• The Texture of Igneous Rocks

    Porphyritic textures develop when conditions during cooling of a magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a fine grained (aphanitic) matrix. The result is an aphanitic rock with some larger crystals (phenocrysts) imbedded within ...

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  • What is porphyritic texture?

     · Basalt has a finegrained mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow; it is often porphyritic, containing larger crystals (phenocrysts) formed prior to the extrusion that brought the magma .

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  • METAMORPHIC ROCK CHART

    If a rock falls in one of the above egories on the chart but is porphyritic (visible crystals in a fine grained groundmass or matrix) it is given a compound name, for example, granite porphyry (or porphyritic granite), and basalt porphyry (or porphyritic basalt). For more information see the Geology of Michigan, 1991; Dorr Eschman, University of Michigan Press, Ann Arbor, .

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  • Harmful Materials in Scoria Lightweight Aggregates, Harrat ...

    The vesicular porphyritic basalt is the most abundant rock type in the studied scoria. It is composed from glassy groundmass contains abundant plagioclase and clinopyroxene phenocrysts with less frequent opaques (magnetite and ilmenite). The vesicular texture is the most dominant where the vesicles are filled with calcite and quartz (Fig. 5C). The plagioclase is present either as finegrained ...

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  • Earth Science: MD Chapter 3

    Porphyritic andesite: Porphyritic basalt: Fine grained and vesicular or amygdaloidal: Vesicular or amygdaloidal andesite: Vesicular or amygdaloidal basalt: Pyroclastic: Rhyolite tuff or breccia: Andesite tuff or breccia: Basalt tuff or breccia: Glassy: Obsidian: Obsidian: Glassy with many small vesicles: Pumice : Pumice: Scoria: Last modified: Mon Jan 29 14:10:54 CST 2001 ...

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  • Equilibrium between Clinopyroxene and Host Rocks ...

    There is a liner correlation present in composition of clinopyroxenes (including phenocryst, microcrystal and xenocryst) from coarse porphyritic basalts, pillow or fine porphyritic basalts to amygdaloidal basalts. All the clinopyroxenes, except the clinopyroxenes in mantle xenoliths, show a similar pattern of trace elements and REE, which indies that they are likely products .

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  • Basalt | SpringerLink

    Basalt is a finegrained, darkcolored mafic volcanic rock composed of plagioclase, ortho or clinopyroxene, minor FeTi oxides, with or without olivine. Largegrained (porphyritic) samples contain large crystals (phenocrysts) of olivine, pyroxene, or plagioclase dispersed in a finegrained matrix glassy matrix, or groundmass. Gasrich samples contain abundant vesicles. Basalt contains 45–52 ...

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  • Harmful Materials in Scoria Lightweight Aggregates, Harrat ...

    The vesicular porphyritic basalt is the most abundant rock type in the studied scoria. It is composed from glassy groundmass contains abundant plagioclase and clinopyroxene phenocrysts with less frequent opaques (magnetite and ilmenite). The vesicular texture is the most dominant where the vesicles are filled with calcite and quartz (Fig. 5C). The plagioclase .

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  • Performance characteristics of tunnel boring machine in ...

    Major mineral composition of fine grained basalt and porphyritic basalt constitutes plagioclase (4045%), pyroxene (1520%), glass (1015%), iron oxide (810%), and secondary calcite (710%), and groundmass was composed of plagioclase, pyroxene and glass. The mineral contents of the amygdaloidal basalt and tuff breccia are plagioclase (35%), devitrified glass (30%), pyroxene (20%), .

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  • Basalt Textures

    Basalt has several textural varieties such as glassy, massive, porphyritic, vesicular, scoriaceous. In the Keweenaw we can subdivide textures into three types, following Huber's example: Porphyrite, Trap and Ophite, applies ideally to Isle Royale, but works for the PLV on the Keweenaw too. Porphyrite or porphyritic basalt is characterized by obvious crystals, usually .

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  • Aunt found this rock, what is it? My best guess right now ...

    It looks like porphyritic basalt. My answer is based on the blocky characteristics of the white mineral (feldspar) in a dark matrix (black finegrained material). My be given a different name depending on chemical makeup. 8. Share. Report Save. level 2 · 4y. geo, geochem. Looks intrusive. Probably diabase as opposed to porphyry. 6. Share. Report Save. Continue this thread level 2 · 4y. I ...

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  • Mafic

    Basalt: Fine grained and porphyritic: Porphyritic basalt: Pyroclastic: Basalt tuff or breccia: Vesicular: Vesicular basalt: Amygdaloidal: Amygdaloidal basalt: Many small vesicles: Scoria: Glassy: Tachylyte, sideromelane, palagonite: Related pages. List of minerals; Granite This page was last changed on 12 January 2018, at 06:56. Text is available under the Creative Commons Attribution/Share ...

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  • Basalt Fiber Reinforced Concrete

    Basalt has a . finegrained. mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow, although itoften is porphyritic, containing the larger crystals formed prior to the extrusion that brought the lava to the surface, embedded in a finergrained matrix. Figure . : ...

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  • KAr ages of late Cenozoic basalts from the western Snake ...

