from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Any of a group of crystalline silicate minerals common in igneous and metamorphic rocks and containing two metallic oxides, as of magnesium, iron, calcium, sodium, or aluminum.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any of a group of crystalline minerals containing silicates of iron, magnesium and calcium.
from the GNU version of the Collaborative International Dictionary of English
- n. A common mineral occurring in monoclinic crystals, with a prismatic angle of nearly 90°, and also in massive forms which are often laminated. It varies in color from white to dark green and black, and includes many varieties differing in color and composition, as diopside, malacolite, salite, coccolite, augite, etc. They are all silicates of lime and magnesia with sometimes alumina and iron. Pyroxene is an essential constituent of many rocks, especially basic igneous rocks, as basalt, gabbro, etc.
from The Century Dictionary and Cyclopedia
- n. An important mineral species, embracing many varieties differing in appearance and chemical composition.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. any of a group of crystalline silicate mineral common in igneous and metamorphic rocks
The presence in the meteorites of micrometer-sized crystals of a mineral called pyroxene indicates that these rocks formed at a relatively shallow depth, between 15 and 20 meters, says Day - additional evidence that the meteorites are fragments of an ancient asteroid crust.
The prevalence of dark minerals such as pyroxene and olivine cause basalt to have a dark gray to black color.
"Typically, dust debris around other stars, or our own Sun, is of the olivine, pyroxene, or silica variety, minerals commonly found on Earth," said Dr. Carl Melis, who led the research as a graduate student at UCLA.
Most significant is the presence of the Sinharaja Basic Zone, consisting of hornblende, pyriclasts, basic charnokites, pyroxene amphibolites and scapolite-bearing calc-granulites and blended with small amounts of quartzites, garnet-biotite gneisses and intermediate charnokites.
Most chondrules are 0.5 to 2 millimeters in size and are composed of olivine and pyroxene, with smaller amounts of glass and iron-nickle metal.
Moondust is also rich in iron, calcium and magnesium bound up in minerals such as olivine and pyroxene.
Mafic igneous rocks tend to be dark in color because they contain a large proportion of minerals rich in iron and magnesium (pyroxene, amphiboles, and olivine).
These rocks are composed predominantly of the minerals plagioclase feldspar, amphibole, and pyroxene.
This region of the Earth's interior is thought to be composed of peridotite, an ultramafic rock made up of the minerals olivine and pyroxene.
Mostly the rocks brought back from the Sea of Tranquility were basalt: a dense, dark-gray, fine-grained igneous rock composed chiefly of calcium-rich plagioclase feldspar and pyroxene; on Earth, basalt is the commonest type of solidified lava.