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Topic: Andesite

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	Andesite - LoveToKnow 1911
		ANDESITE, a name first applied by C. von Buch to a series of lavas investigated by him from the Andes, which has passed into general acceptance as the designation of a great family of rocks playing an important part in the geology of most of the volcanic areas of the globe.
		The andesites have mostly a porphyritic structure, and the larger felspars and ferro-magnesian minerals are often visible to the naked eye, lying in a finer groundmass, usually crystalline, but sometimes to a large extent vitreous.
		Garnet and sapphire have also been found in andesites, and perhaps have the same signification; a rose-red variety of epidote (withamite) is known as a secondary product in certain andesites (Glencoe, Scotland), and the famous red porphyry (porfido rosso) of the ancients is a rock of this type.
	www.1911encyclopedia.org /Andesite (1114 words)

	Rocks and Minerals Tour: Envi Sci Dept, UVA
		Andesite is an igneous rock, which means it was formed when hot, melted rock and a mixture of crystals deep in the earth cooled and become a solid.
		Andesite is named for the Andes Mountains, which where created due to an andesitic lava flow.
		Texture of andesite is often porphyritic, which means that larger grains are set in with fine or glassy grains in a matrix pattern.
	www.evsc.virginia.edu /tours/rockmin/andesite.shtml (201 words)

	Andesite (Site not responding. Last check: 2007-11-03)
		Andesites occur mainly as surface deposits and, to a lesser extent, as dikes and small plugs.
		There are three subdivisions of this rock family: the quartz-bearing andesites, or dacites, sometimes considered to be a separate family; the hornblende- and biotite-andesites; and the pyroxene-andesites.
		Andesite forms at convergent plate margins and is thought to be the product of partial melts of the water-rich subducting oceanic crustal basalts or of the intervening wedge of lower crustal rocks above the subducting plate.
	geology.csupomona.edu /alert/Igneous/andesite.htm (245 words)

	Andesite: World of Earth Science
		Indeed, andesite is common in all the mountain-building zones that rim the Pacific Ocean.
		Andesites are ordered in three classes according to the identity of their non-feldspar components: from most silicic to most mafic, these are (1) quartz-bearing andesites, (2) pyroxene andesites, and (3) biotite and hornblende andesites.
		Andesite's character usually results from the melting and assimilation of rock fragments by magma rising to the surface.
	science.enotes.com /earth-science/andesite (393 words)

	Andesite (Site not responding. Last check: 2007-11-03)
		Andesite magma is viscous and forms thick lava flows or domes.
		During the Tertiary Period and Pleistocene Epoch andesite was extruded from central volcanoes.
		Andesite is common in many other parts of the world especially, in "the ring of fire" surrounding the Pacific.
	www.casdn.neu.edu /~geology/department/staff/colgan/iceland/minerals/andesite.htm (133 words)

	Andesite - Wikipedia, the free encyclopedia
		A sample of andesite (dark groundmass) with amygdaloidal vesicules filled with zeolite.
		Andesite (IPA: /ˈandəsʌɪt/) is an igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture.
		The quartz-feldspar abundances in andesite and other volcanic rocks are illustrated in QAPF diagrams.
	en.wikipedia.org /wiki/Andesite (566 words)

	Andesite Information Center - andesite porphorlitic
		Andesite is an igneous, volcanic rock, of intermediate andesite composition, andesite porphyry with aphanitic to porphyritic texture.
		Classification andesite manual of andesites may be refined according to the most abundant phenocryst.
		This water is removed from the subducting slab because of the increasing pressure and porphyritic andesite temperature.
	www.scipeeps.com /Sci-Chemistry_Topics_A_-_An/Andesite.html (248 words)

	Identification of Common Rocks - Andesite (Site not responding. Last check: 2007-11-03)
		Andesite is intermediate in composition and colour between felsite and basalt.
		It is the fine-grained volcanic equivalent of diorite and is generally a medium to dark grey rock consisting of mainly plagioclase feldspar and abundant dark minerals.
		Andesites are generally porphyritic, that is, they contain some large crystals floating in a fine-grained matrix.
	www.dslextreme.com /users/bradleygames/rocks/andesite.htm (77 words)

	Mars Pathfinder Page (Site not responding. Last check: 2007-11-03)
		Andesite is a common igneous rock on the earth and its name derives from the Andes mountains which are composed largely of it.
		Andesite is a more complex form of cooled lava than basalt as its composed of more minerals which makes it more viscous (hence it does not easily flow to make Shield Volcanos (Hawaiian Islands) or flat plateaus (Columbia River Plains; Snake River Plains.
		Andesite is an extrusive igneous rock with intermediate chemistry and is composed largely of plagioclase.
	zebu.uoregon.edu /mars/andesite.html (209 words)

