- a dark-colored volcanic rock composed essentially of plagioclase feldspar and one or more mafic minerals, as hornblende or biotite.
Origin of andesite
Examples from the Web for andesite
Historical Examples of andesite
In the main the lava is an andesite, and is very generally of a porphyritic structure.Mount Rainier
The rocks of which the mountains are composed consist of varieties of andesite.Volcanoes: Past and Present
Surface eruption of quartz-porphyry, rhyolite, and andesite.
A later series of small diorite or andesite dikes cut the ore bodies.The Economic Aspect of Geology
C. K. Leith
The Ochils and other hills of middle Scotland largely consist of andesite.
- a fine-grained tan or grey volcanic rock consisting of plagioclase feldspar, esp andesine, amphibole, and pyroxene
Word Origin for andesite
- 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.