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The texture of extrusive rocks is characterized by fine-grained crystals indistinguishable to the human eye, described as aphantic. Crystals in aphantic rocks are small in size due to their rapid formation during eruption. [3] Any larger crystals visible to the human eye, called phenocrysts, form earlier while slowly cooling in the magma ...
Extrusive igneous rock, also known as volcanic rock, is formed by the cooling of molten magma on the earth's surface. The magma, which is brought to the surface through fissures or volcanic eruptions, rapidly solidifies. Hence such rocks are fine-grained or even glassy. Basalt is the most common extrusive igneous rock [9] and forms lava flows ...
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
In 1992, Coffin and Eldholm initially defined the term "large igneous province" as representing a variety of mafic igneous provinces with areal extent greater than 100,000 km 2 that represented "massive crustal emplacements of predominantly mafic (magnesium- and iron-rich) extrusive and intrusive rock, and originated via processes other than 'normal' seafloor spreading."
Quartzolite or silexite is an intrusive igneous rock, in which the mineral quartz is more than 90% of the rock's felsic mineral content, with feldspar at up to 10%. [ 1 ] : 135 [ 2 ] Typically, quartz forms more than 60% of the rock, [ 3 ] the rest being mostly feldspar although minor amounts of mica or amphibole may also be present. [ 2 ]
Trachyte (/ ˈ t r eɪ k aɪ t, ˈ t r æ k-/) is an extrusive igneous rock composed mostly of alkali feldspar.It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, [1] and is formed by the rapid cooling of lava (or shallow intrusions) enriched with silica and alkali metals.
Trap rock, also known as either trapp or trap, is any dark-colored, fine-grained, non-granitic intrusive or extrusive igneous rock. Types of trap rock include basalt, peridotite, diabase, and gabbro. [1] Trap is also used to refer to flood (plateau) basalts, such as the Deccan Traps and Siberian Traps. [2]
Water politics, sometimes called hydropolitics, is politics affected by the availability of water and water resources, a necessity for all life forms and human development. Arun P. Elhance's definition of hydropolitics is "the systematic study of conflict and cooperation between states over water resources that transcend international borders ...