Orbits determined from observed meteorite falls indicate that most meteorites originate from the asteroid belt. Several additional orbits have been determined since this diagram was drawn, all of which support this origin.
Textural Types of MeteoritesStony meteoritesChondrites contain chondrulesAchondrites textures of igneous rocksIron meteoritesHexahedrites (H) consist of kamacite without taenite. Low Ni-content.Octahedrites (O) consist of kamacite lamellae with remnant taenite . Ataxites (D) consist of taenite only. High Ni-content.Stony-iron meteoritesMesosiderites mixed silicates and iron Pallasites olivines in a kamacite matrix
ChondritesChondrites are believed to have formed in the condensation of the solar nebula. Hence, they were never molten, but have been subjected to various intensities of recrystallization, characterized by grades from 1 to 6.Enstatite chondrites (E)EH are grades 3 and 4.EL are grades 5 and 6.H and L refer to high and low iron. EH and EL are generally believed to have separate origins.
Abee (EH4)Fell June 9, 1953,at Abee, Alberta
Ordinary ChondritesH Olivine-Bronzite
L Olivine-Hypersthene
LL Amphoterites (Olivine-Pigeonite)
Bruderheim (L6)Fell on March 4, 1960,at Bruderheim,Alberta
Chondrule from Riverton [Manitoba],an H5 ordinary chondrite
Carbonaceous chondrites (C) These represent some of the most primitive matter in the solar system. The Canadian meteorite, Tagish Lake, which fell in January, 2000, is a C2, probably the most primitive material ever recovered. The C-chondrites are subdivided according to chemical and petrographic characteristics into CI, CM, CH, CO, CV and CV. CI chondrites do actually contain chondrules but on the basis of their chemistry are considered to be C-chondrites. The C-chondrites have grades 1, 2 and 3, but grades 1 and 2 reflect degrees of aqueous alteration and grade 3 is essentially unaltered.
AchondritesAubritesDiogenitesUreilitesAngritesLoranditesHowarditesEucritesSNC meteorites Martian meteoritesShergottyitesNakhlitesChassignites
Stannern (Eucrite)Fell at Stannern, Bohemia (now Czech Republic) in 1908.
SNC (Martian) MeteoritesALH84001 (Allan Hills, Antarctica). This is the famous (or infamous) carrier of purported fossil life on Mars. Not actually an SNC type.
Detail of Allende, showing CAI inclusion(calcium-aluminum inclusion), believed torepresent condensation from the solar nebula.
Stony IronsGiroux (Pallasite) found at Giroux, Manitoba
Detail of Springwater Pallasite, found near Springwater, Saskatchewan.
Esterville (Mesosiderite)Found at Esterville, Iowa
The kamacite bandwidth is directly related to the Ni-content. As well, the principal trace and minor elements Ni, Ge, Ga and Ir lead to a chemical classification of iron meteorites. In addition As, Co, Cu, P, Pt, Re, Sb, and W have taxonomic value. These factors yield 13 chemical groups:
All of the iron meteorites were originally molten; i.e. magmatic in the true sense. However, they are classed as magmatic and non-magmatic on another basis.
Non-magmatic groups do not display magmatic trace element fractionation trends.IABIIICDThese two groups are now considered to be one calledIAB Complex.
Magmatic groups display magmatic fractionation trendsICIIABIICIIDIIEIIFIIIABIIIEIIIFIVAIVB
Henbury (Om group IIIAB)This polished and etched slice displays the Widmanstaetten pattern, characteristic of octahedrites.
