Glossary of meteoritics


This is a glossary of terms used in meteoritics, the science of meteorites.

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2 Pallas – an asteroid from the asteroid belt and one of the likely parent bodies of the CR meteorites.4 Vesta – second-largest asteroid in the asteroid belt and likely source of the HED meteorites.221 Eos – an asteroid from the asteroid belt and one of the likely parent bodies of the CO meteorites.289 Nenetta – an asteroid from the asteroid belt and one of the likely parent bodies of the angrites.3103 Eger – an asteroid from the asteroid belt and one of the likely parent bodies of the aubrites.3819 Robinson – an asteroid from the asteroid belt and one of the likely parent bodies of the angrites.IA meteorite – an iron meteorite group now part of the IAB group/complex.IAB meteorite – an iron meteorite and primitive achondrite of the IAB group/complex.IB meteorite – an iron meteorite group now part of the IAB group/complex.IC meteorite – an iron meteorite that is part of the IC group.

A

Ablation – the process of a meteorite losing mass during the passage through the atmosphere.Acapulcoite – a group of primitive achondrites.Accretion – the process in which matter of the protoplanetary disk coalesces to form planetesimals.Achondrite – a differentiated meteorite.Aerolite – an old term for stony meteorites.ALH – an abbreviation used for meteorites from Allan Hills.Allan Hills 84001 – is an exotic meteorite from Mars that does not fit into any of the SNC groups and was thought to contain evidence for life on Mars.Allende meteorite – is the largest carbonaceous chondrite ever found on Earth.Amphoterite – an obsolete classification of chondritic meteorites that are now classified as LL.Angrite – a basaltic meteorite.ANSMET – the Antarctic Search for Meteorites is a scientific program that looks for meteorites in the Transantarctic Mountains.Asteroidal achondrite – an achondrite that differentiated on an asteroid or planetesimal Asteroid spectral types – classification of asteroids according to their spectra.Ataxite – an iron meteorite that has no visible structures when etched.

B

Basaltic achondrite – a grouping of basalt meteorites Brachinite – either a primitive achondrite or an asteroidal achondriteBolide – is an extremely bright meteor, especially one that explodes in the atmosphere

C

C – can refer to carbonaceous chondrite or to an iron meteorite designation.Carbonaceous chondriteCAI – an abbreviation of calcium–aluminium-rich inclusionCalcium–aluminium-rich inclusionChassigniteChondrite – stony meteorites unmodified by melting or differentiation of the parent bodyChondrule – millimetre-scale round grains found in chondritesClan – meteorites that are not similar enough to form a group, but are also not too different from each other to be put in separate classes.Class – two or more groups that have a similar chemistry and oxygen isotope ratios.Compositional type – a classification based on overall composition, for example stony, iron, stony-iron. Can also refer to the composition deduced from spectroscopy of asteroids.Condensation – the process of chemicals changing from the gaseous to the solid phase during the cooling of the protoplanetary disk.Condensation sequence – the sequence of minerals that changes from the gaseous to the solid state while the protoplanetary disk cools.Cosmic dust – small interplanetary and interstellar particles that are similar to meteorites.Cosmochemistry – the study of the chemical composition of the universe and its constituents, and the processes that produced those compositions.

D

Dar al Gani – a meteorite field in the Libyan Sahara.Desert glass – natural glass found in deserts formed from the silica in sand as a result of lightning strikes or meteor impacts.Differentiated – a meteorite that has undergone igneous differentiation. Differentiation – usually the process of a planetesimal forming an iron core and silicate mantle.Duo – a grouping of two meteorites that share similar characteristics.

E

E – can refer to enstatite chondrite or to an iron meteorite designation.Eagle Station grouplet – a set of pallasite meteorite specimen that do not fit into any of the defined pallasite groups.Electrophonic bolide – a meteoroid which produces a measurable discharge of electromagnetic energy during its passage through the atmosphere.Enstatite achondrite – a meteorite that is mostly composed of enstatite. Usually part of the aubrite group.Enstatite chondrite – a rare form of meteorite thought to comprise only 2% of chondrites.

F

Fall – a meteorite that was seen while it fell to Earth and found.Find – a meteorite that was found without seeing it fall.Fossil meteorite – a meteorite that was buried under layers of sediment before the start of the Quaternary period. Some or all of the original cosmic material has been replaced by diagenetic minerals..Fusion crust – a coating on meteorites that forms during their passage through the atmosphere.

G

Group – a collection of five or more meteorites sharing similar characteristics.Grouplet – a collection of fewer than five meteorites sharing similar characteristics.

H

Hammer Stone – a specific individual meteorite that has hit either a human, man-made object, and/or an animal.HED – abbreviation for three basaltic achondrite groups howardite, eucrite and diogenite.HED meteorite – a clan of basaltic achondrites.Hexahedrite – a structural class of iron meteorites having a relatively low nickel contentHunter – a person who searches for meteorites.

I

Impact breccia – rock composed of fragments of terrestrial, extraterrestrial or mixed origin fused by the energy of impactImpactite – informal term for a terrestrial rock resulting from the shocking impact of a meteor.Insoluble organic matter – Kerogen-like macromolecule residue from carbonaceous chondrite meteorites after soluble organic matter has been removed.Iron–nickel alloy – an alternative expression for meteoric iron.Iron meteorite – a meteorite that is mainly composed of meteoric iron.

K

Kakangari chondrite – a group of chondrite meteorites.Kamacite – a native metal found in meteorites.

