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New England
Meteoritical Services
Glossary of
Meteoritical Terms
Chondrules, some of the most
primitive matter known.
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- ACHONDRITE
- (a kon' drite) - A stone meteorite that contains no
chondrules.
- ATAXITE
- (a tax' ite) - An iron meteorite made almost entirely
of taenite. The name means "without structure" and
refers to the lack of a visible Widmanstätten pattern.
- AUGITE
- (aw' gite) - A common mineral of the
pyroxene group with the complex formula,
Ca(Mg,Fe,Al)(Si,Al)2O6.
- BASALT
- (ba salt') - A volcanic
igneous rock made principally of pyroxene and plagioclase.
- BRECCIA
- (bret' chee a) - A rock consisting of broken fragments
of rock (clasts) cemented together by a fine-grained matrix. Formed from regolith during
subsequent impacts.
- CHONDRITE
- (kon' drite) - A relatively abundant type of stone
meteorite characterized by the presence of chondrules.
- CHONDRULES
- (kon' drools) - Millimeter-sized glass spheres found in
abundance in chondrite meteorites.
- DIFFERENTIATED
- (dif' e ren' shee ay ted) - In this context, a
planetary or asteroidal body that has separated into regions of different
composition, such as core, mantle and crust.
- ENSTATITE
- (en' ste tite) - A mineral of the pyroxene group of silicates
containing magnesium and no iron - MgSiO3. A class of
meteorite.
- EUCRITE
- (yoo' krite) - A type of achondrite meteorite made primarily from
basaltic plagioclase and
pyroxene.
- FELDSPAR
- (feld' spar) - A major rock building mineral containing
silicates of aluminum.
- FUSION CRUST
- (fyoo' zhen krust) - The melted glassy exterior of a
meteorite that forms during atmospheric passage. Primary crust is the material
that forms from the beginning of incandescent flight until dark flight.
Secondary crust forms when a piece breaks off the main mass during incandescent
flight and begins to form a new crust on the broken surfaces.
- GRAPHITE
- (graf' ite) - An opaque form of carbon found in some
iron, ordinary chondrite and ureilite meteorites.
- HEXAHEDRITE
- (hek sa hee' drite) - A type of iron meteorite made
entirely of kamacite and named for its cubic
(hexahedral) crystal structure.
- IGNEOUS
- (ig' nee us) - one of the three basic types of rock;
formed from the solidification of magma.
- INCLUSION
- (in kloo' zhun) - A body of foreign material enclosed
within the primary matrix of a meteorite.
- ISOTOPE
- (eye' sa tope) - One of two or more atoms with the same
atomic number, but different masses.
- KAMACITE
- (kam' a site) - A metal composed of a nickel-iron alloy
with up to 7.5 percent nickel.
- MAIN MASS
- The total preatmospheric mass of a meteoroid or the largest known fragment of a
meteorite.
- MATRIX
- (may' triks) - The fine grained primary material in a
meteorite that surrounds inclusions,
chondrules and clasts in breccia.
- METEOR
- (meet' ee or) - The flash and steak of light produced
by a meteoroid as it vaporizes in the atmosphere.
- METEORITE
- (meet' ee a rite) - Any meteoroid that has fallen to
the surface of the Earth.
- METEOROID
- - (meet' ee a royd) - Any rock or iron natural object
moving through interplanetary space that is smaller than an asteroid and larger
than a molecule.
- OCTAHEDRITE
- (ahk ta hee' drite) - An iron meteorite composed of
taenite and kamacite, named for
the octahedral (eight sided) shape of the kamacite crystal growth.
- OLIVINE
- (ahl' a veen) - A group of silicate minerals with a compositional range running from
all magnesium - forsterite, Mg2SiO4 - to all iron - fayalite,
Fe2SiO4 - common in pallasites, chondrites and some
achondrites.
- OLIVINE-BRONZITE
- (ahl' a veen - brahn' zite) - The name given to H class
ordinary chondrites as they are composed of olivine and
bronzite, a pyroxene with about 20%
FeSiO3.
- OLIVINE-HYPERSTHENE
- (ahl' a veen - hi' pers theen) - The name given to L
class ordinary chondrites as they are composed of olivine and hypersthene, a pyroxene
containing 22-30% FeSiO3.
- PETROLOGY
- (pe trahl' e jee) - A science dealing with the origin,
history, occurrence, chemical composition, structure and classification of
rocks.
- PLAGIOCLASE
- (play' jee oh clace) - A common rock-forming series of
feldspars consisting of mixtures of sodium and calcium
aluminum silicates.
- PLESSITE
- (ples' site) - A mineral composed of a fine-grained
mixture of kamacite and taenite
that fills in the wedges between kamacite and taenite bands in iron
meteorites.
- PLUTONIC
- (ploo tahn' ic) - Igneous rocks
that form from the cooling of magma in the interior of a planet or
asteroid.
- PYROXENE
- (pie roks' een) - A major group of silicate minerals of which two end members are enstatite
- MgSiO3 and ferrosilite - FeSiO3.
- REGMAGLYPTS
- (reg' mag lips) - Depressions resembling (and called)
thumbprints that are produced on the surface of some meteorites during
atmospheric transit by material ablating (melting) off the surface.
- REGOLITH
- (reg' oh lith) - A mixture of rocky fragments covering
the surface of an asteroid or planet, the product of "gardening" by repeated
meteorite impacts.
- SILICATES
- (sil' i kets) - Any of a large group of minerals that
contain silicon, oxygen and one or more metals.
- TAENITE
- (tay' nite) - A metal composed of a nickel-iron alloy
with a nickel content varying from about 27% to 65%.
- TEKTITE
- (tek' tite) - A form of natural glass that, in many
specimens, exhibit aerodynamic shaping caused by atmospheric passage while
molten. Origin in not known, but a possibility is that they represent drops of
molten silicates "splashed" out from meteorite impact
events.
- TROILITE
- (troy' lite) - The brass colored sulfide of iron (FeS)
common to many types of meteorites.
- VOLCANIC
- (vawl can' ic) - Igneous rock
that forms from the cooling of magma on the surface of a planet or
asteroid.
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