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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