Glossary of meteoritics

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

#

• 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 and mesosiderites.
• 20 Massalia – likely source of the L type ordinary chondrites.
• 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 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 (see planetary achondrite)
• Asteroid spectral types – classification of asteroids according to their spectra.
• Ataxite – an iron meteorite that has no visible structures when etched.
• Aubrite – a class of achondrite meteorites composed primarily of the orthopyroxene enstatite

B

• Basalt – mafic igneous rock found on the terrestrial planets and differentiated asteroids, found in meteorites such as shergottites (Mars) and eucrites (Vesta).
• Basaltic achondrite – a grouping of basalt meteorites (HED meteorites + Angrite)
• Brachinite – either a primitive achondrite or an asteroidal achondrite
• Bolide – 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 (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.
• 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 (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 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. (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 do not 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.^: 320 (It is, however, not a fossil).
• 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 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.
• 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 (mineral) found in meteorites.

L

• Lherzolite – a variety of olivine rich ultramafic plutonic rock that contains both clino- and ortho- pyroxene. They are usually shergottites and also occur in Earth’s upper mantle.
• Lherzolitic shergottite – an olivine rich, plutonic shergottite that formed as a cumulate rock on Martian magma chambers.
• 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 meteorite - achondrites of magmatic origin and iron meteorites (includes pallasites).
• Martian 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.
• Missing mantle problem – planetary paradox where expected olivine rich silicate mantle debris from early differentiation and impacts is missing from the asteroid belt and meteorite record .

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.
• NWA – Northwest Africa, meteorite recovered somewhere in the Sahara or Sahel regions including Morocco, Algeria, Mali, Mauritania, Niger, or Libya without a precise, documented find site or GPS coordinates.

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

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.
• Peridotite – olivine rich plutonic igneous rocks native to mantles, found in certain Martian achondrites (chassignites and lherzolitic shergottites) and as ureilites and brachinites
• 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 (See asteroidal achondrite).
• 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 meteorite - chondrites and primitive achondrties such as winonaites, lodranites, and acapulcoites.
• Primitive achondrite – a meteorite that has similarities to achondrites and chondrites.
• Protoplanetary disk – a circumstellar disk from which all solids in the Solar System formed.
• Pyroxene pallasite grouplet
• Pyroxenite – pyroxene rich plutonic igneous rocks, found in certain Martian achondrites (nakhlites) and as diogenites

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 (mineral) found in meteorites.
• Tamdakht – a meteorite that fell near Ouarzazate, Morocco on 2008-12-20 producing a strewn field of approximately 25 km (16 mi) by 2 km (1.2 mi) and two small impact craters.
• Tektite – glassy terrestrial debris created by meteorite impacts.
• Thumbprinting – see regmaglypts
• Total known weight (TKW) – total known mass of a meteorite.
• Trio – a grouping of three meteorites that share similar characteristics (see Grouplet).
• 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
• 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

• 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.

References