	Untitled Document
		Andesite commonly erupts from stratovolcanoes, where they form small-volume flows that typically advance only short distances down the flanks of a volcano.
		The two examples shown here are short andesite flows advancing down the slope of the Lascar volcano in Chile, and the Colima volcano in Mexico.
		Although detached blocks occur on the tops of andesite flows, the flow interior is composed of massive lava which grades downward into an autobrecciated (self-fragmented) basal layer.
	www.geology.sdsu.edu /how_volcanoes_work/andesiterhyolite_lava.html (599 words)

	Andesite (Site not responding. Last check: 2007-11-03)
		Andesite is a fl to gray rock with between 53 and 63 weight percent silica (SiO2).
		Andesites are very common on stratovolcanoes such as Redoubt, where they form both thick lava flows and moderate-sized explosive eruptions of tephra.
		Andesite is one of a suite of rocks formed above Benioff zones.
	www.gly.uga.edu /petrology/redoubt/Andesite.html (118 words)

	Conejo Andesite Breccia (Site not responding. Last check: 2007-11-03)
		In the upper parts of the Conejo Volcanics are lava flow breccias of andesitic composition.
		Andesite is the type of volcanic rock that is found in the Andes volcanoes.
		This photo measures about 15 feet from top to bottom, so the large fragments shown are boulders of andesite that were incorporated into the lava flow.
	www.csun.edu /geology/SMM_Hike/smmhikeday618.htm (55 words)

	Geology 3111 -- Field Trip Guide -- Spring 1999 (Site not responding. Last check: 2007-11-03)
		The largest of the exposed andesite bodies is found on the university campus (up the hill by the Geology building is a good place to view the andesite) and is therefore called the Campus Andesite.
		Characteristic of the andesite is the numerous cracks or joints as well as the yellow-brown color on the weathered surface.
		The yellow color of the andesite is due to the oxidation of the iron minerals in the andesite.
	www.epcc.edu /ftp/Homes/krimkus/fieldtrip.html (2786 words)

	What is Andesite? (Site not responding. Last check: 2007-11-03)
		Andesite is an extrusive igneous rock, light to dark gray, sometimes with reddish to greenish hues; fine-grained, sometimes displays bubbles (vesicular texture), frequently has a brecciated texture (tuff) and sometimes contains phenocrysts of feldspar (Ca and Na rich varieties), quartz, hornblende, pyroxene, and biotite mica.
		Andesite crystals are composed primarily of plagioclase feldspar and one or more of the minerals pyroxene (clinopyroxene and orthopyroxene) and lesser amounts of hornblende.
		Andesite magma commonly erupts from stratovolcanoes as thick lava flows, some reaching several kilometers in length.
	interactive2.usgs.gov /faq/list_faq_by_category/get_answer.asp?id=500 (205 words)

	Orogenic Andesites
		Virtually all andesites are associated with a subduction zone where oceanic crust underthrusts a continent or has done so in the past, the andesites generally becoming more potassic as well as richer in Cs, Rb, Ba, U and Th inland from the subduction zone in regions of thicker crust.
		Andesite series tend to have a highly variable composition, so much so it is difficult to define precisely what we mean by an andesite.
		The ultra-high K rocks near the base are leucitic andesites from Tambora, Muriah and Batu Tara in the Sunda Arc, and from Stromboli, Vulcano in the Aeolian Arc.
	www.geokem.com /Andesite-summary.html (1830 words)

	USGS Photo Glossary: Andesite
		Andesites contain crystals composed primarily of plagioclase feldspar and one or more of the minerals pyroxene (clinopyroxene and orthopyroxene) and lesser amounts of hornblende.
		The word andesite is derived from the Andes Mountains, located along the western edge of South America, where andesite rock is common.
		Andesite was the main rock type erupted during the great Krakatau eruption of 1883.
	volcanoes.usgs.gov /Products/Pglossary/andesite.html (168 words)

	card 9 ANDESITE (Site not responding. Last check: 2007-11-03)
		Andesite forms from the eruption of intermediate-composition lava.
		Such eruptions often begin in an explosive manner, so deposits of layers of pyroclasts are common on and around the volcano.
		Picture 3 illustrates the porphyritic texture which is common in the andesitic flows comprising stratovolcanos.
	seis.natsci.csulb.edu /basicgeo/ANDESITE/ANDESITE.html (203 words)

