dacite
/ˈdeɪsʌɪt
/noun [mass noun] Geology
A volcanic rock resembling andesite but containing free quartz.The volcanic strata consist of sheet-like flows of andesite, dacite, basalts, and trachybasalts that are interbedded with agglomerates and tuffs....
- The belt comprises subalkaline andesites, trachyandesites, dacites, rhyolites, trachyrhyolites, and granodiorites, granites, granosyenites and monzonites, and developed along an active continental margin.
- Unchallengeable examples of what are assumed to have been beta quartz appear to be limited to occurrences in silicic volcanic rocks, such as rhyolite, liparite, and dacite.
Derivatives
dacitic
- The sulfur at El Desierto occurs in a whitish to grayish Pliocene tuff, consisting mostly of hardened, chiefly andesitic to dacitic, volcanic ashes, and capped by basalt.
- Previous work also has documented the presence of two distinct magma compositions beneath Nevado del Ruiz, one andesitic and the other dacitic, with mixing and mingling between the two during the November 1985 eruption.
- The injection of a mafic magma into a more silicic magma chamber is an important trigger mechanism in moderate-sized andesitic, dacitic and rhyolitic eruptions.
Origin
Late 18th century: from the name of the Roman province of Dacia (as it was first found in the Carpathian Mountains) + -ite1.
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