from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A gray, fine-grained volcanic rock consisting chiefly of plagioclase feldspar and one or more mafic minerals.
from The Century Dictionary.
- noun A volcanic rock of wide-spread occurrence, especially in the Cordilleran region of North America.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Min.) An eruptive rock allied to trachyte, consisting essentially of a triclinic feldspar, with pyroxene, hornblende, or hypersthene.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun geology A class of fine-grained
intermediate igneous rock, of volcanicorigin, containing mostly plagioclase feldspar.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun a dark grey volcanic rock
from The American Heritage® Dictionary of the English Language, 4th Edition
A third type of magma, called andesite, named after the Andes Mountains where it is often found, is composed of a mixture of both felsic and mafic magma.
(FeCO3), used as a pigment, and also found in the Kirtland shale; and various metamorphic and igneous rocks (such as andesite, schist, gabbro, slate, and olivine), which could have been picked up in the river
The Miocene volcanic rocks are mostly andesite, basalt, and pyroclastic rocks.
St. Lucia, and Martinique are predominantly composed of acid andesite and dacitic rocks.
The western Cascades are older and more eroded than the lava plateau and prominent snow-covered cones of the high Cascades (Ecoregions 4c and 4d); they are composed of dark basalt in contrast to the gray andesite of the high Cascades.
Miocene basalt, andesite, pyroclastic, and marine sedimentary rocks predominate in this subsection.
Floral mapping of the nominated area recognizes 5 broad communities including the dolomite grasslands, andesite mountain bushveld, witwatersrand mountain bushveld, VD granite grassland and the riverine bushland.
The Volcanic Mid-Elevation Forests ecoregion occurs at elevations of about 7500 to 10,000 feet and is composed of igneous rocks of andesite and basalt.
Basalt magma typically generates very little ash compared to other types (andesite, dacite, and rhyolite).
Typically occurring in Virginia are basalt and metabasalt of the Catoctin Formation, granite and granodiorite of the Virginia Blue Ridge Complex, and andesite, tuft, and greenstone of the Swift Run Formation.