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	Banded iron formation
		Banded Iron Formations are a distinctive type of rock often found in old sedimentary rocks.
		The conventional concept is that the banded iron layers are the result of oxygen released by photosynthetic organisms (i.e.
		The total amount of iron [oxygen?]locked up in the banded iron beds is estimated to be perhaps 20 times the volume of oxygen present in the modern atmosphere.
	www.ebroadcast.com.au /lookup/encyclopedia/ba/Banded_iron_formation.html (248 words)

	Banded iron formation (Site not responding. Last check: )
		Banded Iron Formations are a distinctive type of rock often found in old sedimentary rocks.
		The structures consist of repeated thin layers of iron oxides, either magnetite or hematite, with bands of shale and chert.
		The conventional concept is that the banded iron layers are the result of oxygen released by photosynthetic cyanobacteria, combining with dissolved iron in Earth's oceans to form insoluble iron oxides.
	www.xasa.com /wiki/en/wikipedia/b/ba/banded_iron_formation.html (273 words)

	tScholars.com \| Banded iron formation (Site not responding. Last check: )
		Banded iron formations (also known as banded ironstone formations, or BIFs) are a distinctive type of rock often found in old sedimentary rocks.
		Some of the oldest known rock formations, formed around three thousand million years before present (3 Ga), include banded iron layers, and the banded layers are a common feature in sediments for much of the Earth's early history.
		The conventional concept is that the banded iron layers were formed in water as the result of oxygen released by photosynthetic cyanobacteria, combining with dissolved iron in Earth's oceans to form insoluble iron oxides, which precipitated out, forming a thin layer on the substrate, which may have been anoxic mud (forming shale and chert).
	www.tscholars.com /encyclopedia/Banded_iron_formation (387 words)

	Banded iron formation
		Banded iron formations (also known as banded ironstone formations, or BIFs) are a distinctive type of rock often found in old sedimentary rocks.
		Some of the oldest known rock formations, formed around three thousand million years before present (3 Ga), include banded iron layers, and the banded layers are a common feature in sediments for much of the Earth's early history.
		The conventional concept is that the banded iron layers were formed in water as the result of oxygen released by photosynthetic cyanobacteria, combining with dissolved iron in Earth's oceans to form insoluble iron oxides, which precipitated out, forming a thin layer on the substrate, which may have been anoxic mud (forming shale and chert).
	encycl.opentopia.com /term/Banded_iron_formation (360 words)

	* Banded Iron Formation - (GIS): Definition
		Rock consisting of alternating light and dark layers of iron-rich chert (the dark layers have more iron minerals) formed from 3.8 to 1.7 billion years ago.
		banded iron formation (BIF) A sedimentary mineral deposit dominated by iron oxides, carbonates, or silicates that were deposited chemically from seawater.
		Starting about 4 billion years ago, much of this oxygen combined with iron that precipitated along with silicates to form the banded iron formation (BIF) rock that are a hallmark of deposits until about 2 billion years ago.
	en.mimi.hu /gis/banded_iron_formation.html (151 words)

	Harold Lloyd James, June 11, 1912–April 2, 2000 \| By Paul Barton \| Biographical Memoirs
		James showed that all these rock types may have been locally, and with varying intensities, metamorphosed and/or hydrothermally altered to yield different textures and mineral assemblages, yet for the most part, retaining distinctive features that enable their protoliths to be identified, thereby making possible the conceptual reconstruction of the parent sedimentary basins.
		The family moved to Iron River, Michigan, and remained there until 1954; it was an excellent environment in which to raise children and offered an opportunity for Hal to hone his skills in hunting, with the bow as well as rifle.
		The second, in 1955, defined the nodal pattern of metamorphism in northern Michigan and established the relation between the metamorphic grade and the character of the iron ore. The third, in 1958, assembled and clarified the stratigraphic relations among the diverse older Precambrian rocks throughout northern Michigan.
	www.nap.edu /html/biomems/hjames.html (3086 words)

