An extrusive igneous rock that develops from a magma that is chemically between felsic and mafic and whose mineral crystals are fine.

A fine-grained volcanic rock of intermediate composition, consisting largely of plagioclase and one or more mafic minerals.

dark-colored volcanic rock.

Igneous volcanic rock, less mafic than basalt, but more mafic than dacite; rough volcanic equivalent of diorite.

A type of rock that contains moderate amounts of silica and iron. Includes rocks such as scoria. Associated with cone volcanoes or stratovolcanoes. Mt Taranaki and Mt Tongariro are examples of andesite volcanoes.

[noun] An extrusive igneous rock of intermediate composition, often gray in color. The main minerals present in andesite are plagioclase and hornblende. The word "andesite" comes from the Andes Mountains in South America, where this rock type is common. Around the world, andesitic magma erupts out of volcanoes along convergent boundaries, [..]

(n) a dark grey volcanic rock

A fine grained intermediate volcanic igneous rock characterised by the presence of oligoclase or andesine. Their chemistry and mineralogy are closely similar to those of the diorites. Porphyritic vari [..]

Fine-grained, generally dark colored, igneous

Fine-grained, generally dark colored, igneous volcanic rock with more silica than basalt. Commonly with visible crystals of plagioclase feldspar. Generally occurs in lava flows, but also as dikes. The most common rock in volcanic arcs.

A fine-grained igneous rock in the diorite family that is intermediate in color between the light end of the spectrum (rhyolite) and the dark end of the spectrum (basalt).

Dark-colored, fine-grained extrusive igneous rock with about 52 to 63 weight percent silica (SiO2). Andesite consists mainly of plagioclase and one or more mafic minerals. The word andesite is derived [..]

A volcanic rock composed essentially of the mineral andesine and one or more of the mafic minerals.

A dark-colored, fine-grained extrusive rock that, when porphyritic, contains phenocrysts composed primarily of zoned sodic plagioclase (esp. andesine) and one or more of the mafic minerals (e.g., biotite, hornblende, pyroxene), with a groundmass composed generally of the same minerals as the phenocrysts, although the plagioclase may be more sodic, [..]

<chemical> An eruptive rock allied to trachyte, consisting essentially of a triclinic feldspar, with pyroxene, hornblende, or hypersthene. (01 Mar 1998)

Volcanic igneous rock related to granite.

(geology) A class of fine-grained intermediate igneous rock, of volcanic origin, containing mostly plagioclase feldspar.