from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A usually coarse-grained igneous rock composed chiefly of calcic plagioclase and pyroxene. Also called norite.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A name originally given to a kind of serpentine, and now generally used for a coarsely crystalline, igneous rock consisting of lamellar pyroxene and labradorite.
from the GNU version of the Collaborative International Dictionary of English
- n. A name originally given by the Italians to a kind of serpentine, later to the rock called euphotide, and now generally used for a coarsely crystalline, igneous rock consisting of lamellar pyroxene (diallage) and labradorite, with sometimes chrysolite (olivine gabbro).
from The Century Dictionary and Cyclopedia
- n. A rock of varied lithological character, essentially, according to the present general acceptation of the name among lithologists, a crystalline-granular aggregate of plagioclase and diallage, with which often occur magnetite (or menachanite) and apatite.
- n. It is proposed, in the field classification of igneous rocks in connection with the quantitative system of classification (1902), to use the term gabbro for all granular igneous rocks with dominant pyroxene and subordinate feldspar of any kind, with or without hornblende and mica. Such rocks would include the less feldspathic gabbros and norites, and some diorites. See rock.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. one of a family of granular intrusive rocks
As to the speed of cutting, in the experiment quoted a bit of rather friable "gabbro," measuring three-quarters of an inch on the face by five-eighths of an inch thick, was cut clean through in six minutes, or by 3000 turns of the wheel.
To illustrate the operations, I will describe a specific case, viz. that of grinding the section of "gabbro"'above described, for microscopical purposes.
Like labradorite and anorthite, it is a common constituent of basic igneous rocks, such as gabbro and basalt.
Igneous rocks, including granite and gabbro, are common.
Some areas within this region have more alkaline soils, such as the Iredell series, formed over diabase, diorite, or gabbro, and may be associated with areas once known as blackjack oak prairies.
Mount Warning itself represents the original neck of the volcano which, being more resistant (comprising syenite, gabbro and monzonite) than the surrounding basalt and rhyolite, remains as an isolated plug.
Besides the dyke swarms, the northern section is composed mainly of serpentinised peridotite and gabbro masses, although there are small areas of extrusive volcanic rocks.
Dark-colored serpentine and gabbro also are found interstratified within the shales.
The higher elevations of the Nicobars often contain serpentine and gabbro formations, whereas at lower elevations Eocene sediments (sandstones, shales, and siltstones) with ultrabasic igneous intrusions predominate.
In the southwest the underlying bedrock is granite and gneiss, in the north and east there are magmatic rocks including reddish rapakivi granite, gabbro and anorthosite.