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Topic: Lamproite

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	Lamproite (Site not responding. Last check: 2007-10-18)
		The rocks commonly are altered to talc with carbonate or serpentine, chlorite, and magnetite.
		The molten material is forced to the surface in volcanic pipes, bringing with it xenoliths and diamonds from the harzburgitic peridotite or eclogite mantle regions where diamond formation is stabilized.
		The economic significance of lamproite became known with the 1979 discovery of the Argyle diamond pipe in Western Australia.
	www.worldhistory.com /wiki/L/Lamproite.htm (290 words)

	Volcanic pipe - Wikipedia, the free encyclopedia
		Volcanic pipes are composed of a deep, narrow cone of solidified magma (described as "carrot-shaped"), and are usually largely composed of one of two characteristic rock types — kimberlite or lamproite.
		These rocks reflect the composition of the volcanoes' deep magma sources, where the Earth is rich in magnesium.
		Lamproite pipes operate similarly to kimberlite pipes, except that the boiling water and volatile compounds contained in the magma act corrosively on the overlying rock, resulting in a broader cone of eviscerated rock (the ejection of this rock also forms a tuff ring, like kimberlite eruptions).
	en.wikipedia.org /wiki/Volcanic_pipe (387 words)

	Lamproite-hosted Diamonds - Mineral Deposit Profiles, B.C. Geologial Survey
		Lamproites are ultrapotassic mafic rocks characterized by the presence of olivine, leucite, richterite, diopside or sanidine.
		If a lamproite magma passes through diamondiferous portions of the mantle, it may sample them and bring diamonds to the surface provided they are not resorbed during ascent.
		In general, clays, particularly smectite, produced during the weathering of lamproites are conductive; and hence, produce strong negative resistivity anomalies.
	www.em.gov.bc.ca /mining/geolsurv/metallicminerals/mineraldepositprofiles/PROFILES/n03.htm (1603 words)

	Diamonds \| American Museum of Natural History
		The complex volcanic magmas that solidify into kimberlite and lamproite are not the source of diamonds, only the elevators that bring them with other minerals and mantle rocks to Earth's surface.
		Kimberlite and lamproite are similar mixtures of rock material.
		The initial stage of the eruption, powered by gases either from the lamproite magma or from boiling ground water, corrodes the hosting rock to form the champagne-glass shape (top).
	www.amnh.org /exhibitions/diamonds/kimberlite.html (279 words)

	Bryson Burke Diamond Corporation: Diamond Exploration and Mining in Canada
		Diamond-bearing lamproites are known from craton margins and adjacent mobile zones that have experienced relatively young and persistent faulting.
		The Prairie Creek lamproite in Arkansas, United States, is diamondiferous and has been mined historically, and the diamondiferous "kimberlites" of India have recently been reinterpreted to be of lamproitic composition.
		The surface configuration of kimberlite and lamproite diatremes may be strongly influenced by local joint patterns in the country rock (Dawson, 1980).
	brysonburke.com /gr_51geology_regional.html (2839 words)

	GeoKansas--Field Trips--South-central KS Guidebook
		Lamproites are pipes of igneous rock, which was highly charged with gas and pushed its way up through faults, fractures, and zones of crustal weakness.
		The lamproite is quarried and hauled to the nearby town of Buffalo, where it is bagged and eventually used as a mineral supplement for cattle feed.
		Surrounding the lamproite are sedimentary rocks that were deposited in Pennsylvanian times, about 300 million years ago, before the lamproite came to the surface.
	www.kgs.ku.edu /Extension/fieldtrips/guidebooks/SCKS/SCKS3.html (962 words)

	Olympus Microscopy Resource Center: Polarized Light Microscopy Gallery - Lamproite
		Lamproite is a type of igneous rock that has recently undergone a massive scientific reexamination, resulting in a comprehensive revision of its taxonomy, as well as related nomenclature.
		The impetus for this sudden, in-depth reassessment was the discovery of economically advantageous diamond-bearing varieties of the rock.
		Lamproites, which typically contain olivine, diopside, leucite, sanidine, or richterite, are currently believed to originate from a partial melting in the lithospheric mantle at depths greater than 150 kilometers.
	www.olympusmicro.com /galleries/polarizedlight/pages/lamproitesmall.html (252 words)

