andesite

American  

[an-duh-zahyt] / ˈæn dəˌzaɪt /

noun

1. a dark-colored volcanic rock composed essentially of plagioclase feldspar and one or more mafic minerals, as hornblende or biotite.

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andesite British  

/ ˈændɪˌzaɪt /

noun

1. a fine-grained tan or grey volcanic rock consisting of plagioclase feldspar, esp andesine, amphibole, and pyroxene

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andesite Scientific  

/ ăn′dĭ-zīt′ /

1. A gray, fine-grained volcanic rock. Andesite consists mainly of sodium-rich plagioclase feldspar and one or more mafic minerals such as biotite, hornblende, or pyroxene. It often contains small, visible crystals (phenocrysts) of plagioclase.

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Other Word Forms

• andesitic
  adjective

Etymology

Origin of andesite

1840–50; named after Andes; see -ite ¹

Example Sentences

See Examples For:

andesite

Basalt, andesite, and granite can contain as much as 75 percent silicon dioxide.

From Science Daily ● Sep. 12, 2026

Test yourself on differentiating granite from andesite at the outdoor rock garden, meditate among CWU’s compact Japanese Garden, and watch for massive sculptures adorning CWU’s pathways.

From Seattle Times ● Feb. 23, 2022

Eichelberger, J. C. Origin of andesite and dacite: evidence of mixing at Glass Mountain in California and at other circum-Pacific volcanoes.

From Nature ● Dec. 12, 2017

In many places, the flowing water has worn those rocks smooth, showing how strong they are, and how seamlessly the andesite merges with the granitic rock.

From Scientific American ● Jun. 4, 2017

On the summits nearer to Tahoe the volcanic outflows were of andesite, a rough and porous rock of dark gray to dark brown color.

From The Lake of the Sky Lake Tahoe in the High Sierras of California and Nevada, its History, Indians, Discovery by Frémont, Legendary Lore, Various Namings, Physical Characteristics, Glacial Phenomena, Geology, Single Outlet, Automobile Routes, Historic Towns, Early Mining Excitements, Steamer Ride, Mineral Springs, Mountain and Lake Resorts, Trail and Camping Out Trips, Summer Residences, Fishing, Hunting, Flowers, Birds, Animals, Trees, and Chaparral, with a Full Account of the Tahoe National Forest, the Public Use of the Water of Lake Tahoe and Much Other Interesting Matter by George Wharton James