
	Where results make sense

Topic: Aphanitic

In the News (Wed 15 Feb 12)

EXECUTIVE POWER

Iran

ANALYSIS

Pakistan

Family compact

	Igneous rock - Wikipedia, the free encyclopedia
		In a simplified classification, igneous rock types are separated on the basis of the type of feldspar present, the presence or absence of quartz, and in rocks with no feldspar or quartz, the type of iron or magnesium minerals present.
		The most important distinction in igneous rocks is texture, which is the physical character of the rock, including the size, shape, orientation, and distribution of grains and the intergrain relationships.
		Porphyritic textures are an intermediate situation between the previous two: the groundmass of the rock has an aphanitic texture, but crystals (termed in this particular occurrence as phenocrysts) are visible to unaided eye.
	en.wikipedia.org /wiki/Igneous_rock (1589 words)

	ign_lab (Site not responding. Last check: 2007-10-08)
		Aphanitic rocks are composed predominantly of crystals too small to be seen with the unaided eye.
		Gas cavities are separated by walls of aphanitic material that may be several mm or cm thick.
		Although aphanitic rocks have the same range of mineral compositions as their phaneritic counterparts, their minerals are microscopic and generally not visible in hand specimens.
	www.salemstate.edu /~lhanson/gls100/lab_rocks/ig_lab.htm (1351 words)

	Igneous Rock Texture
		Aphanitic rock is igneous rock in which the grain or crystalline structure is too fine to be seen by the unaided eye.
		Since the crystals of individual minerals cannot be easily resolved for classification, aphanitic rocks are classified in general terms like light, intermediate or dark in color.
		The presence of voids called vesicles is common in aphanitic rock since the condition of cooling rapidly may be associated with the upper portion of lava flows.
	hyperphysics.phy-astr.gsu.edu /hbase/Geophys/texture.html (421 words)

	chapt03
		Rhyolite is the aphanitic (fine-grained) extrusive equivalent of granite.
		Andesite is the aphanitic (fine-grained) extrusive equivalent of diorite.
		Basalt is the aphanitic (fine-textured) extrusive equivalent of gabbro.
	www.csun.edu /~vcgeo004/chapt03.html (514 words)

	Encyclopedia: Dacitic (Site not responding. Last check: 2007-10-08)
		It has an aphanitic to porphyritic texture with quartz as rounded, corroded phenocrysts, or as an element of the ground-mass.
		Rhyolite Rhyolite is an igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture.
		Trachyte is an igneous, volcanic (extrusive) rock, with aphanitic to porphyritic texture.
	www.nationmaster.com /encyclopedia/Dacitic (925 words)

	Igneous Rock Textures
		A good rule of thumb is that fine grained or aphanitic rocks are dull appearing, while phaneritic rocks are brighter or shinier (of course be careful of a glassy rock like obsidian).
		Aphanitic texture consists of small crystals that cannot be seen by the eye with or hand lens.
		Aphanitic rocks are characterized by textures in which the mineral grains are not visible to the eye so they generally look rather like a blank slate.
	geology.csupomona.edu /alert/igneous/texture.htm (684 words)

	TEXTURES REFERRING TO THE GRANULARITY OF (Site not responding. Last check: 2007-10-08)
		Aphanitic refers to a rock, which is so fine grained, that individual crystals cannot be discerned without a microscope.
		in the figure, both the phenocrysts and the groundmass are fine grained (aphanitic).
		and phaneritic-porphyritic term describes, respectively some situations where the phenocrysts are phaneritic but the groundmass is aphanitic and where both groundmass and phenocrysts are phaneritic.
	www.metu.edu.tr /home/www64/geoweb/igneous-granularity.htm (465 words)

	Aphanite - TheBestLinks.com - Aphanitic, Crystal, Igneous rock, Basalt, ...
		Aphanitic, Aphanite, Crystal, Igneous rock, Basalt, Rhyolite, Dacite, Trachyte...
		An aphanite is an igneous rock with a fine-grained structure.
		Aphanites are commonly porphyrites, having large crystals embedded in the fine groundmass.
	www.thebestlinks.com /Aphanitic.html (108 words)

	Igneous Rocks Kit (Site not responding. Last check: 2007-10-08)
		Anorthosite is a coarse-grained crystalline rock consisting of 95% soda-lime feldspars with polysynthetic twinning.
		Andesite Porphyry is a light colored rock containing feldspar crystals in an aphanitic groundmass of plagioclase feldspar and hornblende, biotite or augite.
		Aphanitic Texture (Microcrystalline)-Mineral grains too small to be seen by the naked eye.
	members.cox.net /bennowak/solidearth/sela/igrxkit.htm (331 words)

	IGNEOUS PETROLOGY (Site not responding. Last check: 2007-10-08)
		The basement units are typically nonvesicular, aphyric to moderately phyric, aphanitic to fine-grained basalts that are slightly to moderately altered (see "Alteration").
		Immediately adjacent to the glassy rims are aphanitic zones, 1-2 cm wide; rare vesicles elongated perpendicular to the pillow rims are present immediately adjacent to the aphanitic zone.
		The average grain size of the fine-grained patches is approximately the same as that of the fine-grained basalt (0.3-0.5 mm).
	www.ga.gov.au /odp/publications/192_IR/chap_06/c6_5.htm (903 words)

