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| H chondrite | |
|---|---|
| Name | H chondrite |
| Type | Ordinary chondrite |
| Class | H group |
| Composition | Iron–nickel metal, olivine, pyroxene, troilite |
| Parent | Likely S-type asteroid |
| Notable falls | Hoba, Ensisheim, Pultusk |
H chondrite
H chondrite is the most common group of ordinary chondrites, representing a major fraction of recovered meteorites and informing models of Solar System formation, early thermal evolution, and asteroid parent bodies. Studies of H chondrites integrate results from petrology, cosmochemistry, and remote sensing to link laboratory samples with asteroid observations, meteoritic collections, and sample-return missions.
H chondrite fall and find specimens dominate curated collections at institutions such as the Smithsonian Institution, the Natural History Museum, London, and the Field Museum of Natural History. Research programs at organizations including the NASA Jet Propulsion Laboratory and the European Space Agency use H chondrite data alongside results from missions like Hayabusa, OSIRIS-REx, and NEAR Shoemaker to calibrate asteroid taxonomy schemes such as the Tholen classification and the SMASS classification. Major analytical facilities involved include the Argonne National Laboratory, the Massachusetts Institute of Technology, and the Max Planck Institute for Chemistry.
Mineralogy of H chondrites features abundant olivine and orthopyroxene together with kamacite and taenite metal phases, troilite, and accessory phosphates such as merrillite; these phases are routinely characterized by techniques developed at the California Institute of Technology and the University of Chicago. Isotopic systems studied at laboratories like the Geological Survey of Japan and the US Geological Survey include oxygen, iron, and nitrogen isotopes that tie H chondrites to particular isotopic reservoirs recognized in the Anglo-Australian Observatory and the Gran Telescopio Canarias datasets. Trace element and siderophile distributions measured using instruments from the Lawrence Livermore National Laboratory and the University of Tokyo constrain core formation and metal-silicate partitioning analogous to processes modeled in studies from the California Institute of Technology.
The H group is subdivided into petrologic types (3–6) defined by metamorphic grade; type 3 preserves the most unequilibrated textures studied at the Carnegie Institution for Science, while types 4–6 record progressive thermal metamorphism comparable to experiments at the Massachusetts Institute of Technology. The established classification schemes are maintained by curators at the Natural History Museum, London and the Smithsonian Institution, and their taxonomy is referenced in databases curated by the International Astronomical Union and the Meteoritical Society.
Dynamical and spectral evidence links H chondrites to S-type asteroids, with candidate parent bodies including prominent main-belt asteroids analyzed by the European Southern Observatory and the Keck Observatory. Thermal and collisional models developed at the Max Planck Institute for Solar System Research and the Institut de Physique du Globe de Paris support origin scenarios involving an asteroid with partial differentiation and an undifferentiated regolith, consistent with interpretations from the Dawn (spacecraft) mission and telescopic surveys by the Pan-STARRS project. Isotopic affinities compared with basaltic achondrites and iron meteorites have been discussed in papers affiliated with the University of California, Berkeley and the Southwest Research Institute.
Shock features in H chondrites—planar deformation features, melt veins, and opaque shock-darkened matrices—are examined using facilities at the Swiss Federal Institute of Technology in Zurich and the University of Münster. Thermal metamorphism histories reconstructed from closure temperatures of isotopic systems reference modeling approaches developed at the University of Arizona and the University of Hawaiʻi at Mānoa. Shock classification conventions used by researchers at the Meteoritical Bulletin and the Smithsonian Institution connect laboratory observations to collisional histories inferred from main-belt dynamics studied at the Instituto de Astrofísica de Canarias.
Historic falls and notable finds associated with H-type compositions include specimens cataloged from events such as the Ensisheim meteorite and the Pultusk meteorite fall, with large masses like the Hoba meteorite informing discussions of mass, ablation, and terrestrial weathering documented by the Natural History Museum, London and collectors reported in archives held by the Royal Society. Recovery campaigns and curation efforts led by the Smithsonian Institution and the Yale Peabody Museum of Natural History maintain provenance records important for cosmochemical interpretation.
H chondrites are pivotal for constraining models of early Solar System accretion, radionuclide heating (including effects of 26Al decay studies undertaken at the California Institute of Technology), and collisional evolution of the asteroid belt analyzed by the Southwest Research Institute and the NASA Johnson Space Center. Their widespread occurrence and well-preserved mineralogy make H chondrites reference materials in comparative planetology work at the University of Cambridge, the University of Oxford, and the Massachusetts Institute of Technology, and they continue to inform mission planning for asteroid rendezvous and sample-return projects coordinated by NASA and the European Space Agency.
Category:Meteorites