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What is the characteristics of basalt?
Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. It has a composition similar to gabbro.
What are the characteristics of basaltic lava?
Basalt is a hard, black volcanic rock with less than about 52 weight percent silica (SiO2). Because of basalt’s low silica content, it has a low viscosity (resistance to flow). Therefore, basaltic lava can flow quickly and easily move >20 km from a vent.
What type of rock is most difficult to identify?
metamorphic rock
All rocks start out as igneous or sedimentary rocks – any and everything that can happen to those will make a metamorphic rock – so that category is the most diverse and difficult to identify.
Which is the best description of a basalt rock?
Basalt 1 Classification. Basalt has a strict chemical definition. It is defined in the TAS diagram shown above. 2 Types of Basalt. Tholeiitic basalt is relatively rich in silica and poor in sodium. 3 Petrology. The mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene.
Which is the most common type of igneous rock?
Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. Basalt underlies more of Earth’s surface than any other rock type.
What’s the difference between basalt and gabbro rock?
It has a composition similar to gabbro. The difference between basalt and gabbro is that basalt is a fine-grained rock while gabbro is a coarse-grained rock. Olympus Mons Volcano: This shield volcano is composed of basalt and has enormous calderas at the summit.
What are the colors of felsic igneous rocks?
Felsic igneous rocks, as a whole rock, tend to have light colors or shades: white, pink, light brown, light gray. Mafic igneous rocks, on the whole, tend to be dark colored, commonly black or dark gray. Most mafic magma originates by melting of rocks in the mantle that are extremely rich in iron and magnesium.