	Banded iron formation Summary
		Algoma-type banded iron formations were deposited as chemical sediments along with other sedimentary rocks (such as greywacke and shale) and volcanics in and adjacent to volcanic arcs and spreading centers.
		Banded iron formations (also known as banded ironstone formations, or BIFs) are a distinctive type of rock often found in old sedimentary rocks.
		The conventional concept is that the banded iron layers were formed in water as the result of oxygen released by photosynthetic cyanobacteria, combining with dissolved iron in Earth's oceans to form insoluble iron oxides, which precipitated out, forming a thin layer on the substrate, which may have been anoxic mud (forming shale and chert).
	www.bookrags.com /Banded_iron_formation (1121 words)

	Banded Iron Formation - PartI
		Banded iron formation-hosted gold deposits consist of gold intergrown with quartz and/or sulphide minerals in deformed and structurally complicated iron-rich sedimentary rocks.
		In the case of oxide-facies BIF, primary hematitemagnetite is replaced by pyrite-pyrrhotite with minor siderite (iron carbonate).
		In this case, the gold in the BIF would be classified as stratiform (truly bedded and related to the deposition of the host unit), based on its original pre-deformation form.
	www.macdonaldmines.com /banded_1.htm (549 words)

	Banded Iron Formation
		Banded iron formation is iron rich chert (cryptocrystalline silica (SiO
		The banded colours, usually on a cm scale are due to differing amounts and oxidation states of Fe-containing minerals: haematite, magnetite, grunerite, limonite, siderite and sometimes pyrite.
		BIF is not forming today and although it can be found in the Archean, most deposits of BIF were formed around 2 billion years ago.
	www2.bc.edu /~strother/GE_146/lectures/pics21/bif.html (76 words)

	Uranium and Polymetallic Sulphide Mineralisation in the Banded Iron Formation at Udaisagar
		Thinly laminated, pelagic, Banded Iron Formation (BIF) of Lower Proterozoic Aravalli Supergroup lies close to basement granite and phyllites over a stretch of 5 km along the Udaisagar-Kalamagra tract, Udaipur district, Rajasthan.
		Banded Haematite Quartzite (BHQ), a part of BIF, is 5-30 m in width and is intercalated with carbonaceous shale/phyllites.
		BIF exposed at Udaisagar-Kalamagra tract forms a linear belt and resembles the early Proterozoic Lake Superior type in its geochemical signatures.
	www.bestindia.com /jgsi/Jun_p07.htm (255 words)

	Tungabhadra Minerals Private Ltd.
		Iron ore is preserved in the synclinal trough of the folds.
		The ore formations are marked by fairly reverse structural deformation that has resulted in steeply dipping, long and regular iron ore bands occurring along the crest of the hill range.
		Band one has a 750 meter running strike length with a width of 60 meters; Band two runs to a length of 150 meters with an average width of 55 meters.
	www.tml.co.in /geology.htm (1111 words)

	Banded iron formation - Definition, explanation
		The structures consist of repeated thin layers of iron oxides, either magnetite or hematite, with bands of shale and chert.
		The conventional concept is that the banded iron layers are the result of oxygen released by photosynthetic cyanobacteria, combining with dissolved iron in Earth's oceans to form insoluble iron oxides.
		The total amount of oxygen locked up in the banded iron beds is estimated to be perhaps 20 times the volume of oxygen present in the modern atmosphere.
	www.calsky.com /lexikon/en/txt/b/ba/banded_iron_formation.php (280 words)

	siderite.htm
		ASHLAND COUNTY: Siderite is a common component of the Ironwood Banded iron formation, exposed throughout the Gogebic Range.
		DODGE COUNTY: Siderite is a sparse component of the oolites and matrix of the Neda iron formation, as mined in the east 1/2 NW sec.
		IRON COUNTY: Siderite is a common component of the Ironwood Banded iron formation, exposed throughout the Gogebic Range.
	www.uwrf.edu /~william.s.cordua/siderite.htm (681 words)

