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Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these ...
Trachybasalt – Volcanic rock – A volcanic rock with a composition between basalt and trachyte Hawaiite – Volcanic rock – a sodic type of trachybasalt, typically formed by ocean island volcanism; Trachyte – Extrusive igneous rock – A silica-undersaturated volcanic rock; essentially a feldspathoid-bearing rhyolite
Shield volcanoes are large, slow forming volcanoes [6] that erupt fluid basaltic magma that cools to form the extrusive rock basalt. Basalt is composed of minerals readily available in the planet's crust, including feldspars and pyroxenes. [2] Fissure volcanoes pour out low viscosity basaltic magma from fissure vents to form the extrusive rock ...
Igneous rocks are divided into two main categories: Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earth's crust. A common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, forming minerals such as pumice or basalt. [5]
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. [1] [2] Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, tuffaceous sandstone). [3]
The volcanic rock resulting from subsequent cooling is often also called lava. A lava flow is an outpouring of lava during an effusive eruption . (An explosive eruption , by contrast, produces a mixture of volcanic ash and other fragments called tephra , not lava flows.)
The word volcanic rock is derived from the Latin root words of Vulcan, [47] the Roman god of fire, and -ic, [48] meaning having some characteristics of. The word plutonic rock, another name for intrusive igneous rock, is derived from the Latin root words of Pluto, [49] the Roman god of the underworld, and -ic, [50] meaning having some ...
Another Hawaiian volcanic feature is the formation of active lava lakes, self-maintaining pools of raw lava with a thin crust of semi-cooled rock. [4] Ropey pahoehoe lava from Kilauea, Hawaiʻi. Flows from Hawaiian eruptions are basaltic, and can be divided into two types by their structural characteristics.