    Finegrained, porphyritic basalt contains glomeroporphyritic clumps of plagioclase (up to 2 mm long) and olivine. Interstitial material are composed of plagio clase, titanoaugite, olivine and oxide mesostasis. Analytical data: K = %; '^°Ar* = x 10"^^ moles/g; '^°Ar* = %. (whole rock) ± Ma 13 79H8 KAr Emmigrant Basalt, same as 79H85 (above). lytical data: K = ...

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  • basalt fine porphyritic

    Lunar sample 70215 is a dense, finegrained porphyritic mare basalt that has been used to create "touchstones" for public display (see list under Processing). It was collected about 60 m from the Lunar Module and is one of the largest stones returned from the Moon. Neal and Taylor (1993) alogued 70215 as a "high basaltporphyry Uni Salzburg. Porphyry is an igneous, .

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  • Porphyritic Basalt KOMATIITE resembles basalt but has 1 10 ...

    Porphyritic basalt komatiite resembles basalt but has. Porphyritic Basalt KOMATIITE (resembles basalt but has 1 ‐ 10 cm long criss ‐ crossing needles of olivine or pyroxene) Extrusive Aphanitic: fine ‐ grained RHYOLITE ANDESITE BASALT Glassy OBSIDIAN Vesicular PUMICE (abundant, tiny vesicles ‐ like meringue; very lightweight; white or ...

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  • Paul T. Robinson, Department of Earth Sciences, University ...

    the basalt consists of greenishgray, altered breccia, which grades downward into dark gray, finegrained basalt at about 25 meters below the sedimentbasalt contact. Because of the brecciated and altered nature of the basalt and the lack of an intrusive contact, this sequence is believed to represent oceanic basement of Upper Jurassic age.

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  • Weathering of basalt: geotechnical geochemical aspects

    Petrographic studies show that fresh basalt is holocrystalline to hypocrystalline, fine grained, porphyritic with phenocrysts of olivine, titanaugite, plagioclase and rare titanomagnetite set in a groundmass composed of plagioclase laths, titanaugite, olivine, glass and titanomagnetite; approximately olivine 33%, titanaugite 28%, plagioclase 34%, glass 2% and titanomagnetite .

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  • Lecture notes 3 Igneous Rocks

    Porphyritic (pr. Pore‐feritik) ‐ Larger crystals (phenocrysts [pr. Feen‐o‐krysts) in a "matrix" of smaller crystals. ... Gabbro – Basalt (Mafic) Gabbro‐ a mafic intrusive rock Basalt‐ a mafic extrusive rock • Key minerals‐ a few olivines, dominant pyroxene, dominant Ca‐rich plagioclase feldspars • Color‐ Dark ‐in plutonic rocks an more dark crystals than light ...

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  • IgnRx Study Guide

    Porphyritic rocks exhibit grains (crystals) in two, or more, sizes (or populations). The larger sized crystals are called phenocrysts. Phenocrysts are always large enough to be seen by the eye without magnifiion. By definition, phenocrysts are phaneritic. The smaller sized crystals between the larger sized crystals constitute the groundmass. Crystals of the groundmass may be visible to the ...

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  • basalt fine porphyritic

    Lunar sample 70215 is a dense, finegrained porphyritic mare basalt that has been used to create "touchstones" for public display (see list under Processing). It was collected about 60 m from the Lunar Module and is one of the largest stones returned from the Moon. Neal and Taylor (1993) alogued 70215 as a "high basaltporphyry Uni Salzburg. Porphyry is an igneous, volcanic rock composed ...

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  • by Terrence J. Boerboom John C. Green

    Silver Bay porphyritic basalt (Miller, 1988, 2002). nwp Weakly porphyritic ophitic basalt—Brown where weathered to dark grayishbrown where fresh, finegrained. Contains sparse dark gray to green, blockytabular plagioclase phenocrysts ranging from to centimeter in length. The size ). U 15 65 5 2

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  • IGNEOUS ROCKS Introduction textures ...

    have finegrained textures, including porphyritic, glassy, and frothy. In addition to texture, the mineral composition also determines the appropriate classifiion of an igneous rock. Determining composition of an igneous rock is not always easy, particularly because as the texture gets finer, the individual mineral grains become too small to be seen easily. In these cases, the color of a ...

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  • INTRODUCTION LITHOLOGY OF LEG 29 BASALTS

    porphyritic finegrained basalts toward the base of the core. The basalts of Core 13, Section 1, and Core 13, Section 2 are in lithic continuity with the vesicular basalts of Core 12, Section 1, but differ from them in their slightly coarser grain size and lack of vesicles and phenocrysts. The nonvesicular basalts are subfriable, and during drilling many of the short core segments were .

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  • Basalt Textures

    Basalt has several textural varieties such as glassy, massive, porphyritic, vesicular, scoriaceous. In the Keweenaw we can subdivide textures into three types, following Huber's example: Porphyrite, Trap and Ophite, applies ideally to Isle Royale, but works for the PLV on the Keweenaw too. Porphyrite or porphyritic basalt is characterized by obvious crystals, usually of plagioclase, which is ...

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