L chondrite

Their name comes from their relatively low iron abundance (less than 10%) with respect to the H chondrites, which are about 20–25% iron by weight.

Historically, the L chondrites have been named hypersthene chondrites or olivine hypersthene chondrites for the dominant minerals, but these terms are now obsolete.

Characteristic is the fayalite content (Fa) in olivine of 21 to 25 mol%. About 4–10% iron–nickel is found as a free metal, making these meteorites magnetic, but not as strongly as the H chondrites.{{citation needed|date=December 2012}}

The most abundant minerals are olivine and hypersthene (an orthopyroxene), as well as iron–nickel and troilite. Chromite, sodium-rich feldspar and calcium phosphates occur in minor amounts. Petrologic type 6 dominates, with over 60% of the L chondrites falling into this class. This indicates that the parent body was sizeable enough (greater than {{convert|100|km}} in diameter) to experience strong heating.D. Nesvorný et al. The Flora Family: A Case of the Dynamically Dispersed Collisional Swarm?, Icarus, Vol. 157, p. 155 (2002).

Many of the L chondrite meteors may have their origin in the Ordovician meteor event, radioisotope dated with uranium-lead method at around {{val|467.50|0.28}} million years ago. Compared to other chondrites, a large proportion of the L chondrites have been heavily shocked, which is taken to imply that the parent body was catastrophically disrupted by a large impact. This impact has been dated via cosmic ray exposure at around {{val|468.0|0.3}} million years ago.{{Cite journal|last1=Lindskog|first1=A. |last2=Costa|first2=M. M. |last3=Rasmussen|first3=C.M.Ø. |last4=Connelly|first4=J. N. |last5=Eriksson|first5=M. E. |date=2017-01-24|title=Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification|journal=Nature Communications|language=En|volume=8|pages=14066 |doi=10.1038/ncomms14066| pmid=28117834|pmc=5286199 |bibcode=2017NatCo...814066L |issn=2041-1723 |quote=A zircon U–Pb date of 467.50±0.28 Ma from a distinct bed within the meteorite-bearing interval of southern Sweden that, combined with published cosmic-ray exposure ages of co-occurring meteoritic material, provides a precise age for the L chondrite breakup at {{val|468.0|0.3|u=Ma}}}}{{cite journal|display-authors=etal |last1=Schmitz |first1=Birger |date=2019-09-18 |title=An extraterrestrial trigger for the mid-Ordovician ice age: Dust from the break-up of the L-chondrite parent body |journal=Science Advances|volume=5 |issue=9 |pages= eaax4184|doi=10.1126/sciadv.aax4184 |pmid=31555741 |pmc=6750910 |bibcode=2019SciA....5.4184S }} Earlier argon dating placed the event at around {{val|470|6}} million years ago. H. Haack et al. Meteorite, asteroidal, and theoretical constraints on the 500-Ma disruption of the L chondrite parent body, Icarus, Vol. 119, p. 182 (1996).Korochantseva et al. [http://www.ingentaconnect.com/content/arizona/maps/2007/00000042/00000001/art00009 "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40Ar-39Ar dating"] Meteoritics & Planetary Science 42, 1, pp. 3–150, Jan. 2007.

The parent body/bodies for this group are not known, but plausible suggestions include 433 Eros and 8 Flora, or the Flora family as a whole.

433 Eros has been found to have a similar spectrum, while several pieces of circumstantial evidence for the Flora family exist: (1) the Flora family is thought to have formed about 1,000 to 500 million years ago; (2) the Flora family lies in a region of the asteroid belt that contributes strongly to the meteorite flux at Earth; (3) the Flora family consists of S-type asteroids, whose composition is similar to that of chondrite meteorites; and (4) the Flora family parent body was over {{convert|100|km}} in diameter.{{citation needed|date=December 2012}}

The Massalia family is also a possible source of these meteorites.{{cite journal |last1=Marsset |first1=M. |last2=Vernazza |first2=P. |last3=Brož |first3=M. |last4=Thomas |first4=C. A. |last5=DeMeo |first5=F. E. |last6=Burt |first6=B. |last7=Binzel |first7=R. P. |last8=Reddy |first8=V. |last9=McGraw |first9=A. |last10=Avdellidou |first10=C. |last11=Carry |first11=B. |last12=Slivan |first12=S. |last13=Polishook |first13=D. |title=The Massalia asteroid family as the origin of ordinary L chondrites |journal=Nature |date=17 October 2024 |volume=634 |issue=8034 |pages=561–565 |doi=10.1038/s41586-024-08007-6|pmid=39415067 |arxiv=2403.08548 }}

• Glossary of meteoritics

{{Reflist}}

• [http://internt.nhm.ac.uk/jdsml/research-curation/projects/metcat/metsPerGroup.dsml The Catalogue of Meteorites] {{Webarchive|url=https://web.archive.org/web/20060503223656/http://internt.nhm.ac.uk/jdsml/research-curation/projects/metcat/metsPerGroup.dsml |date=2006-05-03 }}

{{Meteorites}}

fi:L-kondriitti