395 words)

	Ferry Lake, Rodessa, and Punta Gorda Anhydrite Bed Correlation, Lower Cretaceous, Offshore Eastern Gulf of Mexico (Site not responding. Last check: 2007-10-13)
		The anhydrites of Ferry Lake and Rodessa Formations are traceable to the anhydrites of the Punta Gorda and Lehigh Acres Formations of South Florida.
		Anhydrite beds appear to thicken in the central part of the trend interfingering with carbonates of the Lower Cretaceous shelf edge reef.
		Carbonates and anhydrites may be deposited simultaneously with carbonate patchreefs developing on crests of paleo highs with evaporates precipitating out of a hyper-saline solution on the flanks.
	www.gomr.mms.gov /homepg/whatsnew/papers/gp9509.html (567 words)

	Oilfield Glossary: Term 'anhydrite'
		A member of the evaporite group of minerals and the soft rock comprising anhydrite formed by precipitation of calcium sulfate from evaporation of seawater.
		Anhydrite can also form through the dehydration of gypsum, another sulfate mineral found in evaporites.
		Anhydrite may occur as a cap rock above salt domes.
	www.glossary.oilfield.slb.com /Display.cfm?Term=anhydrite (146 words)

	Method for the preparation of fibrous insoluble calcium sulfate anhydrite - Patent 4029512
		The anhydrite occurs in two principal forms, referred to as "soluble" and "insoluble", according to their respective solubilities in water at approximately ambient temperature.
		Due to the high solubility of both the hemihydrate and the soluble anhydrite, however, the use of these fibrous materials as reinforcements has been limited to matrix materials which do not involve the use of water in their formation.
		By the process of this invention, fibrous insoluble anhydrite may be produced to the virtual exclusion of non-fibrous materials, fibrous hemihydrate and/or fibrous soluble calcium sulfate anhydrite.
	www.freepatentsonline.com /4029512.html (2888 words)

	Anhydrite
		Vapor phase chimneys, like Virgin mound, are composed almost entirely of anhydrite and are very fragile.
		The flame-like flickering at Inferno vent is caused by light reflecting off bubbles forming and collapsing in the vent fluid - more evidence of phase separation.
		At the base of Castle vent there is also an active anhydrite chimney.
	www.pmel.noaa.gov /vents/nemo/explorer/concepts/anhydrite.html (168 words)

	Hydrology, Hazards, and Geomorphic Development of Gypsum Karst in the Northern Black Hills, South Dakota and Wyoming
		Gypsum and anhydrite are conspicuous evaporite deposits in four sedimentary rock units in the Black Hills (fig 2).
		Anhydrite, which probably was the original form of calcium sulphate to be deposited in the Spearfish, undergoes about a 40 percent expansion when hydrated to form gypsum.
		As the Black Hills is slowly lowered by erosion, the anhydrite dissolution front in the subsurface Minnelusa moves downdip and radially away from the center of the uplift.
	water.usgs.gov /ogw/karst/kigconference/jbe_hydrologyhazards.htm (4229 words)

	Anhydrite precipitation and the extent of hydrothermal recharge zones at ocean ridge crests
		Anhydrite precipitation and the extent of hydrothermal recharge zones at ocean ridge crests
		We then consider anhydrite precipitation in a buoyancy-driven single-pass model in which the reduction in permeability resulting from anhydrite precipitation exerts a feedback on the flow rate.
		First, the zone of anhydrite precipitation shallows and broadens as the flow rate decreases, thus allowing deeply deposited anhydrite to be preserved temporarily.
	www.agu.org /pubs/crossref/2002/2001JB001289.shtml (392 words)

	A Story in the Rocks
		Anhydrite was a relatively abundant, primary phenocryst phase.
		The presence of anhydrite inclusions in hornblende and plagioclase phenocrysts suggests to Fournelle and others that anhydrite was present in magma at depth and that prehistoric sulfur-rich eruptions might be found by a search for such inclusions.
		Pasteris and others note an absence of anhydrite inclusions in their samples and conclude (on that basis in part) that the dacitic magma reached saturation with respect to a CO O fluid before anhydrite saturation.
	pubs.usgs.gov /pinatubo/section6.html (895 words)

	Research at CRC
		The paradigm that thick anhydrite sections can not form in tidal flat settings because of hydrologic constraints rests on the assumption that most of the evaporites there are displacive in origin.
		Typically, such anhydrite and even massive 'chickenwire anhydrite' are interpreted to represent strongly coalesced nodules whose origin resides in subaqueous gypsum growth even in the absence of evidence for some vertically elongated nodules.
		In the absence of such evidence, we contend that thick beds of 'chickenwire anhydrite' may be purely diagenetic structures attributable to "pacman anhydrite" processes.
	www.crienterprises.com /research_page.html (465 words)

	Magmatic Anhydrite (Site not responding. Last check: 2007-10-13)
		Orthopyroxene megacryst with anhydrite inclusion Which is very difficult to discern, until you have figured out exactly what you are looking for.
		Here the anhydrite is labelled ANin this BSE (backscattered electron image) where the higher atomic number CaSO4 stands out (the round pit is the electron microprobe beam damage).
		The anhydrite has such high order colors under polarized light that it is difficult to distinct from plagioclase.
	www.geology.wisc.edu /~johnf/anhydrite.html (358 words)

	Poikilotopic Anhydrite Enhances Reservoir Quality (Site not responding. Last check: 2007-10-13)
		Anhydrite has long been thought to occlude pore space in dolostones producing a tight, nonproductive carbonate.
		Although this is true for bedded anhydrite and pore filling anhydrite, our study of Permian dolostone reservoirs of West Texas demonstrates that it is not true for poikilotopic anhydrite.
		Poikilotopic anhydrite is the most common form of anhydrite in Permian dolostone reservoirs of West Texas.
	aapg.confex.com /aapg/da2004/techprogram/A87179.htm (306 words)

	ANHYDRITE(Calcium Sulfate)
		Anhydrite is a relatively common sedimentary mineral that forms massive rock layers.
		Good mineral specimens of Anhydrite were extremely rare dispite its common occurrance.
		However, fine specimens of Anhydrite have been found in Mexico and Peru that show good crystal habit, a nice blue color and even a play of light internally in the crystal.
	mineral.galleries.com /minerals/sulfates/anhydrit/anhydrit.htm (238 words)

	Anhydrite (Site not responding. Last check: 2007-10-13)
		Anhydrite is a form of calcium sulphate (CaSO4), with almost the same composition as 'Egyptian alabaster', but without water.
		Anhydrite has also often been called 'blue marble', though not all materials called 'blue marble' are anhydrite.
		Anhydrite was mostly used in the Middle Kingdom (about 2025-1700 BC), and perhaps the Second Intermediate Period, for making cosmetic vessels.
	www.digitalegypt.ucl.ac.uk /stone/anhydrite.html (57 words)

	The World Market for Gypsum and Anhydrite: A 2004 Global Trade Perspective: Industry
		I have developed a methodology, based on macroeconomic and trade models, to estimate the market for gypsum and anhydrite for those countries serving the world market via exports or supplying from various countries via imports.
		The total level of imports and exports on a worldwide basis, and those for each region, is based on a model which aggregates across country markets and projects these to the current year.
		Combined, Chapters 3 and 4 present the complete picture for imports and exports of gypsum and anhydrite to and from all major countries in the world.
	www.mindbranch.com /Gypsum-Anhydrite-Global-R307-5189 (633 words)

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