	Germany Valley Ordovician Carbonates Strat Column Photographic Report
		60 feet of interbedded pale to medium grey aphanitic limestone, and darker grey pelmicrite and bioclastic limestone.
		Is usually mined where it is found, and is a pale to medium grey aphanitic limestone (dove-grey vaughnite), normally massive to thick-bedded.
		aphanitic - from aphanite, a dense, homogeneous rock with constituents so fine that they cannot be seen by the naked eye.
	www.psc-cavers.org /articles/GVstratcolumn.html (1400 words)

	a12 Classification of igneous rocks
		Field, and laboratory, observations have shown that the size of igneous rock crystals depends on the rate of cooling, the composition (which determines viscosity at given temperatures), and the volatile (mostly water, carbon dioxide, sulfur, chlorine, and fluorine) content.
		Crystalline volcanic rocks are most often fine grained (aphanitic) but thick flows of molten lava can solidify as lava rock with coarsely grained interiors.
		Should decisive field relationships be absent, aphanitic- and phaneritic igneous rocks are deemed to be volcanic and plutonic respectively.
	www.geowords.com /histbooknetscape/a12.htm (669 words)

	Igneous Rocks
		Describe how the rate of cooling influences the size of crystals in igneous rocks.
		List the different igneous rock textures (aphanitic, phaneritic, porphyritic, pegmatitic, vesicular, glass, and pyroclastic) and explain their origins.
		The groundmass may be either aphanitic or phaneritic.
	www.gpc.edu /~pgore/geology/geo101/igneous.htm (614 words)

	Ignimbrite
		Fine-grained to aphanitic, buff to dark brown compact rock with paralle streaks or lenticles of fl gass.
		Fine-grained to aphanitic and flow foliation is often present.
		Sillar, which is poorly consolidated rock of same origin as ignimbrite but in which pumice blocks have not collapsed to form plates of fl glass and which is poorly sorted.
	www.geocities.com /RainForest/Canopy/1080/ignimbrite.htm (72 words)

	Uwharries Lithics Conference: Dr James Stoddard
		And there are separate sets of names for the coarse-grained or phaneritic rocks and the fine-grained volcanic rocks, aphanitic rocks.
		So in other words, if a rock has a very fine-grained aphanitic groundmass and phenocrysts of quartz in it, we can base the name on the fact that it has quartz phenocrysts.
		Once it becomes recrystallized to the point that it has a metamorphic texture, that is not igneous, but we still think it was a basalt originally then we'll start calling it a greenstone or something else.
	www.arch.dcr.state.nc.us /uwharrie/stoddard26am.html (4200 words)

	Metamorphic Petrography
		Initial field classification of the metamorphic rocks was based on textures and mineral compositions recognizable in hand specimen.
		Texturally, the blastoporphyritic rocks were differentiated using the size of the phenocrysts and whether or not the matrix was aphanitic.
		The darkness of the rock was used as a semi-quantitative measure of the aphanitic nature of the matrix.
	www.angelfire.com /extreme4/lkrwork/c26.htm (416 words)

	PRR-03721 volcanic porphyry (Site not responding. Last check: 2007-10-08)
		volcanic porphyry, with gray aphanitic groundmass and phenocrysts of feldspar and quartz
		Main rock type locally grades into 2-6" lenses of white to green white, porphyritic rock with aphanitic groundmass and quartz phenocrysts.
		Textures and colors vary from fl to pale gray white and from aphanitic to porphyritic.
	www-bprc.mps.ohio-state.edu /rr/samples/exhibit1/e13731a.htm (113 words)

	ignchrt.html (Site not responding. Last check: 2007-10-08)
		In a porphyritic andesite, for instance, 75% of the volume of the rock may be aphanitic (<1/16 mm) and the remaining 25% of the volume may be represented by a population of larger (~8 mm) crystals (e.g., hornblende, plagioclase).
		In volcanic rocks, the small grain-size part of the rock (matrix) is aphanitic, and large grain-size crystals are generally phaneritic.
		In plutonic rocks, the small grain-size part of the rock (matrix) is phaneritic, and the large grain-size crystals just larger.
	www.appstate.edu /~abbottrn/rck-id/ignchrt.html (519 words)

	Identification of Igneous Rocks (Site not responding. Last check: 2007-10-08)
		There are five basic textural types, phaneritic, aphanitic, glassy, vesicular and fragmental.
		But in reality, we treat porphyritic textured rocks as either phaneritic or aphanitic depending on size of the smallest of the two different grain sizes.
		Most porphyritic textures rocks end up in the aphanitic group, but rarely we do see a porphyritic phaneritic rock.
	geology.csupomona.edu /alert/igneous/igneousid.htm (155 words)