	Petrography and Geochemistry of the Krishna Lamproite Field
		The discovery of this lamproite field is considered very significant from the point of diamond exploration as it is located very close to the famous Golconda Mines along the banks of the River Krishna which yielded many of the celebrated diamonds in the past.
		This field is christened “Krishna Lamproite Field”, in view of the proximity of the lamproite occurrences to the Krishna River having the alluvial placer diamonds.
		The lamproites contain glass, numerous vesicles, and xenoliths of the basement granite-gneiss, dolerite and probably platformal sediments of the Cuddapah Basin, besides exhibiting fragmental and pyroclastic textures suggestive of near-surface emplacement.
	www.bestindia.com /jgsi/Fpaper01.htm (373 words)

	Ellendale (Site not responding. Last check: 2007-10-18)
		The diamond grade of the lava lake material is generally very low and this is interpreted to be due to the diamonds being resorbed by the magma on their “relatively slower” ascent to the surface, and while the magma cools in the lava lake.
		The model of a West Australian lamproite pipe is shown in the figure below and indicates the relative depths of erosion of some of the kimberlites and lamproites of Western Australia.
		The Ellendale lamproite field was known for its leucite lamproites and the recovery of a pyrope garnet in Mount North Creek in 1976 led to follow-up work and the discovery of the diamondiferous Ellendale Pipe 4.
	members.iinet.net.au /~boxer/ellendale.htm (1899 words)

	CVO Menu - America's Volcanic Past - Kansas
		Lamproite and kimberlite found at the surface in Kansas were exposed when the rock above was eroded away.
		Lamproite magma carried it toward the surface, where it is now exposed.
		Unlike most of the surface rocks in Kansas, which are sedimentary in origin, kimberlite is an igneous rock, formed from the cooling of molten magma.
	vulcan.wr.usgs.gov /LivingWith/VolcanicPast/Places/volcanic_past_kansas.html (2333 words)

	TKAS -- Aber and Aber (2001)
		Intrusion of lamproite took place approximately 88-90 million years ago during the mid-Cretaceous, when the present surface was covered by about 1 km of overburden strata.
		The Hills Pond lamproite is located along a steeply dipping fault in the northern portion of a ring-graben structure that surrounds the central uplift of Silver City (fig.
		The general lack of deeply derived xenoliths in the Hills Pond lamproite suggests that intrusive movement was insufficient to carry rock fragments into the sill complex.
	www.emporia.edu /kas/trans104/aber2/aber2.htm (1429 words)

	U-Haul: Arkansas SuperGraphic
		On the surface, the pipe is an 80-acre crater, referred to as Crater of Diamonds.
		Evidence indicates that as the earliest intruded rock neared the surface of the Earth, portions of it were shattered.
		In addition, there are several diamond-bearing lamproite pipes on privately-owned land to the northeast and east of the Crater of Diamonds State Park.
	www.uhaul.com /supergraphics/diamond/statepark3.html (453 words)

	Monroe Minerals Inc. - Diamond Exploration - Tue Nov 22, 2005
		Consequently diamondiferous kimberlites tend to be "on craton", as is the case in Southern Africa where all diamondiferous occurrences are associated with the Kaapvaal Craton.
		Diamonds are found in economic quantities in kimberlite and lamproite, two rock types which have much in common.
		Diamonds eroded from primary kimberlite and lamproite sources may be concentrated under favourable conditions to form valuable secondary deposits, generally referred to as alluvial.
	www.monroeminerals.com /s/DiamondExploration.asp (1999 words)

