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A fine-grained light gray volcanic rock consisting primarily of quartz, plagioclase feldspar, and potassium feldspar, and also containing biotite, hornblende, or pyroxene.

[After Dacia.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


an igneous, volcanic rock characteristically light in colour with relatively high silica content
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.dacite - a grey volcanic rock containing plagioclase and quartz and other crystalline minerals
oligoclase, plagioclase - any of a series of triclinic feldspars that form rocks
volcanic rock - extrusive igneous rock solidified near or on the surface of the Earth
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References in periodicals archive ?
The felsic volcanic sequence consists of dacitic (to rhyolitic) composition intercalated lapilli tuffs, flow banded and fine grained dacites. This association has been interpreted to be part of a dacitic dome structure.
Table 2 represents the chemical compositions by energy dispersive spectroscopy (EDS) performed on some one hundred ash particles revealed on average typical geochemical ratios known of andesites and dacites of the region with Al/Mg of 9.85, Si/Mg of 24.97, and Na/Al ratios of about 0.29, with a sigma mean error between 0.26 and 0.97, pending of the particular element.
For this study, 20 thin sections of Zanbil dacites possessing phases and textures of interest for CSD studies were selected.
The collected rock samples lie in Volcanic Formation" which consists of dolerites, andesite, dacites, dacitic tuff, rhyolites and rhyolitic tuff.
On the basis of whole rock geochemistry the rocks of Deosai volcanics are classied as dacites to rhyodacite and the meta-volcanics of Burji-La Formation have basalt to basaltic-andesite composition.
Geologically, it includes predominantly Silurian limestone and marble outcrops intruded by Devonian acidic porphyry (dacites) and granites.
Also in this south sector (Cordon del Portillo) there is a plutonic association of gabbros and tonalites to granodiorites, and a volcanic sequence of andesites and dacites to rhyodacites and rhyolites (Polanski, 1972).
Eruptive products range from ignimbrites (calc-alkaline dacites), lava flows and tephras (tholeiitic basalts and basaltic andesites).
The Sabalan volcano (Ardabil) is among the youngest volcanic calderas, in eastern border of the Turkish-Iranian Plateau, consisting of Miocene trachyandesites and Plio-Quaternary trachy-andesite, pumiceous andesites, and dacites with ultrapotassic-shoshonitic signatures.
The rhyolites range from 0.71 to 0.74; dacites present values of 0.66 and and esites around 0.58.