	GO 547 Igneous Rock Classification
		Aphanitic -- Small crystals that cannot be seen by the eye with or without a 10-power hand lens.
		This texture implies two-stage cooling--an early stage of slow cooling in which the phenocrysts grow, followed by a later stage of rapid cooling that forms the matrix.
		The color index is more difficult to apply to aphanitic rocks, as their hue and brightness vary considerably.
	academic.emporia.edu /aberjame/field/rocky_mt/igneous.htm (837 words)

	Mt. Rogers Formation
		Buzzard Rock Member: The Buzzard Rock Member (300 meters thick) is composed of a maroon or purple-gray aphanitic rock with phenocrysts of perthitic alkali feldspar and plagioclase.
		Whitetop Rhyolite Member: The Whitetop Rhyolite Member (500 meters thick) is an aphanitic gray-purple rock that is phenocryst poor (0-10%).
		Wilburn Rhyolite Member: The Wilburn Rhyolite Member (750 meters thick) is a grayish purple aphanitic rock with phenocrysts of perthite and quartz making 30% of the rock.
	www.radford.edu /%7Efldsch/RUFieldschool/formationpages/Mt.%20Rogers%20Fm/MtRogers.html (972 words)

	ignchrt.html (Site not responding. Last check: 2007-10-08)
		Foliation is common in aphanitic as well as phaneritic metamorphic rocks.
		Banding means that the rock consists of alternating, thin layers (typically 1 mm to 1 cm) of two different mineral compositions.
		Gneiss is normally phaneritic, but in some cases the layers are aphanitic.
	www.appstate.edu /~abbottrn/rck-id/mtmchrt.html (540 words)

	[No title]
		APHANITIC TEXTURE - Igneous rocks that form on the earth's surface have very fine-grained texture because the crystals are too small to see without magnification.
		Mafic rocks (basalt and gabbro) are very dark in color, and very dense because of their high iron content.
		ANDESITE is a medium gray, fine grained rock of volcanic origin, named after the Andes Mountain, but is abundant in all volcanic regions associated with subduction zones (where crust is sinking and partially remelting - example: volcanos associated with the Pacific "Ring of Fire").
	www.geo.hunter.cuny.edu /bight/chap3.html (857 words)

	[No title] (Site not responding. Last check: 2007-10-08)
		By definition, an aphanitic texture means that individual mineral crystals are present but in particles so small that they cannot be identified with the naked eye or a 10x hand lens.
		Therefore, for the obsidian, the pumice and the aphanitic groundmass, NA was the appropriate answer.
		Many of these samples were the same ones you examined in the igneous rock lab i.e.
	www.science.uwaterloo.ca /~fjgervai/page7.html (157 words)

	PRR-03653 igneous (Site not responding. Last check: 2007-10-08)
		green flinty aphanitic rock that locally contains clasts of dacite; honeycombed with vesicles that are elongated vertically and up to 4" long, filled with dark green material
		Rock is porphyritic dacite, dark green gray, aphanitic flinty groundmass with ~ 15-20% phenocrysts of K-spar and quartz.Clasts are of same dacitic rock that the enclosing matrix is. Prominent benches on hillside are joint planes N40°W, 5°NE.
		In one spot it looks like a dike - sharp chilled margin contact between aphanitic rock and porphyritic dacite.
	www-bprc.mps.ohio-state.edu /rr/samples/exhibit1/e13663a.htm (117 words)

	Fine-Grained (Aphanitic) Textures
		If you plan on taking more geology classes, it is worth memorizing the word aphanitic (meaning grains too small to easily see).
		Aphanitic textures occur in combination with other textures.
		For example, many vesicular or amygdaloidal rocks are also aphanitic, and many volcanic rocks show a porphyritic texture with a fine-grained groundmass.
	www.pitt.edu /~cejones/GeoImages/2IgneousRocks/IgneousTextures/2FineGrained.html (219 words)

	Mineral Resources Data System
		Extrusive rock having a texture which is similar to that of glass or quartz and developed as a result of rapid cooling of the lava without distinct crystallization.
		A glass-rich pyroclastic rock that has been indurated by the welding together of its glass shards under the combined action of the heat retained by particles, the weight of the overlying material, and hot gasses.
		A light-colored, fine-grained or aphanitic extrusive or hypabyssal rock, with or without phenocrysts and composed chiefly of quartz and feldspar.
	tin.er.usgs.gov /metadata/mrds.faq.html (6867 words)

	Igneous Rocks Properties
		Made up of tiny crystals, which can only be identified using a microscope or powerful hand lends, they give the rock a flow texture (eg.
		Composed of volcanic glass, sometimes the glass may be streaky, due to aphanitic bands, and may often contain micro crystals of feldspar (eg.
		These are volcanic rocks in which the magma has been shattered by an explosive eruption and so may consist of tiny silvers of volcanic glass, fragments of pumice, crystals or fractured rock; they may be unconsolidated or cemented together when fresh and altered to clays by weathering when not.
	www.geocities.com /RainForest/Canopy/1080/igneous_properties.htm (208 words)

Try your search on: Qwika (all wikis)