Acronyms and Terms

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Home Antarctic MeteoritesMartian Meteorite CompendiumAcronyms and Terms

The Martian Meteorite Compendium

Acronyms and Terms
(also see Dictionary of Geological Terms)

Achondrite
Stony meteorite, lacking chondrules. Igneous origin. Relatively rare.
ANSMET
Antarctic Search for Meteorites, funded by U. S. National Science Foundation; led by William Cassidy and Ralph Harvey.
AMN
Antarctic Meteorite Newsletter (issued by NASA-JSC, Astromaterials Curation Office).
ARES
Astromaterials Research and Exploration Science at the Johnson Space Center.
"Blue Ice"
Locations in Antarctica where samples were recovered (Map of Antarctic Meteorite Locations).
     ALH
Allan Hills Icefield.
     EET
Elephant Moraine.
     EET
Elephant Moraine.
     LAR
Larkman Nunatak.
     LEW
Lewis Cliffs Ice Field.
     MIL
Miller Range.
     QUE
Queen Alexander Range.
     RBT
Roberts Massif.
     YAMATO
Yamato Mountains.
     GRV
Grove Mountains.
BM (now NHM)
British Museum of Natural History, now The Natural History Museum, London.
Chassignite
Type of meteorite like Chassigny, which is an olivine-rich dunite, thought to be from Mars.
Cosmogenic Isotopes
Isotopes produced by interaction of high-energy cosmic rays with elements in sample.
DaG
Dar al Gani, Libya.
Deflation
Wind erosion area.
Dho
Dhofar, Oman.
Diabasic
Mafic subvolcanic rock type that is compositionally equivalent to basalt, and typically contains plagioclase feldspar, pyroxene, and olivine as the major minerals; also a class of the shergottite meteorites.
DML
Dark mottled lithology of Zagami meteorite.
DN
Olivine-rich lithology of Zagami, obtained from David New.
Druse
A crust or coating of small crystals in a crack or void (see Martinez and Gooding, 1986 for a description of "white-druse").
dpm
Disintegrations per minute.
Educational Thin Section Set
JSC, BM(NHM) and NIPR all have sets of thin sections of meteorites, with educational pamphlets, for use by educational institutions.
EMPA
Electron microprobe analysis.
Ejection age
The sum of the exposure age and terrestrial age, the time since the sample was ejected from Mars.
Exposure age
The time interval a small body (~1m) spends in space as measured by radionuclides generated by high energy cosmic rays.
Fusion crust
Thin glass coating found on outer surface of meteorite due to heating by atmospheric entry.
Gabbroic
Coarse-grained mafic intrusive rocks, compositionally equivalent to basalt, and consisting of olivine, pyroxene, and plagioclase feldspar as the major minerals; also a class of the shergottite meteorites.
HED
Howardite, Eucrite, Diogenite. Large group of apparently related achondrites.
g
gram (also kg = kilogram and mg = milligram etc.).
Ga
1,000,000,000 years.
GPa
Giga Pascals (unit of pressure).
IDMS
Isotope Dilution Mass Spectroscopy.
INAA
Instrumental Neutron Activation Analysis.
Isochron
A constant-time line on a diagram that compares ratios of radioactive isotopes to their stable daughter isotopes.
Interstitial
Area between the other major mineral phases.
JaH
Jiddat al Harasis, a dense meteorite collection area in Oman.
JSC
Lyndon B. Johnson Space Center, Houston, Texas 77058
Katabatic wind
The wind that blows off of the Antarctic continent.
lherzolite
Two pyroxene rock, plutonic.
Lithology A, B, and C
Three distinct lithologies in the meteorite EET 79001; lithology A is olivine-phyric, lithology B is diabasic, and lithology C is glassy melt pocket thought to have formed by impact on Mars.
Ma
1,000,000 years
Martian Meteorite
A meteorite from Mars; also previously called "SNC" meteorites — Shergottites–Nakhlites–Chassigny.
MER
Mars Exploration Rovers – Spirit and Opportunity.
MWG
Meteorite Working Group. U. S. advisory panel to ANSMET/NASA/Smithsonian.
Magmatic inclusion
Small recrystallized glass inclusions usually found in early-formed olivine or chromite crystals (presumably trapped magmatic liquid).
Maskelynitization
Shock event that converts plagioclase into isotropic glass phase called maskelynite.
Mesostasis
