2024年1月31日 · Examples of extrusive igneous rocks include: Basalt : A dark, fine-grained rock, commonly found in oceanic crust. Andesite : Typically found in volcanic arcs associated with subduction zones.

When lava is extruded onto the surface, or intruded into shallow fissures near the surface and cools, the resulting igneous rock is called extrusive or volcanic. Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye.

Extrusive igneous rocks, also known as volcanic rocks, are formed when magma reaches the Earth's surface and cools rapidly. This process occurs when magma from the Earth's mantle rises to the surface through volcanic vents or fissures, resulting in volcanic eruptions.

Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. [1]

Intermediate Igneous rocks Examples: Andesite: A fine-grained volcanic rock, often found in volcanic arcs associated with subduction zones. Diorite: A coarse-grained intrusive rock with a speckled appearance due to the intermingling of light and dark minerals.

2023年12月12日 · Intermediate igneous rocks are medium in silica (52-63 wt.%) and have nearly equal amounts of felsic and mafic minerals. Examples are andesite and diorite. Felsic minerals are light-colored minerals like quartz, feldspars, muscovite, feldspathoids, and conundrums.

Mafic, felsic, and intermediate extrusive rocks. More general terms for these rocks are mafic, felsic, and intermediate. Mafic rocks have about 50 percent silica and high amounts of iron, magnesium, and calcium and are dark in color. A common mafic rock is basalt.

2018年4月13日 · Basalt is the most common extrusive rock while granite is a very common intrusive rock. Extrusive igneous rocks come from lava, forming at the surface of the Earth and cooling quickly, meaning they form very small crystals.

A rock of intermediate composition is diorite if it is course-grained, and andesite if it is fine-grained. A mafic rock is gabbro if it is course-grained, and basalt if fine-grained. The course-grained version of an ultramafic rock is peridotite , and the fine-grained version is komatiite .

2024年5月16日 · A felsic intrusive rock is called granite, whereas a felsic extrusive rock is called rhyolite. Granite and rhyolite have the same mineral composition, but their grain size gives each a distinct appearance. A rock of intermediate composition is diorite if it’s course-grained, and andesite if it’s fine-grained.