Andesite (/ ˈ æ n d ə z aɪ t /) [1] is a volcanic rock of intermediate composition.In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite.It is fine-grained to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.[2]Andesite is the extrusive equivalent of plutonic diorite.

What is Andesite? Andesite is the name of a family of fine-grained, extrusive igneous rocks that are usually light to dark gray in color. They have a mineral composition that is intermediate between granite and basalt.Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates.

2023年9月4日 · Andesite is an intermediate sub-alkalic rock with SiO2 contents ranging between 57 and 63 wt. %, and Na2O + K2O contents around 5 wt. %.Intermediate rocks are also characterized by an increased CaO content compared to that in acidic rocks. Similar CaO contents (6 – 7 wt. %) are also typical for diorite – the plutonic equivalent of andesite. The …

2023年7月3日 · Andesite is a fine-grained, intermediate volcanic or extrusive igneous rock. Its composition lies between basalt and dacite, and it has mainly sodium-rich plagioclase and one or more mafic minerals, especially pyroxenes or hornblende.. As McBirney (1989) narrates, Leopold Von Buch coined the term andesite in 1827 to describe porphyritic rocks with albite and …

Andesite is a fine-grained volcanic rock that forms through the rapid cooling of magma at or near the Earth's surface, typically in volcanic regions. It is an extrusive igneous rock, meaning it solidifies from molten lava expelled during volcanic eruptions. Andesite is named after the Andes Mountains in South America, where it is commonly found.

andesite, any member of a large family of rocks that occur in most of the world’s volcanic areas.Andesites occur mainly as surface deposits and, to a lesser extent, as dikes and small plugs. Many of the deposits are not normal lava flows but rather flow breccias, mudflows, tuffs, and other fragmental rocks; the peperino near Rome and the trass of the Eifel district in …

Andesite (/ˈændəzaɪt/) is a volcanic igneous rock with an intermediate composition. It is fine-grained (aphanitic) to porphyritic in texture, primarily composed of plagioclase feldspar (often andesine), along with pyroxene or hornblende. It is considered to be the extrusive counterpart of diorite, the plutonic equivalent.Andesite is common in island arcs and subduction zones, …

Andesite comes in many colors but is usually light or dark gray, and is often porphyritic. Andesite is intermediate in composition between basalt and rhyolite. While andesite is a clearly defined rock type, it can sometimes be hard to distinguish it from closely related rocks – especially if you don’t have access to sophisticated testing ...

Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent silica (SiO2). Andesites contain crystals composed primarily of plagioclase feldspar and one or more of the minerals pyroxene (clinopyroxene and orthopyroxene) and lesser amounts of hornblende. At the lower end of the silica range, andesite lava may also contain olivine.

Andesite lavas usually have porphyritic, or vitrophyric textures, and the phenocrysts often provide a remarkable record of at least part of the evolutionary history of the rocks. They color index (M) generally range from 20 to 40. Plagioclase and pyroxene are the normal essential minerals and plagioclase is the usually the most abundant phenocryst.