Fine-grained mineral mass found interstitial to major minerals.
Mineralogical mode
The mineral percentages, usually expressed as volume percent.
"mineral" separate
An attempt to obtain a concentration of one mineral phase after powdering the rock and using various mechanical means (e.g. heavy liquids for density difference).
Nakhlites
Clinopyroxenites like Nakhla, Lafayette, Governador Valadares, NWA 817, Y000593.
NHM
The Natural History Museum, London.
NIPR
National Institute Polar Research, Japan
NWA
North West Africa. Meteorites usually purchased from nomads in Morocco, but probably found in Algeria or even further east in Sahara.
NZ
Normal, basaltic lithology of Zagami.
Olivine-phyric
Texture of mafic or ultramafic rock where large olivine phenocrysts occur in a finer-grained matrix or groundmass; also a class of the shergottite meteorites.
Ophitic
Texture of basaltic rock where pyroxene completely encloses plagioclase and other phases.
"orangette"
New term used to distinguish unusual carbonate globules in ALH84001. However, term never caught on.
PAHs
Polycyclic aromatic hydrocarbons. Organic compounds made up of benzene rings linked together.
Pathfinder
Highly successful mission to Martian surface in 1990s.
Pre-terrestrial
The history of the sample before entry into the Earth's atmosphere – as judged by location with respect to fusion crust.
Plateau age
The age obtained from the 39Ar/40Ar spectrum as function of release temperature.
"pockets" of glass
The small areas of glass found inside the meteorite specimen.
"pods" of glass
The small unusual glass areas in EETA79001. See figure IX–24.
Poikilitic
Texture of igneous rock where small granular crystals are irregularly scattered without common orientation in a larger crystal of another mineral; also a class of the shergottite meteorites.
ppm
parts per million or micrograms per gram (unit of concentration) (1 in 1,000,000).
ppb
parts per billion or nanograms per gram (1 in 1,000,000,000).
Radiogenic Isotopes
Naturally-occurring, radioactive isotopes such as K, Rb, U, Th, Sm that decay at a slow rate to another stable isotope and are used for geological age dating.
REE
Rare earth elements (actually not so rare, generally diagnostic).
RNAA
Radiochemical neutron activation analysis (generally superior to INAA, because of use of internal standard).
"rosette"
A symmetrical growth form, resembling a rose, assumed by an accretionary body. Term often used for barite concretions on Earth.
SaU
Sayh al Uhaymir, Oman.
"salts"
Various non-silicate minerals, possibly residual to aqueous solution, found in cracks of Martian meteorites.
SEM
Scanning electron microscope
Schlieren
Texture where glass, or mineral phases are drawn out in stringers.
SIMS
Secondary Ion Mass Spectroscopy.
SNC
Shergotty, Nakhla, Chassigny, a term used in publications before "Martian meteorites."
Smithsonian Institution
see USNM below
SPB
Shergottite Parent Body = Mars
ST (replaced by KT,
and then replaced now by XI2)
The mail code for the "Office of the Curator" at JSC.


Shergottites

Meteorite type that includes several different kinds of rocks – a) those traditionally referred to as basaltic but now subdivided into diabasic, fine-grained, and gabbroic; b) those traditionally referred to as lherzolitic and now poikilitic, and c) olivine-phyric.
TEM
Transmitted electron microscope.
Terrestrial age
Time interval that meteorite has spent on Earth (for example, can sometimes be determined by analysis of carbon 14).
USNM
United States National Museum, also called the Smithsonian Institution. Washington D.C. Specifically, the Department of Mineral Sciences is a great source of research samples.
Viking
Two highly-successful missions to the surface of Mars in 1976.
"whole-rock"

Term used for a small sample (50 mg–2 g) of a rock used to determine the chemical composition of the "whole" specimen. Generally selected to be representative of the "whole", but, obviously, NOT the whole rock.
XRF
X-ray flouresence
"Yowza-Yowza"
Term used by 1984 ANSMET team to describe something important. New geological term, not found in Dictionary.