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Glossary

achondrite
a meteorite produced by secondary processes on large asteroids that have differentiated
adcumulate rock
a rock with a framework of touching crystals that continued to grow from the magma to the extend that less than 5 % of the rock consists of other minerals crystallized from the intercrystalline liquid
agglomerate
a fragmental rock dominated by rounded clasts larger than 64 mm in diameter or length
allotriomorphic rock
a rock with texture characterized by approximately equant anhedral grains
amygdaloidal rock
rock containing mineral-filled elliptically shaped vesicles
aphanitic rock
a rock with grains too small to see or identify with either the unaided eye or a low power lens
aplite
a very light colored, medium to fine grained, allotriomorphic-granular, quartz-alkali feldspar
barred olivine chondrule (BO chondrule)
chondrule with one or more sets of strongly elongated parallel prismatic olivine crystals
breccia
broken fragments of rock (clasts) cemented together by a fine grain matrix
Cape York
meteorite made famous by arctic explorer Robert Peary
chondrite
primitive undifferentiated stony meteorite formed as conglomerates containing chondrules, lack of secondary heating
chondrite matrix
fine grained disequilibrium mixture of low temperature materials from the Sun's protoplanetary nebula
chondrule
small sphere of about 1 mm diameter found in meteorites chondrule is composed of formerly melted or partially melted minerals
coarse-grained
common minor iron meteorite mineral
a common minor mineral found in the iron phase of iron and stony iron meteorites
compound chondrule
two or more chondrules conjoined during chondrule formation
cryptocrystaline chondrule (C chondrule)
chondrule with extremely fine-grained intergrowths of pyroxene and glass with grain size less than 2 micrometers
cryptocrystalline rock
ferromagnesian chondrule
chondrule with a high abundance of olivine and pyroxene crystals
fine-grained rock
fractional crystallized rock
a rock produced by differentiation in which part of the magma is crystallized and separated from further reaction with remaining liquid
granular olivine-pyroxene chondrule
chondrule with uniformly smaller grains than porphyritic chondrules
hyperleucocratic rock
very light colored rock with color index of 10 or less
hypermelanocratic rock
very dark colored rock with color index greater than 90
igneous rock
rock formed from the solidification of magma
inosilicate
SiO4 tetrahedra in single or double chains
iron meteorite
iron rich meteorites, often grouped chemically by similar ratios of trace elements to nickel
iron meteorite mineral
mineral found to occur in the iron phase of iron and stony iron meteorites
lava
leucocratic rock
light-colored rock with color index between 11 and 50
medium-grained rock
melanocratic rock
dark-colored rock with color index between 50 and 89
metal-rich meteorite
meteorite with metal content higher than that of average solar system material
metamorphic mineral
a mineral which can be metamorphic in origin but not necessarily
metamorphic rock
a rock which has undergone chemical and or structural transformation from its original solid form
metastable mineral
a polymorphic mineral in a high energy state relative to room temperature and pressure
meteorite
what remains after a meteoroid strikes the surface of a planet, satellite or asteroid
meteorite fall
a meteorite whose fall was witnessed by human or electronic means
meteorite find
a meteorite whose fall was not witnessed
meteorite fusion crust
melted glassy exterior of meteorite that forms by ablation during meteor phase
meteorite mineral
mineral found to occur in meteorites
microcrystaline rock
mineral not present on Earth
a mineral not known as a terrestrial mineral or extremely rare on Earth
mineral with rare element as major component
a mineral containing a rare element as a major component
nesosilicate
isolated single SiO4 tetrahedra
oriented meteorite
conical meteorite shape resulting from preferential ablation during atmospheric passage
peridot
gem quality olivine
phaneretic rock
a rock whose grains can be discerned without the aid of a microscope
piezoglypt
pit on meteorite surface
plutonic rock
cooling of magma in the interior of a planet or asteroid
polymict ureilite
fragmental breccias containing lithic clasts of typical monomict ureilite material plus a variety of other lithic clasts
porphyritic olivine chondrule (PO chondrule)
chondrule with porphyritic olivine crytals
porphyritic olivine-pyroxene chondrule (POP chondrule)
chondrule with a porphyritic mixture of olivine and pyroxene
porphyritic pyroxene chondrule (PP chondrule)
chondrule with porphyritic pyroxene crytals
presolar mineral
mineral predating the formation of the solar system found in meteorites
primary fusion crust
thin layer of ablated material that forms before a potential meteoroid break up from the beginning of incandescent flight until dark flight
radial pyroxene chondrule (RP chondrule)
chondrule with thin needles of pyroxene radiating from a single point on the edge of the chondrule
rare iron meteorite mineral
a mineral rarely found in the iron phase of iron and stony iron meteorites
regmaglypt
pit on meteorite surface produced by differential ablation of lower melting point mineral inclusion during meteor phase
rock
a solid mixture of one or more minerals
secondary fusion crust
forms on a freshly broken face if the meteoroid break up occurs before reaching the retardation point
stable mineral
a polymorphic mineral with the lowest possible energy state relative to room temperature and pressure
structural iron meteorite
a iron meteorite containing visible crystals of iron-nickel alloy
tectosilicate
SiO4 tetrahedra connected together at each apex in a three dimensional framework
terrestrially weathered meteorite mineral
mineral formed by terrestrial weathering of primary meteoritic mineral on Earth or during atmospheric entry
troilite
iron sufide common to many types of meteorites and in lunar rocks
type A chondrule
a chondrule textural classification based on the predominance of olivine crystals
type B chondrule
a chondrule textural classification based on the predominance of pyroxene crystals
type I chondrule
a chondrule compositional classification based on low iron oxide content and reduced oxidation state
type II chondrule
a chondrule compositional classification based on high iron oxide content and highly oxidized state
ubiquitous iron meteorite mineral
a mineral always present in the iron phase of iron and stony iron meteorites
undifferentiated meteorite
a primitive meteorite which has not been differentiated within a large asteroid
very coarse-grained (pegmatitic rock)
very common iron meteorite mineral
a very common mineral found in the iron phase of iron and stony iron meteorites
very rare iron meteorite mineral
a mineral very rarely found in the iron phase of one or a few iron meteorites
Widmanstatten figure
intergrowth of kamacite plates bordered by taenite on octahedral faces of octahedrite meteorites (exsolution lamellae)