	Iron Pot - Scotch
		Iron formations and pyritic stockwork quartz veining are also known to occur in this area.
		The IRON POT property was staked after prospecting for banded iron formation gold, in an area considered favorable for this type of deposit model.
		Banded iron formation-hosted gold deposits consist of gold inter-grown with quartz and/or sulphide minerals in deformed and structurally complicated iron-rich sedimentary rocks.
	www.richriver.bc.ca /id69.htm (2917 words)

	Lake Superior iron formation (Site not responding. Last check: )
		Iron formations which formed during Middle Precambrian time (about 2,000 million years ago) and were first described in the Lake Superior region.
		These iron minerals could no longer remain in solution and precipitated from the sea water in varying proportions with quartz, thus producing banded iron formation.
		These iron formations are abundant in the present day Lake Superior region and may be best known in Minnesota as the source of taconite on the Mesabi Iron range.
	www.geo.umn.edu /mgs/cuyuna/lsif.html (131 words)

	Geological Essay Text Apr 2003
		Existence of banded iron formations indicates that iron ions dissolved in seawater were oxidized in the wake of a certain event occurred on a global scale.
		Large scaled banded iron formations existing worldwide are the proof that oxygen had come to exist on earth in a limited period of time.
		Iron ores are being carried from the mine to a nearby port regularly.
	www.ersdac.or.jp /Others/geoessay_htm/geoessay_e/geo_text_04_e.htm (1339 words)

	The Guide to Rocks and Minerals - Banded Iron Formation
		Banded Iron formations (BIFs) are among the oldest rocks on Earth.
		The formation of BIFs started in the Proterozoic area around 1.8-2.5 billion years ago, at the time when Earth's atmosphere was devoid of oxygen and consited mainly of methane.
		Some scientists belive that the formation of banded iron deposits originated in an upwelling continental shelf setting and this can be linked to geologic phenomena such as sea transgression (a relative rise in sea level resulting in marine strata being deposited over terrestrial strata).
	www.rockcollector.co.uk /infocus/bif.asp (454 words)

	Mineralogy and Petrology of the Contact Metamorphosed Amphibole Asbestos-bearing Penge Iron Formation, Eastern ...
		According to Beukes, (1978, 1983), the Penge Iron Formation is stratigraphically equivalent to the crocidolite-bearing Asbesheuwels Subgroup, comprising the Kuruman and Griquatown Iron Formations, in Griqualand West (refer to Fig.
		Correlative units in the Kuruman Iron Formation are composed of magnetite-siderite-greenalite banded iron-formation (Beukes, 1978, 1983).
		Ferri-annite in the Penge Iron Formation coexists with quartz, riebeckite, magnetite, carbonates (mostly ankerite-dolomite and calcite), grunerite and fayalite.
	www.oxfordjournals.org /our_journals/petroj/online/Volume_38/Issue_05/html/ega032_gml.html (9524 words)

	McGraw-Hill AccessScience: Banded iron formation
		anded iron formation is a sedimentary rock that was commonly deposited during the Precambrian.
		Banding is produced by the concentration of these two chemical components into layers about 1-5 cm (1/2-2 in.) thick; typical banded iron formation consists of pale silica-rich cherty bands alternating with fl to dark red iron-rich bands (
		These contrasting layers are sharply defined, so that the rock has a striped appearance; banded iron formation is normally a hard, tough rock, highly resistant both to erosion and to breaking with a hammer.
	www.accessscience.com /Encyclopedia/7/75/Est_757494_frameset.html?doi (207 words)

	NAI: News Stories
		Iron in oxidized or "rusted" state in a sedimentary banded iron formation.
		The rocks in question appear to be a banded iron formation, or BIF, from Akilia Island in West Greenland.
		Iron and oxygen present in the oceans combined to form rust, which settled to the sea floor in layered sediments.
	nai.arc.nasa.gov /news_stories/news_detail.cfm?article=old/lifebombard.htm (1419 words)