	Transactions of the Kansas Academy of Science: Limestone Xenoliths in Hills Pond Lamproite, Woodson County, Kansas.@ ... (Site not responding. Last check: 2007-10-18)
		Limestone Xenoliths in Hills Pond Lamproite, Woodson County, Kansas.
		The Hills Pond lamproite is part of a sill complex intruded into the northern portion of the Silver City Dome (Fig.
		This intrusion is related closely in age, composition, and tectonic setting to a nearby intrusion at Rose Dome (Berendsen and Blair, 1991).
	www.highbeam.com /library/doc0.asp?DOCID=1G1:77417384&refid=ip_encyclopedia_hf (242 words)

	Diamond Potential of Wyoming
		Lamproites are potassic mafic volcanic rocks with a unique mineral assemblage, which includes sanidine, leucite, phlogopite, volcanic glass, potassium richterite, and a host of rare accessory minerals.
		Lamproites are much less susceptible to prospecting by this method, as they lack the classical kimberlitic indicator minerals.
		Lamproites and related lamprophyres in eastern Montana are Tertiary in age, and the Leucite Hills lamproites in western Wyoming are very young and dated at only 3.1 to 1.1 Ma.
	www.wsgs.uwyo.edu /metals/legis_rep.aspx (13198 words)

	[No title] (Site not responding. Last check: 2007-10-18)
		sample from the McAllister lamproite was mistakenly examined for diamond content only, not indicator minerals, and there were no microdiamonds observed; which is not surprising due to the size of the sample.
		During the bulk sampling stage of a pipe, diamond grades are usually referred to as "carats per hundred tonne" and an overall grade of less than 1 carat/tonne is common.
		The Company believes that a second diatreme has been identified approximately 4 kilometres from the McAllister lamproite pipe, which suggests that a cluster of pipes may be present in the area.
	www.cdnx.com /data/lcdb/DOCP/MAR2005/%ZYW01!.DOC (508 words)

	COALIFIED TREE XENOLITHS WITHIN THE CRETACEOUS AMERICAN-BLACK LICK LAMPROITE, SOUTHWESTERN ARKANSAS (Site not responding. Last check: 2007-10-18)
		Previous reports document that these lamproites include rare crustal xenoliths of shale, sandstone, quartzite, gabbro, amphibolite, granite, granodiorite and gneiss, and rare mantle xenoliths of dunite, harzburgite, websterite, eclogite and spinel and garnet lherzolite.
		The coalified wood is encased in brecciated lamproite.
		The compressed and coalified wood that is encased in lamproite is very similar to compressed and coalified wood that occurs in the Trinity Formation.
	gsa.confex.com /gsa/2003SC/finalprogram/abstract_49976.htm (373 words)

	Argyle (Site not responding. Last check: 2007-10-18)
		The sandy tuff is composed of juvenile (volcanic) clasts of olivine lamproite, exotic clasts of the sandstone and shale wall rocks to the pipe, set in a matrix of fine grained lamproite volcanic ash and quartz sand.
		Note that the quartz grains are mostly rounded and unbroken, and this is important evidence in the discussion of the physical environment during the formation of the Argyle pipe.
		The lamproite, when it encountered the water saturated sediments of the Carr Boyd Group, would have become potentially very explosive, and only where the overlying lithostatic pressure allowed, the water would have flashed to steam and begun the explosive excavation of the vent.
	members.iinet.net.au /~boxer/argyle.htm (3724 words)

	Superior Mining Corporation - Namaqualand Diamond Project - Tue Nov 22, 2005 (Site not responding. Last check: 2007-10-18)
		The investigation completed to date is at a preliminary stage but sufficient encouragement exists to warrant a further more detail examination of this occurrence to establish if the occurrence is lamproitic, and whether or not it is diamondiferous.
		There is little doubt that the discovery of diamondiferous lamproite in South Africa will have a significant impact on the industry.
		Geochemical and petrological identification by Cinqarnis of the drill material available does suggest similarities to lamproite, and as such cannot be disregarded.
	www.superiormining.com /s/NamaqualandDiamond.asp (591 words)