	PSRD: Using TES to interpret the composition of the Martian surface
		The other way of making andesite is by removing crystals as they form in basalt magma, a process called fractional crystallization.
		For simplicity, I'll stick with andesite.) McSween and members of the Mars Pathfinder team have argued that this process could not produce the large volume of andesite observed (if it is really andesite).
		On the other hand, if andesite formed by fractional crystallization, it ought to be associated more intimately with the basalt, rather than concentrated in different places.
	www.psrd.hawaii.edu /May02/MarsTES.html (2298 words)

	Andesite Data (Site not responding. Last check: 2007-11-03)
		Description: Andesite* is an aphanitic to aphanitic-porphyritic extrusive igneous rock composed primarily of intermediate-composition plagioclase feldspar (which is commonly white), amphibole and various minor minerals such as pyroxene, biotite, a white alkalai feldspar, and perhaps a very small amount of quartz.
		Andesites and diorites (their intrusive equivalent) commonly have a grayish to salt-and-pepper appearance.
		Lighter-toned andesites may be mistaken for rhyolite; however, rhyolite commonly has pink potassium feldspar and always has quartz.
	www.uwm.edu /Course/422-100/Mineral_Rocks/andesite.data.html (122 words)

	ANDESITE - Online Information article about ANDESITE (Site not responding. Last check: 2007-11-03)
		The andesites have mostly a porphyritic structure, and the larger felspars and ferro-magnesian minerals are often visible to the naked See also:
		Sharply-formed little crystals of cordierite are occasion-ally found in andesites (Japan,.
		acid andesites, but is pale brown in the pyroxene-andesites.
	encyclopedia.jrank.org /ANC_APO/ANDESITE.html (1272 words)

	ANDESITE FLOWS AT MT NGAURUHOE, NEW ZEALAND, AND THE IMPLICATIONS FOR POTASSIUM-ARGON - Institute for Creation Research
		The shaded area is the andesite arc, and the inset shows the major components of the boundary between the Australian and Pacific Plates in the New Zealand region (arrows indicate relative motions).
		The Tongariro volcanics unconformably overlie late Miocene marine siltstones beneath Hauhungatahi, and a minimum age for the onset of volcanism is measured by the influx of andesite pebbles in early Pleistocene conglomerates of the Wanganui Basin to the south [15, 43].
		Comparison of the data for each flow with the corresponding data in Table 1 indicates that in their bulk chemistries all the samples analyzed (and thus all the flows) are virtually identical to one another, the trivial differences being attributable to the statistics of analytical errors, sampling and natural variations.
	www.icr.org /research/index/researchp_as_r01 (6320 words)

	purevolume™ \| Andesite
		Recently born from the ashes of another band Andesite continue their journey through the world of rock & roll.
		Although Andesite are a brand new band with only a couple of little tours under their belt so far around regional Victoria, the band have been playing in different formats for years under the name Supercede.
		Having had a number of lineup changes & a progression in the music from somewhere near Motoraces style across to a more Jimmy Eat World oriented sound (for the sake of a comparison) they have ditched most of the old sound & the old name & are starting afresh.
	www.purevolume.com /andesite (316 words)

	GEOLOGY OF THE LATE EOCENE CLARNO UNIT, JOHN DAY FOSSIL BEDS NATIONAL MONUMENT, CENTRAL OREGON
		Its clasts are boulders and cobbles of altered plagioclase porphyritic andesite.
		Thick, autobrecciated andesite flows are present beneath hill 2932 ("Dumbbell Hill") and include several basaltic andesite flows that onlap the highly porphyritic andesite and andesite breccia from the Dumbbell Section (Fig.
		Onlapping the irregular surface of the andesite of Pine Creek is a thick sequence of matrix-supported andesitic debris flows.
	www2.nature.nps.gov /geology/paleontology/pub/grd2/gsa14.htm (4178 words)

	Andesite Line - Wikipedia, the free encyclopedia
		The Andesite Line follows the western edge of the islands off California and passes south of the Aleutian arc, along the eastern edge of the Kamchatka Peninsula, the Kuril Islands, Japan, the Mariana Islands, the Solomon Islands, and New Zealand.
		Within the closed loop of the Andesite Line are most of the deep troughs, submerged volcanic mountains, and oceanic volcanic islands that characterize the Central Pacific Basin.
		Outside the Andesite Line, volcanism is of the explosive type, and the Pacific Ring of Fire is the world's foremost belt of explosive volcanism.
	en.wikipedia.org /wiki/Andesite_Line (271 words)

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