	[No title]
		BIFs, by virtue of their large spatial extent and distinct but narrow temporal extent, are certainly exciting.
		BIFs are generally thicker and more laterally extensive in the Late Archaean to early Proterozoic basins than in older greenstone belts (Klein and Beukes, 1992), representing a transition to Superior-type BIF deposition.
		Ferrous iron in solution is highly susceptible to oxidation, mainly due to its reaction with rocks, dilution by meteoric waters and the buffering effect of carbonates and silicates.
	earthweb.ess.washington.edu /~jelte/essays/BIFs.doc (5526 words)

	Past Student Research: Karl Wegmann
		The mineralogy is similar to that of iron formation rocks described by Immega and Klein (1976) from similar locations and elsewhere in the southern Tobacco Roots.
		Banded garnet gneiss outcrops in the northern portion of the PMMMS.
		This along with the fact that there are minor amounts of marble, quartzite and iron formation in the PMMMS is evidence that they may in fact be lateral facies variations on the same unit.
	www.whitman.edu /geology/wegman.html (2142 words)

	Banded Flint (aka Striped Flints)
		For example, pyrite and marcasite are both iron sulfide.
		Iron reacts with rare earth metals to form hard intermetallic compounds similar to those in neodymium magnets; such magnets are also known to generate sparks quite easily when broken.
		The exact mode of formation of flint is not yet clear or agreed but it is thought that it occurs as a result of chemical changes in compressed sedimentary rock formations, during the process of diagenesis.
	bandedflint.com (4399 words)

	banded iron formation
		Most deposits of this type were laid down about 2.5 billion years ago at a time when Earth's atmosphere still consisted mainly of nitrogen and carbon dioxide.
		Oxygen given off as a waste product by early photosynthetic bacteria immediately bonded with the abundant dissolved iron to yield minerals like magnetite and hematite.
		Banded iron formations (BIFs) occur worldwide and give rich iron ore deposits in parts of Minnesota and Michigan.
	www.daviddarling.info /encyclopedia/B/BIF.html (110 words)

	BANDED IRON FORMATION
		Banded Iron Formations are thought to have formed from the precipitation of iron from the Earth's ancient oceans. Photosynthetic bacteria produced, for perhaps the first time in the young Earth's oceans, free oxygen which oxidized the dissolved iron that existed abundantly at the time.
		BIF is the proof of this transformation when it was under way. The conditions to form BIF, dissolved iron and episodic oxygenation, existed early in Earth's history and then once the Earth's oxygen levels stabilized the conditions for banded iron formation all but ceased to exist.
		Banded iron formations are found in the continental shield of all continents of the world.
	www.galleries.com /rocks/bif.htm (397 words)

	northernminer.com - The Northern Miner - 12/5/2007
		Banded iron formation-hosted gold deposits consist of gold intergrown with quartz and/or sulphide minerals in deformed and structurally complicated iron-rich sedimentary rocks.
		The banded iron formation (BIF) host rocks are thinly layered (layers can be measured in centimetres) sedimentary rocks with alternating iron-rich and cherty (silicious) layers; the BIFs can have considerable lateral extents.
		Banded iron formation-hosted gold deposits are important in terms of Canadian and U.S. gold production, as illustrated by mines such as the Lupin and Musselwhite in Canada and the Homestake in South Dakota.
	www.northernminer.com /Tools/Geology101/geo101pg3.asp (2407 words)

	Early Proterozoic Geologic History of Minnesota
		Iron formations of the same age are found in Labrador, western Australia, Russia, Venezuela, Brazil and Africa, suggesting a global atmospheric change richer in free oxygen at this time.
		Iron is very soluble under reducing conditions and insoluble under oxygen-rich conditions, and therefore, behaves just the opposite of uraninite, dissolving in oxygen-poor water and precipitating in oxygen-rich water.
		After 1.8 billion years, banded iron formations are rare, but terrestrial red-beds are common for the first time, suggesting that iron is being oxidized and precipitated in soils and rocks on land in the source area of sediments instead of being dissolved and carried into the oceans in its unoxidized form.
	www.winona.edu /geology/MRW/EarlyProterozoic.htm (1963 words)

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