	Argyle Diamond Pipe, Western Australia (Site not responding. Last check: 2007-10-18)
		By definition, lamproite is a potash and magnesia-rich volcanic or hypabyssal rock with one or more of the following major minerals: olivine, diopside, phlogopite, leucite, amphibole, or thopyroxene,sanidine, and glass.
		Based on their chemistry, lamproite is either basic or ultrabasic (MgO, 16-23%), with high K2O/Na2O (>3), high nickel (560-1080ppm) and high chromium (880-1340 ppm) with high concentrations of Rb, Sr, Ba, Ti, Zr, Nb, Pb, Th, U and light-rare-earth elements.
		The morphology of juvenile clasts and the presence of bedded tuffs, accretionary lapilli, and water escape structures indicated that the Argyle diatreme formed from several phreatomagmatic eruptions.
	volcano.und.nodak.edu /vwdocs/volc_images/australia/argyle/argyle.html (773 words)

	Argyle diamond mine (Site not responding. Last check: 2007-10-18)
		The Argyle diamond mine is also notable for being the first commercial diamond mine exploiting a volcanic pipe of lamproite, rather than the more usual kimberlite pipe.
		The mine is located on a column of olivine lamproite, the first commercial diamond mine (except alluvial mining operations) not located on a kimberlite pipe.
		The lamproite pipe is a volcanic pipe, composed of lamproite that originated as both tuff and magma.
	www.worldhistory.com /wiki/A/Argyle-diamond-mine.htm (1466 words)

	paramount mining corporation limited (Site not responding. Last check: 2007-10-18)
		The tenements are situated in the West Kimberley Lamproite Province as defined by Jaques et al, 1986.
		Two of the larger lamproites, Ellendale Pipes 4 and 9, are the focus of Kimberley Diamond Company NL’s activities in the area.
		The Ullawarra Project consists of two Exploration Licences 09/1019 and 09/1020 and two Exploration Licence Applications 08/1382 and 08/1405 totalling approximately 600 square kilometres, and is located in the Upper Gascoyne area in the southwest of the Pilbara Region.
	www.paramountmining.com /projects.html (1649 words)

	[No title] (Site not responding. Last check: 2007-10-18)
		This pipe has been called Kimberley 20 (being the twentieth lamproite pipe discovered by Kimberley) and is located approximately one kilometre east of Ellendale Pipe 4.
		Definitional drilling on the discovery is continuing, but preliminary work suggests this new pipe has a surface area of approximately one hectare with both tuffaceous and magmatic lamproite identified in drill cuttings.
		The pipe is one of a number of features with magnetic characteristics similar to known lamproites that have been identified within the survey area.
	www.ferret.com.au /articles/b2/0c0088b2.asp (474 words)

	Kennecott Exploration - Live Customized Report - Tue Nov 22, 2005
		Kimberlites and lamproites are igneous rocks derived from great depths within the earth.
		Soils, glacial till, and stream sediments, as well as rock samples, are collected and carefully processed to separate the heavy mineral fraction which is then inspected grain by grain to determine the species and abundance of the indicator minerals and if diamonds are present.
		Most kimberlites and lamproites occur as subvertical, pipe-like or carrot-shaped bodies with diameters ranging from a few meters to several thousand metres.
	www.kennecottexploration.com /s/QwikReport.asp?IsPopup=Y&printVersion=now&XB0Z=16278 (580 words)

	Ashton Mining of Canada Inc. (Site not responding. Last check: 2007-10-18)
		The bid would be submitted following the successful completion and positive results from a 10,000 ton sampling program which is to be carried out under the operatorship of the State of Arkansas Department of Parks and Tourism in the near future, and subject to U.S. Department of Interior approval which is pending.
		The rock type is identical to the the Argyle (AK1) lamproite in Australia which hosts one of the richest and largest diamond mines in the world.
		The "Crater" lamproite which outcrops at surface has an estimated resource potential of 78 million tons to a depth of 600 feet.
	www.ashton.ca /news/1996/news_may_15_1996.html (312 words)

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