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Greenwell Springs meteorite, Baton Rouge, East Baton Rouge Parish, Louisiana, USA

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Latitude & Longitude (WGS84): 30° 30' 55'' North , 91° 0' 43'' West
Latitude & Longitude (decimal): 30.5152777778, -91.0122222222
Erratic type:Meteorite


Ordinary chondrite, genomict breccia (LL4,br; S3)
Found, November 1987; 664 g, single stone

A small blocky stone (~7x8x9 cm) was found on a recently cut lawn next to a 6 cm deep hole. Covered with a black glassy fusion crust, the interior contains abundant, devitrified chondrules up to 6mm in diameter comprising ~30 vol% of the stone. The light grey matrix is characterized by abundant small angular olivine- and pyroxene-rich clasts which range from nearly white to grayish black in color. The largely equilibrated olivine (Fa28.6) and mildly unequilibrated low Ca-pyroxene (Fs23.8,ave) are characteristic of LL4 chondrites. Mineralogically the meteorite consists primarily of dominant olivine [vol%] accompanied by sometimes twinned Ca-poor pyroxene along with minor plagioclase, diopsidic clinopyroxene, troilite, and Fe-Ni metal. Fe-Ni metal includes kamacite and 'cloudy' [zoned] taenite bordered by tetrataenite. Accessory chromite, ilmenite, and phosphates (both chlorapatite and merrillite) are also present.

The LL meteorites are ordinary chondrites that are relatively very low in total iron. They represent nearly 10% of all fully classified meteorite falls and a slightly larger proportion of total meteorite recoveries. LL4's account for ~10% of all LL-group chondrites. Greenwell Springs is one of 320 meteorites currently classified exactly as LL4 ordinary chondrite (May 2017). Despite Greenwell Springs's very modest mass it is still more massive than 85% of the listed LL4 chondrites. This is apparently due two two factors: (1) LL chondrites are often quite friable and prone to both disruption and destruction during atmospheric entry and (2) there are undoubtedly a number of disrupted fragments among the small Antarctic and Saharan meteorites which cannot be properly paired with each other.

Mineral List


9 valid minerals.

The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Graham, A.L., Editor (1988). The Meteoritical Bulletin, No. 66. Meteoritics: 23(2): 171-173. (June, 1988).

Byerly, G.R., Jarosewich, E., Mason, B. & Clarke Jr., R.S. (1988) The Greenwell Springs LL4 chondrite - A new fall from Louisiana, USA: Meteoritics 23: 359-360. (December, 1988).

Grady, M.M. (2000). Catalogue of Meteorites (5/e). Cambridge University Press: Cambridge; New York; Oakleigh; Madrid; Cape Town, 689 pages.

Kessel, Ronit (2002). The activity of chromite in multicomponent spinels: An experimental study with implications for the metamorphic history of equilibrated ordinary chondrites (Thesis). California Institute of Technology: Pasadena, California. 219 pages.

Kessel, Ronit, Beckett, J.R. & Stolper, E.M. (2007) The thermal history of equilibrated ordinary chondrites and the relationship between textural maturity and temperature: Geochimica et Cosmochimica Acta: 71(7): 1855-1881. (April 2007).

Dunn, T.L., Cressy, G., McSween Jr, H.Y. & McCoy, T.J. (2010) Analysis of ordinary chondrites using powder X-ray diffraction: 1. Modal mineral abundances. Meteoritics & Planetary Science: 45(1): 123-134. (January, 2010).

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