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 (meaning without chondrules).
• Aerolite – an old term for stony meteorites.
• ALH – an abbreviation used for meteorites from Allan Hills.
• Allan Hills – a mountain chain in Antarctica where meteorites are concentrated by ice movements and can be easily spotted in the snow.
• 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.
• Anomalous – meteorites that have properties that are unusual for their group or grouplet.
• ANSMET – the ANtarctic Search for METeorites is scientific program that looks for meteorites in the Transantarctic Mountains.
• Asteroidal achondrite – an achondrite that differentiated on an asteroid or planetesimal (see planetary achondrite)
• 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 (HED meteorites + Angrite)
• Brachinite – either a primitive achondrite or an asteroidal achondrite

C

• C – can refer to carbonaceous chondrite or to an iron meteorite designation (Roman numeral and letter).
• Carbonaceous chondrite
• CAI – an abbreviation of Calcium-aluminium-rich inclusion
• Calcium-aluminium-rich inclusion
• Chassignite
• Chondrite – stony meteorites unmodified by melting or differentiation of the parent body
• Chondrule – millimetre-scale round grains found in chondrites
• Clan – 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.^[1]
• Class – two or more groups that have a similar chemistry and oxygen isotope ratios.^[1]
• Compositional type – a classification based on overall composition, for example stony, iron, stony-iron (as introduced by Maskelyne). 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 (See Micrometeorite).
• Cosmochemistry – the science of the chemistry of the Solar System, which is based in part on the chemistry of meteorites.

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. (See: achondrite)
• Differentiation – usually the process of a planetesimal forming an iron core and silicate mantle.
• Duo – a grouping of two meteorites that share similar characteristics (see Grouplet).

E

• E – can refer to enstatite chondrite or to an iron meteorite designation (Roman numeral and letter).
• Eagle Station grouplet – a set of pallasite meteorite specimen that don't fit into any of the defined pallasite groups.
• Electrophonic bolide – a meteoroid which produces a measurable discharge of electromagnetic energy (EMP) 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.^[2]:320 (It is, however, not a fossil).
• Fragment – a part of a meteorite that broke during passage through the atmosphere.
• Fragmentation – the process in which a meteorite breaks while falling through the atmosphere.
• Fusion crust – a coating on meteorites that forms during their passage through the atmosphere.

G

• Group – a collection of more than 5 meteorites sharing similar characteristics.^[1]
• Grouplet – a collection of less than 5 meteorites sharing similar characteristics.^[1]

H

• 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 content
• Hunter – a person who searches for meteorites.

I

• Impact breccia – rock composed of fragments of terrestrial, extraterrestrial or mixed origin fused by the energy of impact
• Impactite – informal term for a terrestrial rock resulting from the shocking impact of a meteor.
• 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 (mineral) found in meteorites.

L

• Lodranite – member of a small group of primitive achondrites thought to derive from deeper within the same parent body as acapulcoites
• Lunaite – a meteorite that originated from the moon (synonym of Lunar meteorite). Compare Category:Meteorites found on bodies other than Earth.
• Lunar meteorite – a meteorite that originated from the Moon (synonym of Lunaite). 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 – igneous, that is, solidified magma or produced by magma
• Magmatic meteorite
• Magnetic – a characteristic of a meteorite that is attracted to a magnet.
• Martian meteorite – a meteorite that originated from Mars. Compare Category:Meteorites found on bodies other than Earth.
• Maskelynite – a natural glas found in meteorites.
• Matrix – the mineral assemblage surrounding chondrules.
• Mesosiderite – a grouping of stony-iron meteorite that are breccias.
• Meteor – an object passing through Earth's atmosphere emitting light.
• Meteoric iron – a native metal found in meteorites and a mixture of different mineral phases. Compare telluric iron.
• Meteoroid – a natural object in space no larger than 1 meter.
• Meteorite – a rock found on the Earth's surface that did not form on Earth.
• Meteorite Observation and Recovery Program – a scientific program that was centered in Canada.
• Meteoriticist – a scientist working on meteorites.
• Meteoritics – the science of meteorites.
• MORP – abbreviation for Meteorite Observation and Recovery Program.
• Micrometeorite – microscopic meteorites derived from Cosmic dust.

N

• Nakhlite – a group of Martian meteorites
• Neumann lines (or Neumann bands) – a pattern of fine parallel lines seen in some iron meteorites, thought to be due to impact events on the parent body
• Nonmagmatic meteorite – (deprecated) iron meteorites that were thought to have not formed by igneous processes.
• Northwest Africa – a popular meteorite find location.
• NWA – abbreviation of northwest Africa.

O

• O – usually refers to ordinary chondrite
• Observed 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
• Oriented – e.g. Photo: An oriented specimen of the <name> meteorite.

P

• PAC – abbreviation for primitive achondrite.
• Pallasite
• Panspermia – the hypothesis that life could reach other planets by the means of meteorites and/or comets.
• Parent body
• Petrologic type
• 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 (See asteroidal achondrite).^[3]
• Plessite – a fine grained intergrowth found in meteoric iron consisting of kamacite, taenite and tetrataenite lamella.^[4]
• Presolar grains
• Primitive meteorite
• Primitive achondrite – a meteorite that has similarities with achondrites and chondrites.
• Pristine – extent of a meteorite shock stage and weathering.
• Protoplanetary disk – a cicumstellar disk from which all solids in the Solar System formed.
• Pyroxene pallasite grouplet

Q

• QUE – abbreviation for Queen Alexandra Range.
• Queen Alexandra Range – a mountain range in eastern Antarctica where many meteorites are found.

R

Regmaglypts on Sikhote Alin

• Regmaglypts – thumb print 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.^[5]
• Refractory elements – chemical elements that have high boiling and condensation temperatures.
• Rose-Tschermak-Brezina classification – a classification developed by Gustav Rose, Gustav Tschermak and Aristides Brezina.
• Rumuruti chondrite – a group of chondrites.

S

• Shergottite
• Shock stage
• Shock metamorphism
• Siderite – the old term for iron meteorite.
• Siderolite – the old term for stony-iron meteorites.
• SNC – abbreviation for shergottite, nakhlite and chassignite, the three martian meteorites.
• Solar nebula – a synonym of the protoplanetary disk.
• 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.

T

• Taenite – a native metal (mineral) found in meteorites.
• Tamdakht
• Tektite - glassy terrestrial debris created by meteorite impacts.
• Total known weight (TKW) – total known mass of a meteorite.
• Trio – a grouping of three meteorites that share similar characteristics (see Grouplet).
• Tunguska event – an air burst of a meteorite that caused major destruction.
• Type – subdivision of meteorites. Loosely defined. Usually refers to chondrite, achondrite and sometimes primitive achondrite.^[1]

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
• Ureilite

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

• Weathering – the terrestrial alteration of a meteorite.
• Widmanstätten pattern – a fine interleaving of kamacite and taenite bands/ribbons found in octahedrite irons and some pallasites.
• Winonaite
• Weston meteorite – The Weston meteorite is a meteorite which fell to earth above the town of Weston, Connecticut on December 14, 1807.^[6]

Y

• YA – abbreviation for Yamato Mountains.
• Yamato Mountains – a group of mountains in Antarctica where many meteorites are found.

References