L

Lodranite – member of a small group of primitive achondrites thought to derive from deeper within the same parent body as acapulcoitesLunaite – a meteorite that originated from the Moon. Compare :Category:Meteorites found on bodies other than Earth.Lunar meteorite – a meteorite that originated from the Moon. Compare :Category:Meteorites found on bodies other than Earth.

M

Main group pallasite – a pallasite belonging to the main group.Main mass – the largest/heaviest piece of a fragmented meteorite, typically found in a strewn field.Magmatic meteoriteMartian meteorite – a meteorite that originated from Mars. Compare :Category:Meteorites found on bodies other than Earth.Maskelynite – a natural glass found in meteorites.Matrix – the mineral assemblage surrounding chondrules.Mesosiderite – a grouping of stony-iron meteorite that are breccias.Meteoric iron – a native metal found in meteorites and a mixture of different mineral phases. Compare telluric iron.Meteorite Observation and Recovery Program – a scientific program that was centered in Canada.Meteoriticist – a scientist working on meteorites, meteors, and meteoroids.Meteoritics – the science of meteorites, meteors, and meteoroids.MORP – abbreviation for Meteorite Observation and Recovery Program.Micrometeorite – microscopic meteorites derived from Cosmic dust.

N

Nakhlite – a group of Martian meteoritesNeumann lines – a pattern of fine parallel lines seen in some iron meteorites, thought to be due to impact events on the parent bodyNonmagmatic meteorite – iron meteorites that were thought to have not formed by igneous processes.

O

O – usually refers to ordinary chondriteObserved fall – a meteorite that was seen when it fell to Earth.Octahedrite – the most common structural class of iron meteorites.Ordinary chondrite – a chondrite meteorite, where 'ordinary' means that it is the most common found

P

PAC – abbreviation for primitive achondrite.Pallasite – a class of stony–iron meteorite.Panspermia – the hypothesis that life could reach other planets by the means of meteorites and/or comets.Parent body – the celestial body from which originates a meteorite or a class of meteorites.Petrologic type – a classification scheme that expresses the degree to which a meteorite has been affected by the secondary processes of thermal metamorphism and aqueous alteration on the parent asteroid.Pitts grouplet – a grouplet of meteorites that is part of the IAB meteorites.Planetary achondrite – an achondrite that was differentiated on a planet and not a planetesimal or asteroid.Plessite – a fine grained intergrowth found in meteoric iron consisting of kamacite, taenite and tetrataenite lamella.Presolar grains – interstellar solid matter in the form of tiny solid grains from a time before the Sun was formed.Primitive meteoritePrimitive achondrite – a meteorite that has similarities to achondrites and chondrites.Protoplanetary disk – a circumstellar disk from which all solids in the Solar System formed.

R

Regmaglypts – thumbprint-sized indentations in the surface of larger meteorites formed by ablation as the meteorite passes through a planet's atmosphere, probably caused by vortices of hot gas.Rose-Tschermak-Brezina classification – a classification developed by Gustav Rose, Gustav Tschermak and Aristides Brezina.Rumuruti chondrite – a group of chondrites.

S

Shergottite – igneous rocks of mafic to ultramafic lithology, named after a meteorite that fell at Sherghati, India in 1865.Shock stage – a measure of the degree of fracturing of the matrix of a common chondrite meteorite.Shock metamorphism – the effects of shock-wave related deformation and heating during impact events. Siderite – the old term for iron meteorite.Siderolite – the old term for stony-iron meteorites.SNC – abbreviation for shergottite, nakhlite and chassignite, the three main types of Martian meteorite.Solar nebula – a synonym of the protoplanetary disk.Soluble organic matter – compounds that can be extracted from carbonaceous chondrites using water or other solvents. These compounds include amino acids, carboxylic acids, and nucleotide bases.Spectral class –Stony meteorite – a meteorite composed mostly of silicates.Stony-iron meteorite – a meteorite that is a mixture of meteoric iron and silicates.Strewn field – a field of fragments from one meteorite fall.Structural class – a subdivision of iron meteorites in ataxites, hexahedrites and octahedrites.Superbolide – is a bolide that reaches an apparent magnitude of −17 or brighter, which is roughly 100 times brighter than the full moon. Recent examples of superbolides include the Sutter's Mill meteorite and the Chelyabinsk meteor.

T

Taenite – a native metal found in meteorites.Tamdakht – a meteorite that fell near Ouarzazate, Morocco on 2008-12-20 producing a strewn field of approximately 25 km by 2 km and two small impact craters.Tektite – glassy terrestrial debris created by meteorite impacts.Thumbprinting – see regmaglypts Total known weight – total known mass of a meteorite.Trio – a grouping of three meteorites that share similar characteristics.Type – subdivision of meteorites. Loosely defined. Usually refers to chondrite, achondrite and sometimes primitive achondrite.

U

Udei Station grouplet – a grouplet of meteorites that is part of the IAB meteorites.Ungrouped – a meteorite that has not been assigned to a group or grouplet.Undifferentiated

V

Vesta – second largest asteroid in the asteroid belt and likely source of the HED meteorites.Volatile elements – are chemical elements that have low boiling and condensation temperatures.

W

Widmanstätten pattern – a fine interleaving of kamacite and taenite bands/ribbons found in octahedrite irons and some pallasites.Willamette meteorite – the largest meteorite discovered in North America, found in the Willamette Valley of Oregon.Winonaite – a type of primitive achondrite meteorite.Weston meteorite – a meteorite which fell to earth above the town of Weston, Connecticut on December 14, 1807.