- a dark-colored volcanic rock composed essentially of plagioclase feldspar and one or more mafic minerals, as hornblende or biotite.
Origin of andesite
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Examples from the Web for andesitic
These are characterized by igneous rocks of andesitic nature.The Avifauna of Micronesia, Volume 3
Rollin H. Baker
The building fronts the west, and is constructed of an andesitic tuff of inferior quality and dark colour.
Great masses of granite, syenite and diorite were intruded at this period, and send tongues even into the andesitic tuffs.
It is composed of andesitic lavas of the augite type, is pierced by many fumaroles, and has a crater in the solfatara stage.
Amongst them I may mention those of Bougainville Strait, which are composed of andesitic lavas of the hornblende type.
- a fine-grained tan or grey volcanic rock consisting of plagioclase feldspar, esp andesine, amphibole, and pyroxene
C19: from Andes + -ite 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
- 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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