# L chondrite - Page: https://taslar.bumba.tr/en/stones/l-chondrite/ - Turkish: L kondrit - Also known as: Hypersthene chondrite (obsolete), Olivine hypersthene chondrite (obsolete) - Kind: Meteorite - Classification: Meteorites and impact stones › Stony meteorites - Hardness (Mohs): 5–7 - Specific gravity: 3.19–3.51 g/cm³ - Lustre: Dull - Transparency: Opaque - Colours: black (fusion crust), light grey (interior), dark shock veins - Composition: Mainly olivine (21–25 mol% fayalite) and hypersthene (an orthopyroxene), with 4–10% free iron–nickel metal and troilite, plus minor chromite, sodium-rich feldspar and calcium phosphates. - Texture: A stony meteorite with chondrules; over 60% are petrologic type 6, so strong heating has largely blurred the chondrules. A much larger share than in other chondrites shows heavy shock. - Value ladder: 5/9 step, Ornamental stone The second commonest meteorite group: low-iron ordinary chondrites, many heavily shocked, from an asteroid shattered 467 million years ago. L chondrites are the second most common meteorite group, making up about 35% of catalogued meteorites and 40% of ordinary chondrites. The “L” stands for “low”, as they hold less iron than H chondrites. Most show strong heating and heavy shock, suggesting their parent asteroid was broken up by a large collision. That break-up, about 468 million years ago, is thought to have temporarily raised the number of meteorites falling on Earth during the Ordovician. ## How does it form? L chondrites come from an asteroid that formed at the start of the Solar System from dust and chondrules but never fully melted. Over 60% are petrologic type 6, showing that the parent body was large enough, more than 100 kilometres across, to be strongly heated. A much larger share of L chondrites than of other chondrites shows heavy shock, suggesting that the parent body was completely shattered by a large collision. Cosmic-ray data date this break-up to about 468 million years ago. Which asteroid was the parent is unknown; 433 Eros, 8 Flora or the Flora family, and the Massalia family have been suggested. ## What is it used for? - **Earth history:** L chondrites help study the Ordovician meteor event and its possible effects on life at the time. - **Asteroid collisions:** Their shock features record the history of large collisions in the asteroid belt. - **Tracking meteorites:** Camera-tracked falls such as Novato help calculate meteorites' orbits before they reached Earth. ## Famous L chondrites L'Aigle (L6, 1803, France) is the fall that gave birth to meteorite science. Novato (L6, 2012, California) is a fall tracked by cameras and then recovered. The fossil L chondrites found in Ordovician limestone in Sweden are evidence of a meteor shower in Earth's past. ## How to recognise it - A black fusion crust outside; inside light grey, often with dark shock veins. - With 4–10% free metal it attracts a magnet, but not as strongly as H chondrites. - Since most are type 6, the chondrules show only faintly on a cut face. ## What determines its value? Being so common, L chondrites are relatively easy to find among meteorites. A piece's value depends on its mass, the freshness of its fusion crust, how rusted it is, interior features such as shock veins, and whether it belongs to a famous observed fall. This information is educational, not buying, selling or investment advice. Value varies enormously with quality and treatment. ## Myths and misconceptions - Myth: The number of meteorites falling on Earth has always been the same. Fact: In the Ordovician, about 467 million years ago, the break-up of the L chondrite parent body clearly raised the number of L chondrites falling on Earth, for about 40 million years. The evidence is fossil meteorites in Sweden and chondritic chromite grains in sedimentary rocks of that age. ## Curious questions **What was the Ordovician meteor event?** In the Middle Ordovician, about 467.5 million years ago, the number of L chondrites falling on Earth rose sharply, and the increase lasted about 40 million years. It is thought to have been caused by the break-up of the roughly 150-kilometre L chondrite parent body in the asteroid belt, which scattered fragments onto Earth-crossing paths. Shock ages in many L chondrites falling today support this date. ## Did you know? - They used to be called “hypersthene chondrites” or “olivine hypersthene chondrites” after their dominant minerals. - Abundant fossil L chondrites have been found in about 467-million-year-old limestone in a quarry in Sweden. - Cameras worked out the track of the Novato meteorite, which fell in California in 2012; after reading a newspaper story, Lisa Webber went looking for the source of a sound she had heard on her roof that night and found the first piece. ## Where is it found? - L'Aigle, Normandy, France (Historic source): A shower of more than 3,000 fragments of an L6 chondrite on 26 April 1803; Biot's investigation proved that meteorites come from space. - Novato, California, USA (Known locality): An L6 breccia that fell on 17 October 2012; thanks to the camera-based trajectory, the first piece was found by Lisa Webber, who had heard a sound on her roof that night. - Thorsberg quarry, Österplana, Kinnekulle, Sweden (Known locality): A quarry known for fossil meteorites in Ordovician limestone. Abundant fossil L chondrites from a quarry in Sweden show that L chondrite falls rose sharply about 467 million years ago. ## Sources - [L chondrite](https://en.wikipedia.org/wiki/L_chondrite), Wikipedia - [Ordovician meteor event](https://en.wikipedia.org/wiki/Ordovician_meteor_event), Wikipedia - [Österplana 065](https://en.wikipedia.org/wiki/%C3%96sterplana_065), Wikipedia - [L'Aigle (meteorite)](https://en.wikipedia.org/wiki/L%27Aigle_(meteorite)), Wikipedia - [Novato meteorite](https://en.wikipedia.org/wiki/Novato_meteorite), Wikipedia - [Meteorite porosities and densities: a review of trends in the data (D. T. Britt & G. J. Consolmagno), Lunar and Planetary Science XXXV, abstract 2108](https://www.lpi.usra.edu/meetings/lpsc2004/pdf/2108.pdf), Lunar and Planetary Institute, 2004 - [Handbook of Mineralogy: Enstatite](https://www.handbookofmineralogy.org/pdfs/enstatite.pdf), Mineralogical Society of America Source: https://taslar.bumba.tr/en/stones/l-chondrite/ · Licence: CC BY-SA 4.0